Valve & Injector Pump Timing on the TEF 20 Diesel Tractor

To carry out this procedure front axle, diesel tank, injectors, rocker cover, front pulley, timing case and engine oil pump must have been removed.

Remove liming chain; new chain will be fitted during assembly.

All crankshaft settings in this article are made facing the engine from the front of the tractor.

Turn crankshaft until key is about 5 o’clock, turn camshaft to correct position and set No.4 cylinder tappets to a slack 22 thou. (0.0022″). Now turn camshaft until No.4 cylinder valves are on the rock, i.e. exhaust closing inlet opening. When in correct position a 8 or 10 thou. feeler gauge should be the tappet setting with both tappets. Valves are now in correct position and camshaft should now not be moved. Turn camshaft until key is a six o’clock No.1 and No.4 cylinders are now at T.D.C. ( Top dead centre).

Fit camshaft sprocket to camshaft but do not try and secure it with studs. Fit timing chain over all sprockets, now turn camshaft sprocket within the chain until the master hole in the sprocket, (one hole in the sprocket is straight drilled, all the others are elongated) lines up with a stud hole in camshaft but do make sure slack chain is taken up between camshaft and crankshaft sprockets. This done fit a stud in master hole in camshaft.

Now check tappets on No.4 cylinder, if still correct fit all studs to camshaft and make tight. Valve timing is now done. Reset tappets to 0.012″.

Now for fuel pump timing. Fit chain tensioner sprocket. You will have to make a tool that will keep the tensioner adjusted to keep chain tensioned while doing pump timing. (This tool only replaces the tensioner in the timing cover).

With chain tensioned slowly turn crankshaft anti-clockwise until a thin screwdriver can locate the spill timing hole in flywheel. This is a hole in block above sump joint under union for oil pressure gauge pipe, having found this replace the screwdriver with a rod that just fits the hole, (approx.’ /4″ diameter). Now unscrew No.1 delivery valve holder from injector pump, then remove spring and delivery valve from pump and keep in a very clean place.

Refit valve holder to injector pump.

Attach some form of fuel tank. I always attach fuel feed from this tank to inlet on pump, but care must be taken that no dirt is allowed to enter the fuel system. The correct way is to let fuel go through filters and in the case of engines fitted with lift pump you will have to hand pump fuel to keep up pressure throughout the following operation.

You will now need another special tool so as the injector pump can be turned. This tool consists of a nut the same thread as the pump drive shaft, this nut should be welded onto a short (1 “) bolt with only 2 or 3 threads showing that will screw onto pump drive shaft. Drill the bolt end through the hexagon so a short tommy bar can be inserted through, this done timing can be started, the sprocket will already be fitted for valve timing. If not already dismantled, remove the two nuts from the pump drive.

Before removing the internally and externally serrated (splined) drive coupling from the shaft and sprocket, centre pop the coupling and sprocket boss, this may help in assembly. Now remove this coupling.

Place a container under engine to catch diesel and turn on diesel supply. If you go through the filters bleed fully to get rid of all the air. Now fit loosely onto pump drive shaft the splined coupling and screw onto shaft your special tool. You can see why this tool can only be screwed on 2 or 3 threads, as the coupling has to be loose between special tool and sprocket.

Turn the injector pump with a T bar through your special tool a few times. You will have fuel gushing out of the No.1 delivery valve holder, this will come in 2 different types of gushes, a short burst (spill) and a longer burst (spill). Now turn pump till the short spill has gone and the long spill starts. Keep turning until the long spill starts to slow down. keep turning the shaft very very slowly and blowing into No.1 delivery valve holder until fuel is only just to say creeping up the holder but not stopped. Now the fun starts. The splined coupling now has to be inserted into sprocket and over pump drive shaft. Start with the centre pop marks lined and then work round from there. Don’t force home this coupling, you will find a place where it will slide in. Keep checking that fuel is just creeping up delivery valve holder. When the coupling is correctly assembled remove special tool and fit 2 nuts.

Refit delivery valve and spring into delivery valve holder and, important, now remove rod from engine block and flywheel. Remove your chain tensioner tool and refit oil pump with gasket. Before fitting timing cover make sure the timing chain adjuster in chain case is very free and can be turned freely by hand. Screw this out to end of thread then fit cover and bolt up (with new seal and gasket). Now screw in by hand the chain adjuster screw until tight, then turn a little further with a spanner. Refit front pulley and injectors, these will have been removed so you can freely turn engine.

Refit axle etc and start engine. rev engine up and down. If there is a distinct whine the timing chain is too tight. This noise will only be heard when you have shut throttle, (on the slow down) readjust timing chain until this whine has just gone. If there is no whine, chain may be too slack so it is advisable to tighten until a faint whine is heard and then slacken off.

This now completes the job, but a word of warning as with any diesel engine the valve timing has to be spot on or damage will be done to valve gear or at worst a piston. I stress if you are not sure, seek help from someone who can do it. If you get fuel pump timing wrong all that will happen is the engine will not run. Also there will be those of you that will say I should use a swan neck pipe for spill timing. As an apprentice I was taught spill timing in the way I have explained as it was more accurate than a pipe. I haven’t changed this method for 45 years.

Published in Journal No.41 Summer 2002, Malcolm Rainforth No. 3392

Recently two well known tractor magazines have stated that the only way to remove the pistons from a TEF20 is by removing the crankshaft and then pulling out the pistons down into the crankcase. That statement is incorrect and I would like to give the correct method to hopefully prevent members from taking this wrong advice.

Yes, if the crankshaft has to be removed then the pistons can be removed this way but to try and refit pistons by reversing the method is about impossible. Perhaps the assumption about removing the crank was made after failure to remove pistons and connecting rods in the normal way. These can, however, be removed if the correct method is used as I will explain.

All TEF engine blocks have a cut-out piece at the bottom of the cylinder and on the early engines the liner had a slot at its base that lines up with the slot in the block.

This then allows the connecting rod big­end to be pushed up far enough for the piston to slip out of the liner at the top after removal of 2 inserts, one of which is held in place by a peg. Great care must be taken not to drop this peg into the water jacket. By using a tool to hold the piston in place, see diagram, the piston can now be removed, the connecting rod will fall into the crankcase and the liner can then be removed. Rebuilding is done in reverse, once again made easier with the correct tooling

Now, and this is probably the engine the magazine experts tried to dismantle, on the later engines the liner didn’t have the slots (I don’t know for what reason) but the slots were still in the block and so to remove the pistons on this engine the liner has to be removed first, then the piston and connecting rod can be pushed out far enough to be removed in the same way as with the previous early type.

The rebuilding though, on this engine, is not quite as simple. It is done in reverse again with the liner being pushed down over the piston. A special ring clamp makes this task a lot easier as without it great care needs to be taken so that none of the rings are broken.

I am told that the only liners available now are the unslotted type. I haven’t rebuilt one of these engines for quite a while now but I shall be doing shortly as my next project is a total rebuild of a TEF however I have piston & sleeved dozens of both type and certainly didn’t remove the crankshaft to do it. I have written to the relevant magazines explaining that their articles were incorrect!

This is only a rough guide to removal and replacement of TEF pistons and sleeves and is a much bigger job than this article might suggest.

Published in Journal No.66 Winter 2010/11 :  Malcolm Rainforth

First published in Journal No.37 Spring 2001

Now let’s assume that our tractor (TEA) is using oil and blowing from the crankcase breather, indicating worn piston and cylinder liners. So we will deal with fitting new pistons and liners first. There are other methods or curing the above conditions (dealt with later) but first we will go for perfection.

1. Remover the cylinder head and fit washer tubes to prevent the liners moving (as described in past issues).
2. Drain oil from sump, also removed oil filter.
3. Whilst oil is draining turn engine until all pistons are halfway up the bores.
4. There will be a ring of carbon around the top of the bores, remove this with a scraper, then the pistons will corne out easier.
5. Remove nuts retaining the oval gauze filter mounted on the right hand side of the sump (manifold side) and draw out gauze filter.
6. Remove all sump bolts between sump and front axle mounting.
7. Remove sump, it may require a tap to break the seal.
8. Turn the engine until No.1 big end is at lowest position. Check No.1 is stamped on rod and cap (alongside bolt).
9. Knock back lock tabs, remove big end bolts, remove big end cap.
10. Using a piece of hard wood (hammer shaft) push or tap the piston and rod out of the cylinder. Replace big end cap.
11. Repeat on other three cylinders .

Removal of cylinder liners:

Universal Puller – non Ferguson Liner

Ferguson Puller – TE20 Liner

Before removing the liners, place cloth/rag over the crankshaft as it prevents dirt falling on the shaft.

A puller is required to remove the liners, some move easily whilst others can be very stubborn.

The puller (See Figure 1) consists of a thick steel disc, the same diameter as the liner spigot, and machined on the top edge to fit into the cylinder bore. The plate is drilled in the centre to take a threaded bar. The bar then passes through the disc, up the cylinder and through a bridge piece, over the liner and on the block face. A nut is then placed on the threaded bar and tightened up. By tightening the nut the liner will be pulled out of the block. Having removed on liner the procedure follows on the other three.

With all the liners removed it is a simple matter to clean the water space of all dirt and corrosion.

When the block and crankcase are clean it is vital that the figure 8 faces, where liner and block meet, are immaculately clean otherwise water will pass into the sump.

Refitting cylinder liners

Once again I would remind you that cleanliness is vital when assembling any parts and in particular mating faces and joints.

1. I find that the easiest way to fit the liners is two at a time.
2. Place two liners on the bench with the spigot uppermost, put a very small amount of water pump grease on the joint face (to hold to gasket).
3. Place figure 8 gasket over the spigots and on the joint face.
4. Carefully lift the two liners and slide into the block.
5. Repeat with the other two liners.
6. Fit liner retaining washers and tube pistons.

Having fitted new liners, our next step should be to fit new pistons, but firstly, we must remove the old ones from the rods.

Warning: never remove pistons by putting the rod in a vice and knocking out the gudgeon pin, it will probably distort the rod.

I always place a container of water on a stove and bring the water to the boil, then, having removed the circlips from the piston, place the piston and rod assembly in the water for a few minutes. Remove assembly, having as assistant to hold the piston with a rag (it will be very hot) and push, or tap out the gudgeon pin. Repeat on all pistons.

The new pistons usually come with rings and gudgeon pins assembled so we need to use the water system again to remove the pins. Always ensure that the pins stay with the correct piston.

Before we fit any new pistons, we need to check the little end bushes for wear.

To carry out this check we need the connecting rod and a new gudgeon pin, both at room temperature. The pin should be a sliding fit in the bush with NO lift or wobble.

If there is lift or wobble then bush(es) need to be replaced to give satisfactory results (no taps or rattles).

Replacing the bushes is done by pressing out the old and pressing in the new, then the new bush must be reamered out to the fit of the pin. This calls for great skill. As the reamered is being carried out it is imperative that the reamer is always parallel to the big end and also at 90 degrees to the rod. Therefore, I strongly recommend that any rebushing of the little ends is carried out be a professional motor engine machinists who will have the know how and jigs. Frequently replaced bushes finish off worse than the originals.

Fitting the new piston

Having checked the little ends and found them serviceable or had them rebushed, we can now fit the pistons to the rods. However, it is vital that they are fitted in the correct manner so we need to study the rod and piston. Studying the piston we see one side of the wall or skirt is plain (solid) and the opposite side is split. The plain side must go to the thrust side (carburettor) of the engine.

How to find the thrust side.

Figure 2.

Studying the rod we will see that the big end cap is cut at an angle, the rod portion of the big end goes to the thrust side (carburettor) and the cap to the right. (See Figure 2).

Knowing the correct way to assemble pistons and rods we can carry on. The gudgeon pins have been removed from the piston previously. Fit one circlip into the piston. Place piston into boiling water to expand it, leaving gudgeon pin on the bench ready for fitting.

Grip rod in vice, it will cause no damage as the pin is pushed in by hand (no knocking).

Lift piston from water (with hooked wire) grip with rag or gloved hand and place correct way round over rod, line up holes and push in gudgeon pin.

Fit second circlip. Repeat on other pistons.

Fitting piston/rod assembly to engine

Ring Compressor

The rods are numbered so fit No.1 rod to No.1 cylinder, etc. Check split in piston skirt and big end cap goes to camshaft side. (See Figure 2).

In order to fit the piston rings in the cylinders it is necessary to use a piston ring compressor. These vary in type, some are like a coned shape unit that compresses the rings as they pass through, others are like a hose clip that compress the rings as they are tightened. Whichever type you use try it first.

Take the piston to be fitted and smear it with oil. Turn the rings so that the gaps are staggered. Using the compressor push into the correct cylinder. It may be necessary to lightly tap the piston crown with a screwdriver handle or piece of wood to assist fitting but NEVER hammer – it breaks the rings. Repeat on the other pistons.

Fitting replacement rings

Fitting new piston rings often causes arguments amongst engineers, some maintaining that it is not sound practice to put a new (round) ring on a worn (oval) cylinder.

However over the past 50 years I have fitted hundreds of ring sets into worn cylinders with satisfactory results. The vital factors are, you must have the correct sized rings and they must be fitted correctly.

Before dealing with the fitting of the rings, a word or two regarding sizes may be useful. When new, Ferguson fitted a piston with five rings, three compression and two oil scraper and of course, a standard bore size of 80mm or 85mm. Over the years many of our engines have had replacement cylinders and pistons fitted. These may well have been genuine Ferguson parts ­therefore no problem, BUT, if for instance the local garage carried out the work, then probably they would obtain the parts via the trade contacts – hence possible problems.

In the 1950’s and 1960’s there were at least three major piston suppliers, all making pistons to a common size, BUT, some did vary the size of the ring width, hence the possible problem. Also in this era it was common practice for the cylinder to be rebored and oversized pistons fitted so we may find pistons 80mm plus .010 or .020 etc. All points to be aware of, hence my words of caution.

Therefore, before we start ordering parts we need to check the sizes required, first job – clean things up and check sizes.

Firstly, the simple task is to deal with the cylinders.

We have already scraped the carbon off the top of the cylinders, but there is likely to be a step (ridge) in the cylinders worn by the rings. This will be greater on one side than the other. I like to remove this by scraping it off with a bearing scraper. The reason for this is that when new rings and possibly new bearings are fitted, the piston and rings will travel a few 1000’s of an inch higher up the cylinder, if the step is there it could damage the ring, hence the removal.

Having removed the step there is one further job with the cylinders. Due to use, the cylinder walls will have become glazed (polished), this needs to be removed to enable oil to stick to the walls and so prevent further wear.

The trade way of removing this glaze is to run a glaze buster through the cylinders. This tool consists of three spring loaded stones which are placed in the cylinder and then spun round with a drill whilst being moved up and down the cylinder.

As many tractor owners will not have access to such a tool, we need to remove the glaze the simple but hard way, i.e., take about half a sheet of medium emery paper and work it up and down and also around the cylinders until the glaze has gone. Keeping the paper damp with paraffin will make the job easier and quicker.

The cylinders are now ready to accept the pistons, so, back to the pistons.

The first job with the pistons is to remove the old rings. Nip the rod in a vice with the piston on top of the jaws (this holds the piston firm). Turn the ring gap to face you, place a thumb each end of the gap and gently push outward and lift the ring off the piston. Repeat until all the rings are off.

Having removed the rings, take one compression and one oil scraper ring (if you break any when removing the broken bits are ideal) and grind or file a cutting edge on one end. (Ensure it has an edge like a wood chisel). These sharpened rings are now used to scrape ALL the carbon from the ring grooves, particularly the bottom of the groove.

Any carbon or dirt left in the groove will prevent the new ring from being fully compressed, therefore preventing it entering the cylinder.

Having cleaned the grooves, remove by wire brushing all the carbon and dirt from the rest of the piston.

Cleaning the ring grooves with a piece of broken piston ring.

When the crown (top) of the piston is finished, study it carefully as the size is usually stamped on, i.e., STD is standard, +.020 is .020 over size, etc.

With all the pistons cleaned and checked we can now obtain new rings. It is good practice to take a piston to the supplier and let them measure the size to avoid any mistakes. As mentioned before, size and width of rings can differ from standard.

Having obtained our new rings, the first job is to check that they are correct. If we are fortunate the rings will be packaged individually and each package will bear full fitting instructions. If this is the case the information is well worth reading. However, many are packed loose so we need to check as follows:

1. Have we enough rings for each groove on all pistons?
2. Separate oil scraper (the ones with slots in) from compression (plain).
3. Check compression rings, some may be tapered, in which case the word TOP will be stamped on one face of the ring. TOP of course, goes to the piston crown.
4. The top compression ring is usually a plain ring (all compressions may be plain, it depends upon make supplied).
5. Check ring gap. This is done by placing the ring in the cylinder and using the piston as a pusher. Push the ring about 1″ down the cylinder. Using feelergauges, check the gap. Ring gap 002″ per inch of bore, e.g., 80mm = .007″ approx. (See Figure 4).

Figure 4. Checking the ring gap.

Figure 5. Check that the ring fits into the groove correctly

6. Check depth of ring groove and ring depth by placing the end of the ring in the groove. (See Figure 5)

7. Check ring to groove width. This is done by fitting the ring to the piston and checking with feeler gauges (gap about .006″). (See Figure 6).

Figure 6. Checking the gap hetween the new ring and piston

8. These checks eliminate any problems later and are worth doing. If the gap is over .007″ it indicates a worn bore and is usually overlooked as the only other satisfactory answer is new pistons and liners. Depth of ring and groove, Figure 6, is usually correct unless there is carbon or dirt in the groove. Ring width, Figure 7, will increase if the old ring has worn the groove. A small increase, say .005″ is permissible, but greater amounts indicate a worn piston or wrong rings supplied (check with supplier).

9. Having carried out checks on all rings, we can now fit the rings to the pistons.
10. Grip con rod in vice with piston resting on jaws. Fit bottom scraper ring first by gently pushing out the gap with each thumb (as removal).
11. Fit next scraper ring.
12. Fit compression rings. Check if any are tapered, e.g., TOP to piston crown.
13. Top compression, usually plain. If cylinder bore was worn or stepped the new ring may fowl at the top of the stroke, so it is recommended to remove a small aruount of the top outside edgeof the ring. This can be carefully done with a smooth flat file or by using a very very fine grind stone, but take care. (See Figure 7).

Figure 7. The top ring wears a ridge in the cylinder wall.

14. With all rings fitted, smear piston with oil, stagger ring gaps, and using ring compressor, refit pistons as described earlier.
15. Refit big ends, bend over lock tabs,
16. Refit sump and gauze filter.
17. Refit oil filter and fill sump.
18. Refit cylinder head and adjust valves etc.
19. Start and test.

Remove the wear ridge

A new ring will hit the wear ridge.

The removal of the ridge at the top of the ring travel is often desirable before installing new rings in a worn cylinder. As wear takes place the top corner of the ring wears to fit the rounded shoulder formed at the top of the ring travel.

If a new square cornered ring is installed in the top groove, and the ridge is not removed, the corner of the new ring will strike the rounded lower surface of the ridge, and not only cause a tapping noise, but may bend or break the second land ­thus locking the second ring in its groove. This is still more important when new bearings have been fitted, which will lift the piston further up the bore.

When wear is appreciable, it sometimes becomes necessary to remove the ridge before the piston assembly is removed for examination, as it may be impossible to remove the pistons and rings through the top of the bore without bending or breaking the ring lands.

First published in Journal No.37 Spring 2001, and reproduced again in Journal No.105 Summer 2023

Most old Ferguson aud Massey Ferguson tractors require the timing cover seals changed because of old age and to stop engine oil leaking out causing a mess down the front of timing cover. The other problem you find is that the crankshaft drive pulley is all marked or grooved where the seal runs so if you just change the seal it will just wear the seal like the old one and start leaking? What you can do is fit a speedy sleeve that slips over the end of your crankshaft drive pulley and it gives you a perfect smooth face for seal to sit on. These speedy sleeves can be bought nom your local bearing companies or motor factors. All you need to do is measure the circumference of the craukshaft pulley shaft, then the width of the seal aud inside diameter of the seal, then they should be able to get the closest size of speedy sleeve to complete your job. Your tractor will run with oue less oil leak.

Published in Journal No. 82 Spring 2016 : Kevin Britton

In the last issue, Journal No.31, we studied the ignition system, so the next logical step is to service the fuel (petrol) system. However, firstly, Health and Safety:

The design of the Fergie fuel system lends itself to fire. Over the years, particularly when new, we had regular work with fire damaged units usually caused by: • Filling up whilst running • Overfilling and spilling on to the hot exhaust • Overfilling and spilling on to the ignition or starter

I also know of one case of a driver ending up in hospital through checking his tank contents, whilst smoking – result the tank exploded. So be warned, fuel systems are dangerous.

As Qur tractor has stood for quite a considerable period of time we need to completely clean and check the system. We need to start at the tail.

Firstly take a sheet of plastic and place it over the ignition and starter, pushing the top end behind the fuel tap and between the valve cover and tank. Any leakage will now be kept dear of the electrical systems.

1. Turn OFF fuel supply, TE-A – screw tap (-Wheel, Fig 1 D) in fully TE-D – ensure top handle is vertical.
2. Remove fuel pipe.
3. TE-A – using a spanner on square at top of casting, unscrew assembly from tank. It is ideal to have an assistant ready with a container to place under the tank- to catch whatever runs out. TED With this model you will need to remove two union screws (13 Fig 2).
4. Any stale or contaminated fuel has now been removed and gauze filter on the top of the bolt can be cleaned. With the TE-A, the gauze on top of the tap assembly requires cleaning. In addition the glass bowl and gauze filter (13 Fig 2) can be removed and cleaned. The assemblies can now be replaced in reverse order. The rubber washers (14 Fig 2) above the glass should be renewed. However, if a new one is not to hand, turn the washer over, this usually seals better.

1. TE-D – Refitting the tap assemblies and union screws does not usually cause any problems, and the assembly automatically lines up with the pipe. The TE-A, however, is slightly different, you are screwing the assembly into the tank, and also you need to stop in the correct position for the fuel pipe to screw into the assembly. It is therefore prudent to use a little PTFE tap on the threads as this will allow you to get a tight joint, but still allowing correct location to mate up with the fuel pipe.
2. Connect up fuel pipe.

At this stage, do not turn on any fuel, we need to service the carburettor first. However, a word about the tap operation.

TE-D – as stated above, the fuel is OFF when the tap is vertical. Turn the tap top to the rear is petrol ON. Turn the tap top forward is TVO ON.

TE-A – screwing the tap (wheel) out twice is MAIN supply ON. Screwing tap fully out is RESERVE supply ON. (See Fig I A and B).

CARBURETTOR

Moving, to the other side of the tractor, we can attach the Carburettor.

1. Remove the fuel pipe from the carburettor.
2. Remove the clevis pin from the front end of the throttle rod.
3. Remove air intake pipe from carburettor and air filter. It is better to remove the pipe completely as it makes it easier to get at the choke and the air fUter will need servicing.
4. Remove the choke control rod by taking out the split pin.
5. Remove the carburettor assembly by removing the two nuts and washers from the flange to manifold joints. The carburettor should now be taken to a clean well lit bench as many of the parts to be removed are small and are easily dropped or lost.
6. Firstly, wash, brush or blow off any external dirt. Then study the unit and note the layout of the parts. Please note that the throttle and choke levers are interlinked. I recommend that you mark the top of the tube (18 fig 3) as this can rotate when dismantled (more of this later).
7. Remove the five screws (3 fig 3) and separate the upper and lower units (7 and 25 fig 3).
8. Remove airjet 38, slow running tube 39, gasket 41, and float 40. NB the float fits top uppermost. Tube 24 may pull out easily, if not leave it in place, there is no need to remove this.
9. Unscrew float needle 42 and 43, this may well need replacing (more later).
10. Remove air screw and spring 45 and 44.
11. Moving to the lower unit, unscrew main jet needle 36 about two or three times (this ensures ease of assembly), then unscrew adaptor 33 and remove needle and adaptor assembly plus washer 36, 33, 32 Fig 3) Now using a good fitting screwdriver, remove main jet 31. The screwdriver needs to be a good fit in the jet slots, but must not damage the threads in body 25. The main jet washer 30 usually remains in the body, if so leave it there but be aware of it being blown out during cleaning. This is necessary so do not lose it.
12. Next, wash out the bowl assembly. I normally use clean fuel, but be careful, it is highly inflanunable. It is necessary to blowout many components as they are refit. A blow gun and compressed air supply is ideal, but if this is not available, other methods must be used. A bicycle pump with an adaptor for blowing plastic footballs works well, but an assistant working the pump makes life easier.
13. Blowout the bowl and all the holes in the lower body. Be sure to blow through the holes where items, 38, 39 and 31 come out of. Beware of the washer 30, it is in the housing.
14. Blow through main jet 31 and refit, ensure washer 30 is in place first and ensure jet is screwed up tight. Refit adaptor 33 complete with needle and washer 32 and tighten.

Now screw in needle 36 until just tight then unscrew TWO complete turns. This is standard setting (more later).

15. Place float 40 in bowl with the word TOP uppermost. Replace Tube 24 (if it was removed), replace gasket 41 if in good condition, or fit a new one.
16. Blow through air jet 38 and slow running tube 39 and refit (they will not fit in wrong holes).

17. Moving to the upper assembly, blow out the air screw hole (where screw 45 fits) and the hole in which the float needle 42 fits. Blow the hole in bolt direction, dirt regularly congregates here. I strongly recommend fitting a new float needle valve 42 and washed 43 as these items control the fuel at the correct level. I am aware that increasing the thickness, or number of washer can alter the fuel level, but with this type of valve we cannot view the needle or seat and it is likely to be many years old and therefore worn. Fitting a new unit should ensure trouble free rallying and give economical running.
18. Now refit air screw and spring 45 and 44 screw in air screw fully and unscrew ONE complete turn (standard setting – more later).
19. Now the upper and lower units can be reunited. Do not forget to place rod 11 in tube (18 fig 3) The tube needs to be refit with the mark (put on when dismantled) to the top. Screw in five screws (3 fig 3) and tighten. Close throttle butterfly (1 fig 3) and operate choke lever 26. This action should slightly lift throttle butterfly, via linkage (11 and 18 fig 3). If this does not happen the tube 18 could have been refit upside down, or it needs lifting by slackening screw 28 and raising the tube slightly. The choke opens the throttle slightly to assist starting.
20. Refit carburettor to manifold using a new gasket so as to ensure a gas tight joint.
21. Refit fuel pipe, throttle, rod clevis pin and air cleaner pipe. (Servicing aircleaner next issue).

START UP

Now we can check and adjust oil, water and fuel if necessary. Turn on fuel, ignition and start up, allow engine to warm up and then check adjustments. With the engine warm close throttle control, this should give an idler speed (tick over) of 400-450 rpm, or, 145 – 165 rpm (PTO Shaft). This is checked by a tachometer or by listening. To adjust idle speed, using screw (6 fig 3) clockwise to increase, anti clockwise to decrease.

AIR SCREW

One turn open (as set) is usually correct, but try a SUGHT adjustment in and out and see if a sweeter idle can be obtained. This adjustment can vary so much from engine to engine so it has to be – try and see but remember a minute movement of the screw CAN make a great difference.

MAIN JET

The main jet has been set two turn open (standard). This may be varied to suit the work the engine is required to do. A tractor quietly running on a rally field may require one and a half turns, whereas one pulling a load up a hill may require two and a half. Therefore, adjust to suit type of work.

Published in Journal No.31 Spring 1989 – Arnold Staples

How Does a Carburettor for a Tractor Engine Work?

This is a very basic general description, but we have to start somewhere!

You know that the idea behind an engine is to burn fuel to create pressure, and then to turn the pressure into motion. A remarkably tiny amount of fuel is needed during each combustion cycle. Something on the order of 10 milligrams of fuel per combustion stroke is all it takes!Carburettorsngine runs properly. If there is not enough fuel mixed with the air, the engine “runs lean” and either will not run or potentially damages the engine. If there is too much fuel mixed with the air, the engine “runs rich” and either will not run (it floods), runs very smoky, runs poorly (bogs down, stalls easily), or at the very least wastes fuel. The carb is in charge of getting the mixture just right.

Nearly all older vehicles, and all small equipment like lawn mowers and chain saws, use carbs because they are simple and inexpensive.

The carburettor on a tractor is a good example because it is so straightforward. The carb on a tractor is simpler than most carbs because it really has only three situations that it has to cover:

• It has to work when you are trying to start the engine cold.
• It has to work when the engine is idling.
• It has to work when the engine is wide open.

No one operating a tractor is really interested in any gradations between idle and full throttle, so incremental performance between these two extremes is not very important. In a car the many gradations are important, and this is why a car’s carb is a lot more complex.

You can see the carb for various tractors in the diagrams following.

Here are the parts of a carb:

• A carburettor is essentially a tube.
• There is an adjustable plate across the tube called the throttle plate that controls how much air can flow through the tube.
• At some point in the tube there is a narrowing, called the venturi, and in this narrowing a vacuum is created.

In this narrowing there is a hole, called a jet, that lets the vacuum draw in fuel.

The carb is operating “normally” at full throttle. In this case the throttle plate is parallel to the length of the tube, allowing maximum air to flow through the carbo The air flow creates a nice vacuum in the venturi and this vacuum draws in a metered amount of fuel through the jet.

When the engine is idling, the throttle plate is nearly closed. There is not really enough air flowing through the venturi to create a vacuum. However, on the back side of the throttle plate there is a lot of vacuum (because the throttle plate is restricting the airflow). If a tiny hole is drilled into the side of the carb’s tube just behind the throttle plate, fuel can be drawn into the tube by the throttle vacuum. This tiny hole is called the idle jet.

Both the jets have screws restricting the fuel flow, these are simply needle valves. By turning them you allow more or less fuel to flow past the needle. When you adjust them you are directly controlling how much fuel flows through the idle iet and the main jet.

When the engine is cold and you try to start it, the engine is running at an extremely low RPM. It is also cold, so it needs a very rich mixture to start. This is where the choke plate comes in. When activated, the choke plate completely covers the venturi . If the throttle is wide open and the venturi is covered, the engine’s vacuum draws a lot of fuel through the main jet anon is a vertical instrument in general use on light

Commercial Vehicles, Marine Engines, Stationary Industrial Plant and various types of Mobile Agricultural equipment. The float the idle jet (since the end of the carb’s tube is completely covered, all of the engine’s vacuum goes into pulling fuel through the iets). Usually this very rich mixture will allow the engine to fire once or twice, or to run very slowly. U you then open the choke plate the engine will start running normally.

Published in Journal No.41, Summer 2002, Alan Dunderdale

FERGUSON TRACTOR CARBURETTORS

In this article I have tried to cover most of the carbs as fitted to Ferguson tractors. This is NOT a technical article, but it is intended only as an informative general guide to carburettors.

I have included the combine harvester carb, 30VEA as some of these engines have been used as replacements for the Ferguson engines.

The Zenith 24T Carburettor as fitted to the Ferguson Range of Tractors (1947 • 1949)

The 24T-2 Carburettor shown in cross section is a vertical instrument in general use on light Commercial Vehicles, Marine Engines, Stationary Industrial Plant and various types of Mobile Agricultural equipment. The float chamber is offset in order to keep it as close as possible to the main discharge tube, thus ensuring high angle operation in any direction without flooding, or stalling. The instrument can be arranged to take all air through the main intake, which is invariably protected, by an air cleaner. This feature is called for when working under dusty conditions close to the ground, if long life and reliable service are to be obtained.

The carburettor consists of two main castings, the upper or barrel portion being secured to the lower bowl portion by five screws, one of which is shown (8).

In order to keep this carburettor as simple as possible we have used One principal jet and a slow running jet.

Suitable air bleeding is arranged to atomise the fuel and to maintain correct mixture strength under all conditions of engine operation. The above drawing shows the principal, or main jet (2) covered by the large hexagon plug (1). The slow running jet is also shown (15). The air bleeding to the main iet system is controlled by the air jet (14), and this air supply is taken from the main air intake. It will be noticed that this air issues from the holes (4), (5) and (6), at high engine speeds when the fuel In the main discharge tube (7) falls to its lowest level. Fuel metered by the slow running jet (15) is atomised by an air supply taken through the main air intake and controlled by the screw (12). This mixture issues through the idle discharge channel (10) and the progression orifice (11). The float chamber contains a normal type float (19) and the usual combined needle­ seating valve (18). The latter part is usually fitted with one washer, but two washers can be used if it is desired for any reason to lower the fuel level in the float chamber.

MAIN ADJUSTMENT

The combination of choke tube, main jet and air jet will be found correct for the engine to which the instrument is fitted and it should not be necessary to alter these parts. When dealing with ordinary running trouble. Cleanliness is the keynote for good results, Take special care to use a suitable screwdriver when removing the main jet in order to prevent damage to the thread in the carburettor casting. A gasket must always be used between the two halves of the carburettor.

SLOW RUNNING ADJUSTMENT

This should be carried out when the engine is hot; the minimum running speed is usually set around 550/600 rpm. A spring loaded adjusting screw is provided close to the throttle lever by means of which the exact throttle opening can be adjusted for idling. The head of this Screw should be turned clockwise to increase the idle speed and vice versa. The slow running mixture screw (12) will provide a richer idle mixture if turned in a clockwise direction by reducing the supply of slow running air. On the other hand if there is evidence of rich running, Le., black smoke from the exhaust when idling, this screw should be given a quarter, or one half turn in an anti-clockwise direction. The usual setting is about one complete turn open from channel (10) the full home position, but of course this varies slightly from one engine to another.

COLD STARTING
The rich mixture necessary to meet this condition is provided by closing the choke, or air strangler (3), and at the same time the throttle lever should be set about one-third of its full movement open. A few sharp pulls over compression with the starting handle will give an immediate start even in the coldest condition, provided all engine details are in order. Never leave the throttle in the slow-running position when starting a cold motor.

HOT STARTING
When the engine is hot or warm, the choke is not required and the throttle position is not important. If the engine does not immediately respond set the throttle open, as continued rotation might bring about an over-rich condition in the cylinder. When dealing with such a condition, it is advisable to remove the sparking plug and also the air cleaner. A few rotations of the crank-shaft will restore normal conditions in the cylinder, and upon replacing the sparking plug, the engine will fire and run in response to further rotation, provided the plug is clean and dry.

GENERAL

In most cases filter gauze is provided and this should be cleaned periodically by first of all removing the brass plug fixing the petrol pipe to the carburettor. Take care to replace the fibre washers when reassembling, placing one washer on each side of the petrol pipe banjo. If the complete carburettor is removed and dismantled for cleaning purposes, it is a good plan to blow it out on a compressed air line. When replacing the

instrument take care to use a thin flange gasket, as if a thick gasket is used it wilt tend to squeeze out, causing the flange on the carburettor to bend, and this may allow an air leak. Check the flange for damage of this nature, which can be trued up in the usual manner with a file. After replacing a carburettor, always cheek the air strangler, or choke, to make quite certain it closes completely when the control is operated and also that it opens fully, these points being most important. The throttle lever, if controlled by a speed governor, should work quite freely. Paraffin engines must be turned over to petrol for a few minutes before stopping in order that petrol will be available in the float chamber for re-starting. A drain tap (20) is provided on these models to drain off paraffin from the float chamber, if necessary. The air strangler plate (3) may be of the fixed type as shown, which usually has a small air hole, this being provided to ensure continuity of running after the first fire when starting under cold conditions. In certain of these carburettors, a fully automatic spring loaded strangler flap is used. The method of operation is the same in all cases. It is possible to use a variable main jet on certain engines this part is shown (22), and can be supplied upon request.

The makers’ adjustment of the carburettor gives correct mixture strength for all conditions, up to about 3,000 feet above sea level. When operating at high altitudes, it may sometimes be necessary to deal with rich running and loss of power. In such cases, one size smaller main jet will usually be found beneficial, however, if the power loss is still appreciable, it may be an advantage to fit a larger choke tube in conjunction with a suitable main jet.

Diagrammatic Section of Carburettor, Type 28G (with adjustable jet)

 GENERAL DESCRIPTION

The 28G carburettor, shown in the sectional view, is a vertical unit of robust design and construction, capable of high-angle operation.

OPERATION

Petrol enters the carburettor at the banjo union (7) and passes into the float chamber through the needle and seating assembly (14). It will be observed that the float chamber Of bowl is of special construction, embodying a dual float (12) system; as fuel rises in the chamber the floats will be lifted unti!, at the predetermined level, they will press the needle on to its seating and thus prevent the entry of more fuel.

The channel (2) in the illustration is plugged as shown. On this model the air vent to the float chamber is taken from the inside of the air intake, via the annular space round the choke tube, to the carburettor bowl.

From the float chamber the petrol will pass the tip of the adjusting needle (13), through the main jet (19), and then rise in the main discharge tube (9), slow-running jet (10) passage and main air bleed (6) channel to the correct level.

STARTING FROM COLD

By extending the appropriate control. the strangler (18) turns and closes the air intake of the carburettor. In so doing the interconnection rod (8) will automatically open the throttle (5) to a degree found most suitable for starting purposes. The engine is

then turned over and a very rich mixture will pass to the engine to provide the necessary fuel for starting purposes. Once the initial fire has been obtained, the extra depression on the engine side of the strangler will cause the spring blade in the strangler to open and close rapidly with the engine pulsations. This is to ensure that the engine continues to run at a good speed once the initial fire has been obtained. As soon as normal working temperature has been attained the strangler is released and, with the throttle in the normal idling position, fuel is delivered by the slow-running system.

IDLING

Petrol is drawn from the well beneath the idling jet 10), is measured on passing through the jet and then enters the bore of the carburettor through the idle drilling (3) on the engine side of the throttle. Progressive opening up from idling is ensured by the provision of a second feed hole, slightly below the  idle outlet (3).

MAIN CARBURETTOR

When the throttle is opened, petrol in the channel beneath the air bleed (6) will be drawn into the engine, and the main air bleed will now be effective over the whole speed range. Petrol from the float chamber is metered by passing through the main jet (19), after which it enters the bore of the carburettor from the tip of the main discharge tube (9). At this point the fuel is taken up by the air from the intake of the carburettor, and the mixture then proceeds to the engine via the choke tube (11).

As with all carburettors, the keynote of reliable and efficient service is absolute internal cleanliness. If the float chamber drain tap (15) is not utilised when starting from cold, it is recommended that it should be opened occasionally when the tractor is in use, in order to clear away any foreign matter or water which may have collected at the bottom of the float chamber.

The combination of choke tube, main jet and air jet as specified overleaf will be found correct, and it should not be necessary to alter these parts when dealing with ordinary maintenance. It will be observed, however,

that the main jet is adjustable by means of the needle (13) and very careful setting of this is necessary for local conditions.

The idling adjustment is a matter of setting the throttle stop screw (4) and the air regulating screw (1) to ensure that the engine speed and fuel mixture are correct to obtain steadiness when idling. Turning the regulating screw (1) clockwise provides a richer mixture for idling, and vice versa.

In any case of difficulty, the Zenith Technical Information Centre is at your disposal, or the nearest official Zenith service station should be consulted.

Diagrammatic Section of Carburettor, Type Climax

The 30VEA carburettor is an updraught model of the V type Zenith carburettor incorporating an easy starting device, and has been specially modified to make it completely dustproof. All the air used by the instrument is taken from inside the air intake, and there are no exterior holes open to the atmosphere. (The diagrammatic drawing right does not illustrate this feature but shows a normal Zenith model, although it is correct in all other respects).

THE STARTING DEVICE

When starting from cold the control knob on the dashboard is pulled out so that the valve 2 opens (as shown in the diagram.)

When the crankshaft turns over the accelerator pedal must not be depressed, as it is essential that the throttle should not be opened beyond the normal idling position for starting purposes. When the engine rotates with the throttle in this position the depression created will be concentrated upon the outlet 1 on the engine side of the throttle. It will also be apparent at the venturi 4 and in the communication tube 10, with the result that air is drawn through the venturi and petrol from the control jet 12 and starting jet 14.

The petrol will meet the air at the venturi and be broken up to form a rich starting mixture, which then passes into the induction pipe through a channel above the throttle.

A weaker mixture may now be used, but even so it must still be richer than that provided by the main carburettor. Once the petrol in the starting well has been consumed it will be replenished with a measured quantity of fuel from the float chamber through the starting jet 14. With the bottom of the control jet tube 12 uncovered, however, the depression on this tube will be partly broken by the air leak at 13. This gives the desired weakening off once the cold engine fires and continues to run.

When the engine reaches a normal working temperature, the extra fuel supplied by the starting device can be dispensed with. The starting control knob is released and the valve 2 doses, thus cutting off the depression that previously caused the starting device to operate.

SLOW-RUNNING

With the engine running and the throttle in the idling position a depression will be concentrated upon the outlet 1, and consequently also on the slow-running jet 6. As a result petrol will be drawn from the well beneath the jet, measured on passing through, and proceed to outlet 1; here it will meet the air passing the edge of the throttle and be carried into the engine as a suitable mixture for idling purposes.

At the throttle edge there is a further outlet 5, which breaks into the slow-running passage. Upon the throttle being opened from the idling position this drilling will enable an additional mixture to be provided to ensure a progressive get-away from slow ­running. (This explains the name of the progression jet 3.)

Upon the throttle being opened still further the depression will be concentrated upon the nozzle of the emulsion block 11, which projects into the smallest part of the choke tube. This will result in petrol being drawn from the main channel in the emulsion block, which is supplied by the

passage beneath the slow-running jet 6 and the well of the capacity tube 8. This reserve is provided to ensure immediate get-away when the throttle is opened. Once this reserve of petrol is used the supply will be direct from the float chamber, being metered through the main jet 16 and compensating jet 15 before leaving the nozzle of the emulsion block.

lt will be realised that as soon as the petrol in the float chamber falls below the predetermined level the floa t will fall with it, thus permitting the needle 9 to drop away from its seating, and petrol will pass into the chamber from the fuel line.

The petrol feeds the carburettor through the banjo, filter and filter piug as shown in the diagram. As it enters the float chamber it win raise the float and push the needle on to its seating, thus cutting off further supplies when the correct level is reached.

SLOW-RUNNING ADJUSTMENT

There is an adjustable air release to the slow-running jet which is controlled by the screw 7; this varies the quality of the idling mixture. When the screw is turned clockwise there is a greater depression upon the slow running jet, and as a result a richer mixture is obtained for slow-running.

Alternatively, if the screw is turned in an anticlockwise direction there is a reduced depression upon the jet, and consequently less petrol is drawn through it.

To adjust the slow-running speed (I.e., the volume of the mixture) the throttle stop screw at the throttle lever may be turned clockwise, causing the throttle to open wider and give a faster idling speed. On the other hand, if the screw is turned anticlockwise the throttle will close to a greater degree and reduce the idling speed. It will therefore be seen that to obtain good slow-nmning it is necessary to adjust both the air regulating screw 7 and throttle stop screw.

DIFFICULT STARTING

Many factors have to be considered when there is difficulty in starting an engine from cold. After all other possibilities have been eliminated the following points should be checked in the carburettor

ENGINE FAILS TO FIRE

A too-weak mixture is the most probable cause, and adjustments to the control jet and starting jet are indicated. The control jet measures the petrol flow until the fuel in the well is consumed, and thereafter affects the depression on the starting jet. First, try larger starting jets, but failing improvement resort to increased sizes of control jet. Engine fires but then stops.

Over-rapid weakening-off is the fault here, and correction is to be found by increasing the size of the starting jet. (N.B.­The concentration of the depression upon the starting device is most essential. Make sure, therefore, that the throttle is closed to the idling position when the engine is being started).

When the carburettor is worn it will be impossible to obtain good slow-running, but it must also be remembered that there are other factors which, quite apart from the carburettor, have an influence upon slow­ running. These include joints that are not airtight, worn valve guides, valves not seating, over-advanced ignition, incorrect setting of sparking plug points, etc.

GENERAL

To remove the float-chamber unscrew the two bolts, when it will be found that the main and compensating jets inside the bowl have square recesses into which the squared end of one of these bolts can be inserted in order to take out the jets.

Do not pass anything through the drillings of the carburettor or the jets that is at all likely to damage them. The safest way of clearing an obstruction is to swill the part in petrol and clear with air pressure.

Periodically inspect the emulsion block screws, needle seating, jets etc., and see they are all tight and secure.

It has now been observed how the petrol reaches the jets and channels. The fuel will occupy the position described all the time the engine is not running.

STARTING

Let it now be supposed that the engine is to be started from” cold.” The strangler control on the dashboard is extended, which causes the strangler flap to close off the air intake of the carburettor.

With the ignition switched on, the engine should now be turned over by means of the starter, ensuring at the same time that the throttle control is not opened from the closed position. The necessary part opening of the throttle for starting having been provided automatically by the interconnection mechanism between the strangler and the throttle. Practically all of the depression caused by the rotation of the engine is now concentrated upon the progression and the slow running outlets (22 and 24), and because of the partly opened throttle plate, upon the outlet (19) of the emulsion block. Very little air enters and consequently a very rich mixture as required for — cold ” starting purposes is made available to the engme.

The engine will now fire, and as soon as it does so, the engine speed will increase and heavier depression will cause the valve in the strangler flap to open. The result will be to weaken the mixture and ensure that the engine continues to run once it has fired,

As the engine warms to its work the strangler must be released and the engine will be operating on the normal mixture.

NORMAL OPERATION

With the throttle closed down to the idling position the mixture will be supplied from

the slow running jet (10). Depression will be concentrated upon the outlet (22) and upon the slow running jet (10). Here there is a controlled depression fall because of the leak at the slow running air regulating screw (23).

Petrol will be drawn from the well beneath the jet, measured on passing through, before continuing to the throttle edge.

At the throttle edge there is a further outlet (24) which breaks into the slow running passage. Upon the throttle being opened from the idling position, depression will be concentrated here and a progressive get-away from slow runnmg is assured.

Upon the throttle being opened still further, the depression will be concentrated upon the nozzle (19) of the emulsion block which projects into the narrowest part of the choke tube. This will first result in petrol being drawn from the passages (17, 16, 14, 13 and 9), as there must be a ready reserve of petrol available for instant acceleration.

The source of petrol supply is eventually through the main and compensating jets (7 and 8). It will be observed that the petrol in the well of the capacity tube (9) has been consumed, and as the top of the well is open to atmosphere, petrol issuing from the compensating jet along the passage (14) will now be broken up at (16) by air from the capacity tube. Petrol issuing through the main jet (7), along the passage (13) will meet the emulsified petrol from the compensating jet in the common channel (17). This will tend to break up the petrol from the main jet also. The supply from both sources will then be drawn from the emulsion block nozzle into the choke tube.

Published in Journal No.41, Summer 2002, Alan Dunderdale

Where on earth does it go? Petrol, that is. First task in the mystery is to stop the carburettor leaking – that’s got to help.

Clearly the carburettor leak had been long standing given the amount of blue gasket sealing gunge. A carburettor repair kit duly arrived and seemed straightforward enough at least that’s what I thought when I started.

The items of the repair kit laid out.

I removed and dismantled thecarb and set about tapping out the throttle linkage bushes to fit the new ones that came with the kit but they wouldn’t budge. [ tried drilling them out, thankfully with a smallish drill bit. My logic was that the drilling action would loosen them and they would pop out: it’s worked in (hc past. To my horror I realised [ wasn’t drilling a bush out but the carb casing itself. Oops.

I know from past experience really accurate drilling isn’t my forte so [ popped down, rather sheepishly, to my local friendly tractor shop (Vincent Tractors). Thankfully they kindly drilled the carb to accept the new bushes. A relief.

The newly fitted over long white bush can be see protruding from the carburettor on the left hand side.

Strangely the bushes are rather too long. The white bush can be seen sticking out on the photo and I could see no alternative but to shorten the one that abuts the throttle linkage as it could not be assembled at its full length. That done and still wondering if there was going to be an unintended consequence I assembled the carb and refitted it. Wonder upon wonders suck, squeeze, bang straight away and no more leaks from the carburettor. I still don’t know where I was supposed to put all the washers in the kit as I only used a couple.

Controlling the revs is a bit of an issue though. During my tenure the throttle has always been a bit jerky in operation and no amount of easing and oiling the linkage has helped. It is a fantastic design – and I don’t mean that in a complimentary way – Mr Heath Robinson would be proud. Quite what to do with it I am not so sure but wonder whether the vertical sprung link at the front should be split and kinked as can be seen on the photo.

Throttle spring and linkage.

However for the moment I am still on a mission to understand where the fuel is going. My latest test was to pour I litre into the tank and immediately drain it out through the tap on the carb: all without troubling the engine. All I got out was 800ml. And, yes the filter glass was full before I added the 1 litre test amount and was still full at the end. It is not escaping, as 200ml would make quite an obvious puddle. My only thought so far is that it is leaking from the petrol tank into the TVO one but if it is going one way then surely it should come back through the same means. The inside of the TVO tank does indeed look damp ­as well as disgustingly rusty – and I have somewhat unsuccessfully so far tried drying it out so I can see whether it gets damp when I put fuel in the petrol tank.

That aside, I did get a great boost in the post. A nice new V5 and age related registration number – yippee!! And thanks again Duncan, the Club’s esteemed DVLA Registration Officer. A brilliant job done.

My local garage quoted me £30 for a number plates and I duly handed the money over. However they rang me back the following day to tell me it was £30 each. Even he thought that was too much. EJ plates on eBay came to the rescue at £20 for the pair, good quick service as well. I wasted no time making up a rear bracket and fitting them both.

‘Twas exhilarating driving it down the road and for the first time moving beyond first gear. I only went about 50 yards and turned round getting back seconds before my litre of fuel ran out. Phew.

Back to the beginning, where on earth is it going?

The rear number plate bracket is starting to take shape.

Additional Search Keywords: TEA TEA20

Published in Journal No.101 Summer 2022, Trevor Pepper

In my last article I said I would next look at the basic difference in various engine types.

TE-A – petrol engine up to 170,000 – this engine has 80mm bores, equal sized inlet and exhaust valves and the water pump mounted on the cylinder block. There is a plain part of the cylinder head between No.4 and 5 push rod tubes (see fig 1). The cylinder head is 3½” thick. Compression ratio 5.77:1.

TE-D – TVO engine introduced at engine No. 120,500 and up to 170,000. This TVO engine has 85mrn bores, inlet valves are larger than the exhaust and the water pump is mounted on the block. The cylinder head has a square tube cast into the cylinder head, between No.4 and 5 push rod tubes (see fig 2). The head is 3¾” thick. Compression ratio 4.8:1.

TE-A petrol – 170,000 onwards. This engine has the bores enlarged to 85mm (same as TED) and the water pump is mounted on the head. Fig 3 shows the strengthening of the head for the pump mounting bolt, the cylinder head also has the cast square tubes, as TED. Internally, the inlet valves are larger than the exhaust and the thickness of the head is increased to 3¾^“. Therefore, externally the TEA and TED now look identical. However, internally there are variations. Firstly in the shape of the combustion chambers as shown in figs 4 and 5. The compression ratio is now 6:1.

TE-D – 170,000 onwards the difference between these and the earliest models are basically the pump on the head and slightly higher compression ratio of 5:1. There are also slight variations in the following items fitted to a TED:

• Thermostat and its housing
• Throttle rod assembly
• Carburettor and fuel tap D.
• Distributor and timing.

All TE-D’s have a heat shield fitted over the exhaust and inlet manifolds and a dual fuel tank.

In the next issue I will deal with the many conversions which were available in the early 50’s.

Published in Journal No.31 Spring 1989 – Arnold Staples

These notes, by Harry Jeffery, may be useful to those of us who still use our TE-Ds (which run on Tractor Vapourising Oil or TVO), TE­Hs (Lamp Oil or LO) or those engines con­verted from petrol to TVO, and wish to get the best out of these fuels whilst minimising sump oil dilution.

In the mid fifties a Service Bulletin was issued detailing modifications which would improve the perfomance of VO engines and its ability to vapourise fuel efficiently. The main items to note were:-

1. Use the correct spark plug with correct gap. Set wider rather than closer, say .030″­.035″ for Va/La (.032″ for va conversion)
2. Make sure that the exhaust manifold is completely free of all carbon deposits, espe­cially those moist oily ones. This may be done by burning out with an oxy/act. torch or by shot blasting. A combination of the two proved to be the most effective. Always use a non abrasive grit.
3. Make (from aluminium sheet) a sup­plementary shield to fit under the existing standard manifold shield, thereby deflecting

the fan draft away from the manifold. For the same reason, fit another shield in front of the carburetter throat.

In addition, see that the ignition is in good order with correct timing and the carburetter correctly adjusted according to type. The Zenith 24T-2 always gave best results. The Zenith 28G was a menace unless modified. The Holley 859A carburetter, mainly fitted to the 80mm engines, was not so reliable as the Zeniths.

For normal work the Zenith 28G requires 1 turns for the main jet on petrol, another turn on TVO and yet another turn for lamp oil, whereas the 24T-2 main jet setting remains the same for all three fuels. However, the main jet size on the ‘Fully Variable Type’ 24T-2 is 1 mm for petrol and 1.05mm for Va/La fuels.

The petrollTVO conversions should be fitted with a different sparking plug [Cham­pion L.8] to the production TVO/LO engines. Full details can be found in the workshop service manuals available from Landsman’s Postal Bookshop or Massey-Ferguson. Edi­tor)

Published in Journal 15, Vol.4 No.3 Winter 1991, Harry Jeffery.

FE35 with TVO Engine

Dear Sir,

I recently acquired a Massey-Ferguson FE 35 tractor with a TVO engine. The previous owner used to run it on 6 parts of paraffin to 1 part of petrol.  The tractor is used for light duties, such as hauling logs and a trailer. I have only run it on petrol, but have found the fuel consumption to be high.  I should be grateful if you would advise me if the paraffin mix is acceptable. If not, what should I use to improve the fuel consumption?

Thanking you in advance of an early response. R P Thatcher

Engines designed to run on Tractor Vaporising Oil (TVO) or paraffin (lamp oil or LO) have a much lower compression ratio than those designed to run on petrol. It is thus quite usual for such engines not to be fuel efficient when running on petrol alone.

Before TVO became available, on this farm from 1928 we always added petrol at the rate of 1 gallon to 4 of paraffin. TVO was a great improvement but sadly we have had, in recent years, to revert to our pre-war practice. We usually add a pint or two of diesel or a very light oil such as Castro I GTX to aid upper cylin­der lubrication.

It is always important to ensure your engine is at proper operating temperature before turning over to paraffin. Lamp oil engines, not usual in UK, are designed to run on straight paraffin. Avoid prolonged idling or very light loadings at all times when on paraffin. Such engines are best at normal operating loads. Hard work but not overloading is ideal.

It is also worth checking that your carb, air­cleaner and related pipework are in good order, clean and properly serviced.

Service Department

Letter and Reply published in Journal 21, Vol 7 No.1 Spring 1994