REBUILDING YOUR ENGINE?

CHRIS WITOR 117/29 February ’01
 
How to make a really clean start, plus some advice on lubrication and oils

WWW.CHRIS WITOR.COM Triumph 2000, 2500, 2.5 Specialist Parts SupplierI would regard cleanliness of the components as the most important aspect of an engine rebuild, in particular the block and its oil galleries. Any residual machining particles or dirt in the oil galleries can get pumped straight into the bearing journals of the mains, big ends, camshaft and rocker shaft. Damage can be costly in terms of either premature wear or even total bearing failure resulting in another rebuild.

Crankcase

Dirt in the crankcase should not find its way into the oil galleries, as no particles below 15 – 20 (metric) microns (i.e. 0.0005906 – 0.000787 inches) should pass through an industry standard oil filter, unless the filter is so clogged that its by-pass valve opens. I have seen an instance where the inner O-ring was not fitted to a spin-on oil filter conversion, resulting in rapid wear to the bearings on a rebuilt engine, as the oil by-passed the filter picking up more and more debris, as more and more wear took place! Apart from this, dirt in the crankcase small enough to pass through the strainer of the oil pump will wear the lobes of the pump rotors.

Another less obvious place that crankshaft dirt particles end up is embedded in the seat of the oil pressure relief valve in the block itself, preventing the valve plunger from seating properly. The valve itself can stick open even further off seat. Soft, substandard reproduction valves are especially prone to this as particles embed into the soft metal more easily. The Original, and properly remanufactured, valve plungers have a hardness of around 40 Rockwell B. A stuck open valve can result in a sudden large loss of oil pressure, whereas particles on the seat in the block cause consistent low idle pressure, particularly when the engine is hot. A good rebuilt engine should idle at between 25 and 30 psi when hot. If less, and the rest of the engine is in good condition, it is worth cleaning the oil pressure relief valve seat in the block.

I had this tool made to clean the seat. It is made from a 9/16 inch drill bit shortened and reground to 118°, the angle of the pressure relief valve seat in the block. The cutting edge angle was reduced, so that this works more like a scraper than cutter. The tool is turned by hand using the wrench shown. It is surprising what granular debris comes off the seat in some blocks. The more dirt that comes off, the larger the increase in oil pressure.

It is not only the block itself that will harbour dirt. The following components should also be cleaned thoroughly:
Rocker cover (including internal gauze in later versions)
Rocker shaft assembly
Cylinder head
Engine front plate
Timing cover
Bridge piece across n01 main bearing cap
Timing sprockets
Sump
Rear oil seal housing
Crankshaft
Connecting rods
Main bearing caps and bolts
Pistons
Camshaft
Pushrods
Cam followers
Distributor/drive gear and pedestal
Petrol pump (where used)
Oil pump
Oil filter adaptor or housing
Cleaning the Crankcase

Some engine reconditioners offer a service where the whole block is immersed in powerful cleaning agent. H T Howards of Slough use a “decarbon fluid” which removes all external traces of oil, gunge and even paint from the block. This saves a lot of physical scraping, scrubbing and brushing, especially if the block is covered in thick, sticky, black gunge.
After degreasing, I mount the block on an engine stand, and remove any surface rust with a rotary wire brush, so that the block is ready for painting later. The core plugs are also removed at this stage. I prefer to use an oxyacetylene cutting torch to remove the plugs, simply heating around the edges to red heat and blowing a hole in the middle of the plug. When cooled, they will have lost their interference fit. A screwdriver is inserted into the hole, then the plugs can simply be levered out. I prefer this to any hammer and chisel method, as there is no risk of scoring their housings.

Tool to clean oil pressure relief seat

Oil pressure relief valve, spring and nut in special blue anodised alloy. Steel nut weighed 110g (Alloy 40g)

However, despite the block being clean externally, it is never to be assumed that the internal oil galleries will be clean enough for use. The main oil gallery that runs the full length of the block should be thoroughly cleaned. The distributor/oil pump drive bush should be drifted out using a 1/2 inch shouldered drift such as a 1/2 inch socket cap bolt. This is drifted up out from its underside.

Oil pump/distributor drive bush,
Left – late Mkl & all Mkll Right – early Mk I

The 1/4 inch BSP plug (O/E no 118632) is removed from the rear of the block using a suitable Allen key. The plug at the front of the block is a bit more tricky to remove. I drill a 1/8 inch hole through the middle of the plug. I then use an oxyacetylene torch with its intense localised heat on the aluminium plug until it just starts to melt. The plug tries to expand but has to expand inwards as the block prevents expansion outwards. When it cools it contracts leaving a loose fit in the block. I then lubricate the thread with penetrating oil, drive a flat bladed screwdriver into the soft plug and simply undo it.

Front 1/2 inch UNF oil gallery plugs, OE No PS1103 supplied on a stick of 10, removed piece above

The six 1/8 inch BSP plugs (O/E no 118686) can be removed from the side of the block using a 3/16 AF Allen key. If struck a sharp blow with a hammer and punch, they will normally break their hold. If this fails heat up as with the front plug.

With all the plugs removed, a rifle brush and extension can be passed through the main gallery. Wash the brush in degreaser after each pass. Rifle brushes can be purchased from a gun shop. I made my own extension out of a piece of 5/16 inch old and 24 inch long rod. I use a combination of appropriate drill bits – turned by hand – and thread taps: 1/8 and 1/4 inch BSP to clean out the cross drillings to the cam and main bearings. A 5/16 inch UNF tap is useful to clean out the many other threads of this size on the block.

Rifle brush and extension used to clean main gallery

Next, the block is given a thorough flush as follows:
The oil pump bush is drifted back in with a shouldered bush. Don’t drive the bush too hard as the flange nears the block as the flange can be broken off. The old pump is refitted and the block placed in a domestic water tank (cost less than £10 from a DIY superstore). The block is supported on some wooden blocks so that the strainer of the pump is just above the bottom of the tank. The oil filter and the pressure relief valve and spring are also refitted.

Twenty-five litres of new degreaser (available from any good motor factors) are emptied into the tank.

A shaft will be needed to engage the tongue and groove drive of the oil pump. A PI distributor/metering unit shaft with the gears removed is ideal. If not available make a shaft out of a 6 inch length of 1/2 inch old bar with a groove cut out to engage in the tongue of the pump. The pump turns anticlockwise when viewed from above, so a reversible electric drill with a 1/2 inch chuck will be required. I usually run the drill for about 10 minutes, swapping gallery plugs around to divert and intensify flow of degreaser through the galleries.

Remove the oil filter and pressure relief valve. The engine can be removed from the tank and put on a table, or ideally, on an engine stand to wash with hot water. Dry with a blowlamp and paint with engine lacquer. I usually put a magnet in the bottom of the tank to see how much ferrous matter has been washed out of the block. The degreaser can then be salvaged for more basic tasks. When the paint is dry the gallery plugs can be refitted to the block.

I always use a drop of Loctite pipe sealer (available from engineering or bearing suppliers) on their threads. Refitting the plug to the front of the block isn’t so straightforward. The intended stick of thread (PS1103) tends to wind far further into the block than the original, which is not reassuring. I use the 1/2 inch alloy rod that comes with a Kenlowe fan kit and run about 3/8 inch of 1/2 inch UNF thread onto the end of the rod with a circular split die and die stock. By this method the thread is more tapered. It can be wound into the block after being covered with pipe sealant, cut off flush and filed flat.

Forged blue anodised alloy blanking plugs. Adds a nice touch for the discerning engine builder
Other useful tips

If the engine has had the bores honed, or has been rebored, and new piston rings fitted always run the engine in on special running in oil. This helps the piston rings to wear/bed to their bores preventing glazing and thus premature oil consumption problems. Normal oils contain anti-friction additives which are detrimental to running in. I use Comma R05L. When the engine is installed in the car and filled with oil the reversible drill and pump drive can be used to prime the galleries, pumping oil into all the bearings and the rocker shaft before the engine has even turned.

Magnetic sump plugs, before use
Magnetic sump plug with ferrous particles collected

When the assembled engine is first run with new piston rings on honed bores, a lot of ring swarf will be deposited when the peaks of honing marks wear into plateaux as the rings and bores bed in. At this stage a magnetic sump plug is highly beneficial which will pick up a lot of grey metallic paste, especially for the first 1000 miles after which the running-in oil should be changed.

Oils

Mobil 1 5w/50 synthetic oil is great for our engines, but has been superseded by thinner 10w/40 which I first tried on a high mileage 2000 engine. Oil consumption became unacceptable! My (since rebuilt) 2000 is now on Comma (who own Mobil) synthetic 5w/40, which I am evaluating. Oil consumption is no longer a problem. Modern engines use thinner synthetic oils because they create less drag, improving power output and fuel economy. If f were going to use a 2.5 engine to do a lot of heavy towing in a hot climate I would use Castrol RS10w/60. 2.5 engines run a higher crank bearing load with their longer stroke than the shorter stroke 2000. One can, of course, use cheap old 20w/50 non-synthetic oils which are relatively high in tars and waxes creating drag and thus need replacing more frequently than modern synthetic oils. Semisynthetic oils offer a good compromise.

Engine – Engine rebuilds

I don’t regard any of the oils I know of as being totally ideal. There are many compromises involved. I would ideally prefer to try 5w/45 on my 2000, which, as far as I know. doesn’t exist. However. the oil pressure does not drop below 20 psi when hot on 5w/40. The greater flow rate of a thinner oil will help cool the bearings more than a thicker oil, but a thinner oil has a lower film strength. The lobes of a high lift cam would be my greatest concern, if the oil were too thin.

It will be interesting to hear what oil other club members are trying.

Oil Coolers

These are less necessary with modern synthetic oils which are designed to cope with lubricating a hot turbo charger. A temperature gauge can be used to evaluate the situation. Cleanliness of oil cooler. hose and thermostat is essential as any dirt will be pumped straight into the oil galleries and bearings. In most cases the oil is filtered before it passes through the cooler.

Oil Pump

Very much at the heart of the matter, I wrote about this in my first Technical Article seventeen and a half years ago. (See first Register Service Notes page 1.151.) The key point for attention is rotor end float. Getting down to one thou of end float was a bit optimistic. 0.001 – 0.0025 inches is more realistic. If you have a new pump with more end float than this (0.004 -0.006 inches isn’t uncommon) then it will be beneficial to have the body machined or simply use a blue printed pump to start with.

DECARBONISING A SIX CYLINDER 2000 MK1 ENGINE – PART 2

88/16 April ’96

Having stripped, cleaned and prepared the engine for decoke and reground the valves as described in the last month’s article, the engine has to be rebuilt and tuned.

The refitting of the valves into the cylinder head is the reverse of the procedure for removal, using the spring compressor in the same way. Remember to fit the close coils of the spring towards the cylinder head. The valve springs should be checked before replacing. The easiest way of checking a valve spring is by comparison with a new one. Do not be misled by the difference in free length of the spring as this does not always have any bearing on their load at the fitted length. The best way of testing springs is to place a new and an old spring into a vice, end to end, with a flat piece of metal between them. Determine the fitted length of the spring by placing a valve into the cylinder head complete with cotters and caps, but less the spring. Measure the distance between the two faces on which the spring rests. This distance will be the fitted length. Tighten up the vice with the two springs in opposition until the new spring is compressed to the fitted length. If the old spring is then shorter than the new spring this indicates \weakness.

Remove the carbon deposit from the crown (or top) of the piston leaving a ring around the outer edge of about 1/2″. A certain amount of carbon will have formed round the edge of the piston inside the bore. By removing the carbon to the edge of the crown, this ring would be broken which could cause heavy oil consumption. When removing from the top of the piston take care not to damage the piston with a sharp instrument such as a screwdriver. Stuff some clean rag into the openings on the nearside of the engine to prevent the particles of carbon from getting onto the cam followers. The hard carbon will cause uneven wear on the cam followers, which in turn will cause noisy tappets.

Refit any studs which may have come off with the cylinder head nuts and check those in the head for tightness. (I find it much easier to clean the top of the block with the studs removed. Uncle Stan Part) Clean all the flat faces of the cylinder head and the top of the cylinder block in readiness for re-assembling and remove the rag from the cam follower chest. Place the cylinder head gasket on to the top of the cylinder block. The gasket should first be coated with nonhindering gasket cement or grease. (I always use grease. Gasket cement can ‘blow’. – USP) Always fit the gasket with the seams uppermost.

Replace the cylinder head, nuts and washers remembering to use the high tensile nuts and tighten down. Cylinder head nuts should always be tightened evenly, starting from the centre and working outwards towards the ends. If a torque wrench is available tighten the nuts down to the correct torque. (The Mark 1 engine is prone to blowing head gaskets because the studs are too small to allow it to be tightened down effectively. This was fixed on the Mark 2. It is therefore IMPERATIVE that you use a torque wrench, and tighten the nuts down to the maximum recommended setting (46 lb. ft.) in the recommended order. You must also be sure to tighten down all of the head nuts again after 100 miles. Unfortunately, this entails removing the manifolds. But nobody said life was easy. – Uncle Stan Part)

When the head has been refitted and tightened down, the push rods can be replaced. The push rods are better if kept in order. Fit and secure the rocker shaft assembly, making sure the cups of the push rods are located on the ball pins on the rockers. The rocker pedestal nuts again must be tightened evenly to prevent bending of the rocker shaft.

As the cylinder head, valves and rockers have been disturbed the tappets will have to be reset. There are many different ways of setting tappets, the most popular method being the 13 method. Number the valves 1 -12 starting from the front. Rotate the engine a few times to give the valve and rocker gear a chance to find their natural position and check their action. To set the tappets look for the valve which is open, the one where the spring is compressed, subtract the number of that valve from 13 and that will tell you which tappet to adjust. Slide a 0.010″ feeler gauge between the top of the valve and the rocker. The adjusting screw can be tightened or slackened so the feeler gauge is a slide fit between this valve and rocker. Rotate the engine so the next valve is open and adjust the corresponding tappet; repeat this until all 12 tappets have been adjusted.

Place the manifold gasket onto the studs the correct way round; on close examination it will be found the rear stud hole is lower than the front. If fitted wrongly blowing will take place at a later date. Before fitting the manifolds unscrew the nut joining the inlet to the exhaust manifold. Clean off any remains of the old gasket and renew the carburettor joints. After fitting the manifold tighten the nuts and bolts with their retaining plates, tighten the nut joining the two manifolds. Reconnect the exhaust pipe using a new gasket and if the front mounting has been slackened, re-tighten it. Refit the throttle and choke controls to the carburettor and check their correct function, replace the air cleaner.

Either clean or renew the distributor points, setting the gap to 0.015″ when the fibre heel is on the peak of the cam. Clean and reset the spark plugs and if they show any sign of burning on the electrodes renew them. The plugs should be set at 0.025″.

Replace the spark plugs and distributor top. Make sure the correct lead from the distributor top is connected to the correct plug; this is made easier by marking the leads. Re-connect the H.T. lead to the coil.
Renew the gaskets on the water pump and thermostat housing and refit the pump to the head securing at the same time the petrol pipe and dynamo/alternator stay. The petrol pipe can then be connected to the carburettors. Prime the petrol pump with the lever on the side of the pump and examine for leaks. Examine the radiator and heater hoses for cracks or perishing and if necessary replace them. A light smear of grease on the inside of the hoses makes them easier to fit. Refill the radiator and cooling system with clean water, or with the old coolant if it contains antifreeze and has been kept. Examine the radiator filler cap and check the small valve in the centre. Check the seal in the top of the cap.

Place the fan belt around the pulleys and re-connect the dynamo/alternator stay. Pull the dynamo/alternator away from the engine, this will tighten up the fan belt and finally tighten the dynamo/alternator mounting. Join up dynamo/alternator wiring and temperature gauge.

Before replacing the rocker cover oil the rocker assembly and fit a new gasket to the cover. Do not over-tighten the rocker cover nuts as this will distort the cover and cause leaking.

Check that all items have been reconnected and finally reconnect battery. Run the engine for a little while until the normal working temperature has been reached. All that remains is to tune carburettors.

DECARBONISING A SIX CYLINDER 2000 MK1 ENGINE – PART I

87/16 February ’96

GENTLE WARNING

This series of technical articles has been designed for the “mechanically minded” reader who feels capable of carrying out his own maintenance to this degree. If you have doubts about your ability to cope with the instructions you are earnestly advised to leave the job in the hands of an experienced mechanic. During the combustion of the petrol air mixture of an engine, deposits of carbon are formed. Although the majority of these deposits are ejected through the exhaust system, a certain amount remains and collects on the walls of the combustion chamber, valves and piston. This build up of carbon prevents the engine from breathing and robs it of its performance, in the same way a fire loses its brightness when the chimney becomes blocked with soot.

Very high temperatures are also produced during combustion, which are necessary for the running of the engine. The high temperature and heavy loads exerted on the valves will sometimes cause them to burn after very big mileages. The question now arises as to when a decoke and valve grind are necessary. To give an answer in terms of mileage on this question is virtually impossible, as no two engines are alike. The best guide is in the symptoms; the loss of compression is the key. Loss of compression will cause loss of power, heavy petrol consumption, difficult starting and uneven running, and even misfiring. As the fall in performance is gradual it is often not noticed until the condition gets very bad.

EQUIPMENT REQUIRED
1. A set of ring and open-ended spanners from 3/8″AF to 3/4″AF.
2. Valve grinding stick.
3. Screwdrivers, one large and one small.
4. Grinding paste, coarse and fine.
5. A scraper or rotary wire brush if available
6. Valve spring compressor.

SPARES REQUIRED
1. A set of decoke gaskets.
2. A set of exhaust valves.
3. Spark plugs, points, and hoses etc. as and if required.
Obtain your spares from a Triumph parts supplier and always quote your engine or commission number you are then certain of getting the correct parts.

REMOVAL OF THE CYLINDER HEAD

Whenever working on an engine the first safety precaution to be carried out is to disconnect one of the battery leads.

There are quite a lot of components connected to the cylinder head and other parts of the car, these all have to be removed or disconnected. Drain the Cooling system by the tap on the lower tank of the radiator (if fitted). All the hoses can then be removed including the heater hoses and manifold heating hoses on the Triumph 2000. After unscrewing the clips, give the hoses a twist to break the seal. This will make them easier to remove. Slacken off the dynamo / alternator mountings and remove the fan belt. The water pump can now be removed by unscrewing the three securing bolts, the top right hand bolt also secures the dynamo / alternator stay, the left one the petrol pipe. All three are just above the water pump pulley.

There are only a few electrical points which require disconnecting. These are simply the water temperature gauge, if one is fitted, and the H.T. leads to the sparking plugs. To save damage, remove the distributor top. It is also a good idea to number the leads, thereby preventing them from being connected to the wrong plug.

The carburettors can be removed with the manifold as a complete unit or separate. Disconnect the throttle, and choke controls, remove the air cleaners and disconnect the petrol and vacuum advance pipes. If the manifold and carburettors are being removed as a unit, disconnect the exhaust pipe. A single row of bolts and two nuts, one at each end secures the manifold to the head, these can be removed and the manifold lifted off.

Having removed all the controls and components from the head we can now start removing the head. Unscrew the nuts securing the rocker cover; these have fibre washers and plain washers under them, the fibre washers to prevent oil leaks. Removal of the rocker cover gives us access to the rockers themselves. The rockers are mounted on a shaft and are removed as a complete assembly which is secured by 9/16″AF nuts, one on each pedestal. From each rocker there is a push rod connecting it to the cam follower. When removing the push rods give them a shake, this will free them and prevent dislocation of the cam followers.

With the rocker shaft and manifold assemblies removed we can now have access to the cylinder head nuts, which can now all be removed. The cylinder head nuts are all high tensile nuts and should not be mixed up with other nuts of the same size, so keep them separate. If in doubt about the correct nuts, the high tensile nuts are identified by the letter “R” on the upper face.

The lifting can sometimes be difficult to start with, as sticking sometimes takes place between the faces of the head block and gasket. A slight sideways tap with a piece of wood or soft hammer sometimes helps. The cylinder head removed and on the bench, we can now concentrate on the valves. Removal of the valves from the head is one of the most difficult tasks to be encountered on the decoke.

A special tool is used to compress the spring; this relieves the pressure on the two collets allowing them to be removed. After releasing the spring compressor, the valve cap, springs and valves can be removed. If the compressor is not available the springs can be compressed by placing a block of wood under the valve heads and using a strip of metal pivoted on one of the rocker pedestal stands. When removing the valves from the head, mark them so they can be replaced into the same guide. When new valves are being fitted this is not necessary of course. Clean off the deposits from the valves and combustion chamber, and clean out the ports. A rotary wire brush in an electric hand drill is a useful tool for this job. Wash all loose dirt from the head so it is nice and clean for examination.

Inspect the valve seats for bad pitting. If the seats are too badly marked, they will have to be cleaned up with a special cutting tool; this is best done by a garage. The valve guides are also best removed and replaced by a garage if they are worn at all. Worn valve guides cause heavy oil consumption and reduce valve life considerably. To check a valve guide, place the valve into the guide so it is about 1/8″ off its seat. Then try rocking it from side to side. There should be no more than .020″ movement. A worn guide can also be detected by looking at the stem of the valve; a dull black deposit of carbon on the stem indicates wear on the guide.

Assuming the valve seats and valve guides are in order, we can start grinding in the valves. This is done by smearing the valve seats with grinding paste. Before putting the valve into the guide, lightly oil the stem. Using the valve grinding stick rotate the valve back and forward using the palms; rotate the valve occasionally allowing the paste to return. While grinding in the valves gradually rotate them so they are seated all the way down. Ensure after grinding in, that all the grinding paste is washed off, as an abrasive will produce wear if left in. Inspection of the seats will show if the valve has been ground in correctly. The seat both on the valve and head should have an even mat grey mark all the way round about 1/10″ wide. Too wide a seat will collect foreign bodies.

(Were there any Mk1s factory fitted with non-six cylinder engines? – Uncle Stan Part)

CRANKSHAFT THRUST WASHERS

ANDY ROBERTS 45/08 April ’89

The manual says that oversize thrust washers were not fitted to the 2500 engine, and therefore some engine reconditioners only supply standard thrust washers. There is no reason why you can’t fit oversize thrust washers to a 2500 engine, and if the end-float is outside limits with the standard washers every reason why you should. Note that the allowable endfloat on the 2000 is 0.006″ to 0.014″, whereas on the 2500 engine it is only 0.006″ to 0.008″. This is what the book says, but I am a bit sceptical! Certainly 2500 engines seem more prone to dropping their thrust washers than 2000’s, but I would not worry until the end float exceeds 0.014″ in either engine. Thrust washers are available 0.0025″ and 0.005″ oversize, which of course reduce the endfloat by 0.005″ or 0.010″ respectively, since there are two of them.

(Ed’s note -You can use a standard one and an oversize one to give endfloat reductions of 0.0025″, 0.005″, 0.075″ or 0.010″!). (Other oversizes are also available – Uncle Stan Part).

Engine – Crankshaft

SUMP REMOVAL

GEOFFREY SHOTTER 16/04 June ’84

Don’t rush out and remove the entire front suspension as some manuals suggest. Merely remove the front crossmember leaving the struts in position, and avoiding the necessity to disconnect the brake-lines. This then becomes a straightforward nut and bolt job. Power steering does add slightly to the work, but air expulsion is very much easier than brake bleeding. Please do change big end bearings at 30,000 mile intervals. It’s only a days’ work and it will pay dividends in crankshaft life. If you do the mains as well, don’t remove them all at once and let the crankshaft drop – it damages the oil seals which then leak profusely and that means another Saturday under the car. (You don’t actually need to remove the cross-member, just undo it and pull it forwards. Disconnect the anti-roll bar, if fitted. – Uncle Stan Part).

TUNING AND IMPROVING THE BIG SIX

MARK UNDERWOOD 12/10 October ’83

Tuning means different things to different people and is therefore a rather difficult subject on which to write. Generally speaking tuning means:
– greater performance with greater efficiency without too much detrimental effect on fuel consumption;
– greater reliability
– greater speed capabilities with an increase in torque
– better handling of the vehicle.

It is pointless to tune any motor car by adding on bits or improving the characteristics of an engine with large increases in horsepower and torque, without improving the handling and braking of the vehicle, without which the full benefit of the extra power cannot be properly utilised, and is therefore wasted. (The post-68 2000 has the same brakes as the 2.5PI – Uncle Stan Part). With the general introduction over, it is absolutely imperative that no penalties whatsoever can be assumed by myself or the Register, nor is it my intention or the Register’s to recommend that any individual owner carry out any modification that would be contrary to the law, i.e. the Road Traffic Acts or Construction and Use Regulations.

Members must also be aware that in any modification of a motor vehicle, certain risks are inevitably involved. Only those who believe they are mechanically competent, with the necessary tooling to undertake the suggested modifications and procedures are advised to do so. This is mainly because neither I nor the Register can assume or accept any responsibility for any damage or injury that may occur as a result of following the procedures and modifications.

It is also imperative that when working with the engine, gearbox, or axle, that absolute cleanliness be observed. Prior to working with these units have them steam cleaned if possible. Ensure that your working surfaces are clean and that you have a plentiful supply of clean rags. For safety’s sake ensure that the working area is well lit and also ensure that you have a plentiful supply of hand cleaner as frequent washing of one’s hands whilst working with oil and grease will leave them not only presentable at the end of the day, but will make handling of awkward items that much easier. It is also a good idea to have a large dust sheet available to cover up the units while you are not working on them.

THE CRANKSHAFT

The crankshaft is one of the weak points in the “Big Six” engine, being only a four main bearing crank and therefore not very well supported. It is therefore limited in its capabilities as to the amount of power it can take. Despite this weakness the crank has proven itself to be very resilient to abuse, and breakages are very rare. The most common problem is that the thrust washers when worn, and sometimes when fairly new, have a nasty habit of dropping into the sump. You may have guessed the end result… not a pretty sight. Manual transmission cars suffer engine “knocking” (bearing wear) within rather low mileages due to continual clutch movements, clutch judder etc, whereas auto transmission cars hardly suffer from this problem until high mileages are encountered, as a result of the transmission, so to speak, being able to soak up violent crank movement.
On removing the crank first visually check for signs of scoring or deep scratches which may make the crank unsuitable. Scratches can be felt by running your nail across the journals. The next step is to measure each of the journals to ascertain that they do not have an out of round condition (in other words not oval) not exceeding 0.0010″, or that they are not flat exceeding 0.0005″. Once checked that the crank falls within these specifications it is than safe to reuse it after it has been crack tested, micro polished and balanced. However, if the unit does not fall within the specifications given (which is normal on a worn engine) proceed as follows:
– have the unit crack tested,
– machine to an appropriate undersize,
– micro polish and balance.

Your local engineering firm will advise you on what other parts are required for them to complete the balancing procedure.

Before assembling crank into block, carefully clean all the oil passages with a small fibre brush, such as a fine rifle bore brush. Use copious quantities of cleaning solvents (paraffin or Gunk) for the initial cleaning, and repeat to finish off with hot soapy water. Blow the crank and its passages dry with compressed air. At this stage DO NOT oil the journals and throws unless you intend to refit the crank into the block immediately. If you do oil the crank, and leave it lying around the oil will merely attract dust and grit and other nasties which can prove extremely harmful. Keep the crank clean and dry until ready for reassembly. Do not wipe the journals with a rag as they leave traces of lint that can enter and foul the lubrication system.

On the assumption that the block is ready to receive the crank, slide new (Vandervell) main bearing shells into position. Lightly oil the shells with a fifty-fifty mixture of good grade oil (GTX) and STP, or alternatively engineers lube, and lower the crank carefully into position.

Next fit the rear crank thrust washers suitably lubricated, followed by the other half of the main bearing shells fitted into the bearing caps. Just before fitting, with a can full of oil, squirt a few shots of oil into each of the oil passages in each journal. Once the caps have been fitted using BRAND NEW bolts, torque down each cap in turn according to the specified torque settings. (New bolts may be required on 2.5 engines, but they are not usually necessary on the shorter stroke, lower stressed 2000 – Uncle Stan Part). After all main bearing caps have been tightened rotate the crankshaft to ensure that it is not binding. Then check crankshaft end float with the use of a dial gauge. Oversize thrust washers are available if the float is found to be excessive (more than 0.010″).

Also essential in a tuned engine is that the crankshaft is hardened after the machining process. This hardening process is essential for long life of the unit (See Stu Harvey’s article 7.2.1, 12/14 – Ed). Either Tuftriding or Nitriding can be used, both having the same end result, with an increase in the wear and fatigue properties of the unit being treated. My own engine had covered 180,000 plus miles on a standard crank so treated without any problems whatsoever. (Nitriding can only be used on EN40B billet cranks. Don’t tuftride new cranks; the residual stress can lead to distortion – Uncle Stan Part).

THE CYLINDER BLOCK

The block is immensely strong and as such does not require any modification. For outright competition high power applications, or for the real enthusiast, it will be necessary to establish zero surface clearance – the distance between the top of the block and the top of the pistons at top dead centre. It is a complicated procedure requiring skill and a lot of patience, with the aid of special gauges. The process is the same whether old or new pistons and con rods are being used, both requiring the engine to be assembled in order to take measurements. Firstly thoroughly clean the top of the block so that every trace of gasket and carbon are removed. Next, mount a dial gauge in such a manner that each piston TDG (top dead centre) can be ascertained, bring No.1 piston to TDG and measure the depth with a depth micrometer between top of piston and top of block. Also measure NO.6 piston at the same time, and record the measurements in tabular form. Rotate the crankshaft to obtain readings for No.2 and No.5, and then No.s 3 and 4. It will now be seen that you have a record of all depths obtained. Again I stress that this operation must be carried out with the engine assembled, using either old or new parts. You cannot take measurements with the old pistons, and then install the new ones, and vice-versa otherwise you will be in a terrible mess. The idea behind all this, as you may have now figured out, is to correct these measurements so that they are all exactly the same, and that all parts will be the same length or height, and takes into account the differences in con rod lengths and piston compression heights (and crankshaft stroke throw – USP) during manufacture. The average clearance on a standard block is around 0.015″ to 0.017″. From the measurements obtained, find the highest value and add 0.005″, and have this resultant figure skimmed off the face of your block. This will ensure that further measuring and machining will not be required at a later stage. Once all machining is completed the block can be taken to bits and faced off.

As far as reboring and fitment of new pistons is concerned, refer to your factory manual for guidance and clearances. On this subject, ask for the bores to be finished off by hand honing with fine stones. If the block is not to be rebored and merely re-ringed, again have the bores honed by hand so that a clearance of 0.004″ to 0.005″ between piston and bore is achieved. This will ensure that any slight tapering of the bores is removed, and it also provides an excellent surface for the bedding-in of the new rings.

CAMSHAFT BEARINGS

Unfortunately in its standard form the block of the 2000 and 2500 does not have removable camshaft bearings. The camshaft itself runs in straight cast iron bores in the block. However it is possible to fit sleeve type bearings of the removable type, although this is really only necessary for real outright power applications. The procedure for fitting these bearings is really quite easy and is not overly expensive. (Necessary for a tuned 2000, if you use more than 6000 rpm with strong valve springs. 1995 cost £200 approx. – Uncle Stan Part). To start with you will need 2 pairs of Triumph Spitfire camshaft bearings (Vandervell part number 142648). These have the same internal diameter as the camshaft journals. The next stage is to take your bare block to the engineers and ask them to line bore the block to the required diameter using the camshaft as a dummy thereby ensuring the correct fitment and clearance after the bearings have been fitted. Don’t forget to fit a new cam core plug at the back of the block, using a good epoxy glue such as Araldite Rapid. We can now consider that all the machining work is complete, and we come to the most important procedure there is when rebuilding an engine – the cleaning procedure. The motto here is to scrub, scrub, and clean, clean until spotlessly clean. To enable this to be carried out with the minimum fuss, remove, and I mean remove, all brackets, oil plugs, all studs, and ancillary equipment. Scrub outside and inside the block faces so that all the oxidised oil deposits and other rubbish are removed, and all faces should end up having a nice dull sheen about them. Again use a rifle bore brush to clean out all the oilways etc. Scrub the bores and oilways with copious amounts of hot soapy water and paraffin so that all swarf, grit, dust, etc. is removed. This is absolutely essential, as if this procedure is not carried out properly it can only mean short engine life, thereby causing extra work in another rebuild, extra expense, and a general drain on your resources. Just be patient and take your time, otherwise you’ll end up in the long term pulling your hair out. All too often I’ve seen some eager beaver just merely wipe down the block, assemble it quickly, and out on the road again, only to find that the nice new engine is back out of the car again in 500 miles. Post mortems have revealed that swarf had not been properly removed. You have been warned …

Reassembly consists of replacing all oil plugs using Loctite Studlock or similar, as this will prevent vibration causing the plugs and studs coming loose in later life. This should only take place after all the oilways have been blown out with compressed air. At th is stage it is a wise move to paint the block with either Hermetite Engine Lacquer or Finnegan’s Smooth rite to the colour of your choice. My personal preference is for about 4 coats of engine lacquer, red at that, resulting in a beautiful finish that is hard wearing and doesn’t fade with the heat produced. Red is chosen quite simply as it shows the slightest trace of oil leak from the engine, and it motivates me to keep it clean. Once the block has been painted, cover it with a cloth and allow the paint to harden for a few days. The airing cupboard is the best place, when the wife is out! If she creates you can always use the excuse that your back has suddenly “gone” and you need a few days rest before removing it.

Follow all the engine reassembly procedures in your manual and you can’t go wrong. Remember, take it easy, don’t rush things, and recheck what you have just done, and you will soon end up with a handsome unit that will give you many thousands of miles trouble free motoring. Good luck …

THE OIL PUMP

I have little to offer on the excellent article written by Chris Witor (1.1.5, 10/17). I’m glad he has done this as it has saved me a lot of time and energy. One vital point to remember is that the oil pump and the oil are the heart and blood of your engine. Any dirt that is picked up by the blood soon finds its way back to the heart with the end result that the pump has a coronary, and bang. If you have not fitted an oil pressure gauge then go out and buy one, and fit it. It is a very useful instrument that can tell you much about the state of your engine and oil. Frequent “reading” will give you ample warning of any impending disaster. (Alternatively, use a 20psi oil pressure warning light switch, instead of the standard one which works at 3 to 5 psi. Use running-in oil if you have fitted new pistons or rings – Uncle Stan Part).

ENGINE MACHINING – PRECAUTIONS

STU HARVEY 10/15 June ’83

Rod Barber, our worthy Chairman (Ed’s Note – and Editor!) has just been obliged to strip his PI engine after only 32,000 miles since a total rebuild. Having examined the main and big end shells I can see an advanced state of wear for such a low mileage. Assuming that the machining and reassembly was correctly carried out – it ran very well and quietly up to a few weeks ago – what exactly happened is a mystery.

The only explanation I can put forward (and have seen like before) is that some residue of “swarf” from the machining process has remained in the oilways of the block (from a rebore) and / or the crankshaft (from a regrind). In my experience some engineers specifically tell you to clean out all the oilways yourself, and some say “nowt” , and some say that the remachined units are ready to be rebuilt. Being a cynic (and a coward) I always thoroughly clean all the oilways and channels etc. I was told once by an engine specialist that the best method is to use a hot water, high pressure jet. If possible I use this but have resorted to garden sprays, bicycle pumps, etc. as available. The main thing is to get all the muck out of the oilways as it is a mixture of emery dust, carborundum grit and particles of the metal removed by the machining process – not the ideal “running in” compound. The hot water for cleaning can be blown out with compressed air or displaced by pumping clean oil through the oilways (an ordinary pressure type oil can will suffice).

While carrying out this operation don’t forget the small holes that feed the rocker shaft. Also remember that the hole is continued up through the cylinder head and any valve lapping paste or grit from valve reseating operations must be removed . This of course may have nothing to do with Rod’s trouble, but it does seem possible that something nasty may have been left behind.

When discussing this aspect of Rod’s engine at a recent Chiltern Group meeting, Chris Witor inspected the bearing shells and whilst agreeing that my theory could be the possible cause, asked why we were using Glacier bearings and not Vandervell, which he reckons are of much better quality and last a lot longer, but do not cost any more. (They do cost more nowadays! – Uncle Stan Part).

By the way, I heartily endorse the advice given in the last issue to replace the oil pressure relief valve plunger and spring periodically. The seating does wear, in which condition it could contribute to “late” oil pressure delivery.