how come I've run a big end? Again?
Discussion
Here's the story:
Competition Midget 1500 (ie Triumph engine). I know this engine has a poor reputation (and I don't need a lecture about it!) but lots of people run Spitfires and Midgets with the same sort of power as mine (less than 75bhp at the wheels) without problem.
Following a holed piston, the bottom end was rebuilt by local Triumph specialist and was fitted by local garage. The crank was ground and balanced by a local firm, used regularly by the specialist and race teams. Oil cooler was replaced. Expensive Penrite oil of correct grade used. I then competed in a rally and on return had run a big end (they were scored when removed but I’ve seen worse). By this time I probably had covered less than a thousand miles since the rebuild with less than 500 before the start of the event and several minutes at competition speeds some of which where the engine was badly misfiring.
I could think of lots of possible explanations for the failure and the big ends were replaced by my local garage with heavy duty King bearings.
Since then I have done a couple of thousand miles including several events, including Goodwood sprint which is tough on cars with about 200 seconds almost entirely foot to the floor (and probably 20 seconds with the rev counter nudging red, flat in forth). The car got very hot at Goodwood.
About 100 miles after Goodwood I did some work on a cooling system. By the end of a 100 mile test drive I am in no doubt that I have run a big end.
Specialist has built countless of these engines before and has a good reputation. Local garage a good man and conscientious.
I could replace the big ends, run it in super carefully and hope for the best but, since this will be the second set in about 1500 miles I wonder if there any checks I can do? Ideally ones that I can do from underneath without stripping the engine? Also I could fit expensive ARP bolts in an effort to stiffen it up. Or I could start again - I've got an offer of a new crank from the specialist.
Thanks (and sorry for the essay!)
Competition Midget 1500 (ie Triumph engine). I know this engine has a poor reputation (and I don't need a lecture about it!) but lots of people run Spitfires and Midgets with the same sort of power as mine (less than 75bhp at the wheels) without problem.
Following a holed piston, the bottom end was rebuilt by local Triumph specialist and was fitted by local garage. The crank was ground and balanced by a local firm, used regularly by the specialist and race teams. Oil cooler was replaced. Expensive Penrite oil of correct grade used. I then competed in a rally and on return had run a big end (they were scored when removed but I’ve seen worse). By this time I probably had covered less than a thousand miles since the rebuild with less than 500 before the start of the event and several minutes at competition speeds some of which where the engine was badly misfiring.
I could think of lots of possible explanations for the failure and the big ends were replaced by my local garage with heavy duty King bearings.
Since then I have done a couple of thousand miles including several events, including Goodwood sprint which is tough on cars with about 200 seconds almost entirely foot to the floor (and probably 20 seconds with the rev counter nudging red, flat in forth). The car got very hot at Goodwood.
About 100 miles after Goodwood I did some work on a cooling system. By the end of a 100 mile test drive I am in no doubt that I have run a big end.
Specialist has built countless of these engines before and has a good reputation. Local garage a good man and conscientious.
I could replace the big ends, run it in super carefully and hope for the best but, since this will be the second set in about 1500 miles I wonder if there any checks I can do? Ideally ones that I can do from underneath without stripping the engine? Also I could fit expensive ARP bolts in an effort to stiffen it up. Or I could start again - I've got an offer of a new crank from the specialist.
Thanks (and sorry for the essay!)
Edited by BMWChris on Monday 16th August 17:42
cptsideways said:
Have you an oil pressure gauge? if so what does it say when your cornering or braking?
Yes you may have a windage tray but that doesnt mean you always have oil pressure
Pressure seems to stay constant at around 60 psi hot as soon as you've got a few revs on, 20 at tickover.Yes you may have a windage tray but that doesnt mean you always have oil pressure
Pump was replaced as part of rebuild and I replaced pressure gauge recently so it should be accurate but its not one of those ones that goes up and down like a rev counter so it might not show a drop for a second or two. On the sweeping bends at Goodwood I was watching the gauge (with foot hovering over clutch) and it didn't seem to drop.
Chris,
Not sure if you have a copy of "British Leyland Competition Preparation Manual 5th Edition " for the Triumph 1500.
Apparently the 1500 was used to test bearings and is known to hammer them - not sure if this is fact or legend.
Section 1 Page 42 says ....."The oil feed holes to the end main bearingsare kept stock, but since the centre main hole feeds two rodsit is drilled out to 5/16". Drill out the oil feed hole from the gallery (behind the 1/8" pipe plug) to 5/16"and remove all fazes from the intersections of the oild holes.
Note The distributor locating sleeve has to be removed to gain access from the main oil gallery drilling to the centre main bearing"
Section 2 - Use stock factory main bearings with .0025" clearance and "Clevite 77" MGB rod bearings (Part No CB792P in .010" undersize. File the outside edge of the locating tang on the bearings to fit the bearings to the rods. Even though the bearings are quite a bit wider than stock they only need chamfering to fit. Grind the crankshaft to 1.8665" (about .009") to get the recommended .002" clearance.
Section 3 - Make the sump deeper by 1" - my words but the book has 2 pages and pictures of the sump and the oil pickup etc
If you PM me I'll get you a copy of some pages
Not sure if this is linked to the problem you have but it does look like work is needed ...
Chris
Not sure if you have a copy of "British Leyland Competition Preparation Manual 5th Edition " for the Triumph 1500.
Apparently the 1500 was used to test bearings and is known to hammer them - not sure if this is fact or legend.
Section 1 Page 42 says ....."The oil feed holes to the end main bearingsare kept stock, but since the centre main hole feeds two rodsit is drilled out to 5/16". Drill out the oil feed hole from the gallery (behind the 1/8" pipe plug) to 5/16"and remove all fazes from the intersections of the oild holes.
Note The distributor locating sleeve has to be removed to gain access from the main oil gallery drilling to the centre main bearing"
Section 2 - Use stock factory main bearings with .0025" clearance and "Clevite 77" MGB rod bearings (Part No CB792P in .010" undersize. File the outside edge of the locating tang on the bearings to fit the bearings to the rods. Even though the bearings are quite a bit wider than stock they only need chamfering to fit. Grind the crankshaft to 1.8665" (about .009") to get the recommended .002" clearance.
Section 3 - Make the sump deeper by 1" - my words but the book has 2 pages and pictures of the sump and the oil pickup etc
If you PM me I'll get you a copy of some pages
Not sure if this is linked to the problem you have but it does look like work is needed ...
Chris
Electron said:
Chris,
Not sure if you have a copy of "British Leyland Competition Preparation Manual 5th Edition " for the Triumph 1500.
Apparently the 1500 was used to test bearings and is known to hammer them - not sure if this is fact or legend.
Section 1 Page 42 says ....."The oil feed holes to the end main bearingsare kept stock, but since the centre main hole feeds two rodsit is drilled out to 5/16". Drill out the oil feed hole from the gallery (behind the 1/8" pipe plug) to 5/16"and remove all fazes from the intersections of the oild holes.
Note The distributor locating sleeve has to be removed to gain access from the main oil gallery drilling to the centre main bearing"
Section 2 - Use stock factory main bearings with .0025" clearance and "Clevite 77" MGB rod bearings (Part No CB792P in .010" undersize. File the outside edge of the locating tang on the bearings to fit the bearings to the rods. Even though the bearings are quite a bit wider than stock they only need chamfering to fit. Grind the crankshaft to 1.8665" (about .009") to get the recommended .002" clearance.
Section 3 - Make the sump deeper by 1" - my words but the book has 2 pages and pictures of the sump and the oil pickup etc
If you PM me I'll get you a copy of some pages
Not sure if this is linked to the problem you have but it does look like work is needed ...
Chris
Hi Chris,Not sure if you have a copy of "British Leyland Competition Preparation Manual 5th Edition " for the Triumph 1500.
Apparently the 1500 was used to test bearings and is known to hammer them - not sure if this is fact or legend.
Section 1 Page 42 says ....."The oil feed holes to the end main bearingsare kept stock, but since the centre main hole feeds two rodsit is drilled out to 5/16". Drill out the oil feed hole from the gallery (behind the 1/8" pipe plug) to 5/16"and remove all fazes from the intersections of the oild holes.
Note The distributor locating sleeve has to be removed to gain access from the main oil gallery drilling to the centre main bearing"
Section 2 - Use stock factory main bearings with .0025" clearance and "Clevite 77" MGB rod bearings (Part No CB792P in .010" undersize. File the outside edge of the locating tang on the bearings to fit the bearings to the rods. Even though the bearings are quite a bit wider than stock they only need chamfering to fit. Grind the crankshaft to 1.8665" (about .009") to get the recommended .002" clearance.
Section 3 - Make the sump deeper by 1" - my words but the book has 2 pages and pictures of the sump and the oil pickup etc
If you PM me I'll get you a copy of some pages
Not sure if this is linked to the problem you have but it does look like work is needed ...
Chris
I'd never heard of the Competition Preparation Manual for the 1500. I'll PM you as it would be interesting to read. I wonder if I could get a complete one from somewhere?
I had been told (on here) about the enlarging main bearing oil bit but had shyed away from it becuase a) I was told it wasn't needed for what I was going to do and b) it seemed to me that the opportunity to cock it up would be substantial! However, do you think it would impact the big ends as these, rather than the mains are the problem.
Regarding the MGB big ends - I was hoping that the heavy duty King bearings would be as tough.
davepoth said:
The 1500 engine is very hard on bearings. It's a stroked 1300, so it's very undersquare at 2.9" bore to 3.44" stroke. That's very hard on the crank, which whips about at high revs. Can I ask if the crank has been ground or not? I'd want as much meat on the crank as possible.
Crank has been ground. I think only once. Thanks for all the replies so far guys.
Chris
A bit more background on the topic and detail on your King bearings ...
In 1968 Triumph became part of BLMC who were intent on cost saving such that in 1970 a major revision was made to the engine with the release of the Spitfire MkIV. It is this revision that would become the Achilles Heel of the later engines. The change centred primarily around the crankshaft. In order to rationalise machining operations the journal diameters were increased to the same size as those on the 6-cylinder engine (as fitted to the Vitesse, GT6 and TR5/6). Journal diameters increased from 2.0005” - 2.0010” to 2.3115” - 2.2120” (main bearing journals) and from 1.625” - 1.6255” to 1.875” - 1.8755” (crankpin journals). In doing so this made the crankshaft heavier with larger diameter but narrower bearings. Thus the later 1296cc crankshafts have more bearing drag than the early ‘small bearing’ cranks and, with the increased weight, take more power to accelerate.
Unfortunately BLMC compounded this by downgrading the steel used for the crank from EN40B to the far inferior EN16U. Given that the engine is a 3-main bearing design, the use of a heavier crank in an inferior material means that crankshaft flex starts to become a problem, hence the late 1296cc and all 1493cc engines are referred to as ‘floppy crank motors’. At some stage in the design of the engine (from 1296cc engine number FH25001E and all 1493cc engines) the cylinder bores were also recessed which was said to improve the sealing of the cylinder head gasket (even though earlier units had not had a problem). This would limit the safe over boring of the engine to a mere 20thou and, in fact, can cause problems with detonation in tuned motors. If overboring greater than 20thou I deck the block flat and use the earlier 1296cc head gasket. Doing this will also mean that the pistons will need to be decked so as to give 20 – 25 thou clearance beneath the head gasket.
In 1972 the engine was again increased in size by stroking it to 87.5mm giving 1493cc. By this stage the engine really was at the limit of what could be done to it and the fact that it had a ‘floppy’ crank coupled with such a long stroke meant that failures would be commonplace unless certain aspects of the design are addressed. Fundamentally, for the reasons discussed earlier, crankshaft flex on the 1493cc motor is a major concern since it can rapidly lead to the oil overheating causing oil film breakdown with concomitant damage. Given that the motor is a 3-main bearing design, aside from the stroked crankshaft being poorly supported, it is the centre main bearing that feeds numbers 2 and 3 big ends. Any form of oil film breakdown will rapidly lead to wear of these bearings and, if not caught soon enough, a connecting rod (usually number 3) making a bid for freedom at high speed through the side of the crankcase. This is one of the reasons why the 1493cc unit cannot be revved like its smaller brethren.
However these failings can be addressed so as to produce a reliable unit with longevity between rebuilds. Primarily it is the oil system that should be sorted out, since this is at the heart of the problems. Fundamentally it is high oil temperature leading to oil film breakdown that kills Triumph 1500 engines. For this reason it is ESSENTIAL that an oil cooler be fitted; a 13 row by 235mm cooler is perfectly adequate (although for 'hard' use a 16 row is better). This is especially the case with the 1500 Midget, since it has the lowest overall Factory gearing of cars fitted with this power unit, as well as an engine bay that runs far hotter than (say) the equivalent Spitfire.
In terms of the oil being used you MUST use a good 20/50 (with ZDDP to prevent tappet wear) and change it yearly or every 6000 miles (whichever comes first), my personal choice is for Valvoline VR1 20/50 Racing. If the engine is in any state of tune (Stage one upwards) then use a 20/60 such as Penrite HPR 30.
Having sorted the oil and oil cooling, then modifications can be made to the oil system to increase its efficiency. Firstly it is essential to use the later type oil pump. This has an angled pick up that sits lower in the sump and better resists oil surge (if surge becomes a problem such as on Track Days then a single longitudinal baffle can be brazed into the sump, or better still a 'Windage Tray'). Additionally care should be taken to reduce the endfloat on the pump to the minimum quoted figures:
Inner Rotor endfloat – 0.0004”
Outer Rotor endfloat – 0.0004”
Rotor Lobe clearance – 0.010”
Outer Rotor-to-Body clearance 0.008”
Given that the centre main bearing feeds numbers 2 and 3 big ends, then an increase in flow to here is beneficial. The gallery can be opened out to 5/16” (7.9mm), to do this requires the removal of the distributor driveshaft bush and care should be taken upon reassembly to attain the correct distributor endfloat.
While the crankshaft is not particularly well supported, the use of main cap straps or even steel main caps is not required on a road going motor. What should be done however, is to bottom tap the main bolt holes and fit longer high tensile bolts (3.25” UHL), my preference being for socket headed bolts (with case hardened washers) which can be wire locked in place (in addition to using loctite). At the same time as addressing the mains, the big ends should be fitted with high tensile bolts (the originals should NEVER be re-used). Given the amount of 'monkey metal' fasteners being supplied these days, I suggest you use ARP bolts (which are stronger than the con rods) – a bit of a 'no brainer' really. Alternatively (for those in the UK) Ford Sierra Cosworth big end bolts can be used since they are a straight swap (and somewhat cheaper!). Similarly I use ARP head studs and flywheel bolts.
The crankshaft / flywheel / front pulley / clutch MUST be accurately balanced to help cut down on vibrations inducing crank flex (the stock factory balance is poor at best and is, I believe, a factor in shortening the life of the engine); a lightened flywheel is also of help here. Additionally I lighten the rods by polishing them down the beam (as well as removing the 'cup' at the little end). I then balance them end-to-end and overall to within 0.1g. If you are worried about con rod strength and unwilling to shell out ££££ on H-Section forged rods (qv later) then use the early TR5 rods since they are basically the same albeit stronger and lack the hole in the shank above the big end.
With respect to bearings, ideally a lead-indium type should be used since these will better resist the loads encountered than will reticular tin ones. Unfortunately Vandervell VP2 are no longer available for this engine. This leads us to some choices:
For 'hard' use it is possible to fit MGB big end bearings (original part no. AEB4512) at 0.010” undersize (for a standard crank). The crankshaft should be ground to 1.8665” – 1.867" (ie 8.5 thou). The outsize edge of the locating tang on the bearings needs to be filed down slightly to locate them correctly in the con rods. Additionally, since these bearings are wider than the originals, the fillet radius of the journals must be checked after grinding and modified as necessary.
Having done this, while Tri-Metal VP2 bearings are unavailable, the alternatives are:
AE GS2541LC, which is a Tri-Metal, sintered lead-copper bearing. This is essentially the same bearing as the Glacier Vandervell VPR91173LC but which uses a lead/tin/copper overlay as opposed to the lead indium in the old VP2 compound.
This is a high quality bearing piece able to withstand moderate to high loads
A better alternative is the Clevite 77 compound (part no. CB792P), which is made in the USA. This is another Tri-Metal design using a lead/tin/copper overlay, the difference being that it uses a cast copper/lead material (similar to the old VP2) and, hence, is about 20% - 30% tougher in its ability to withstand loads than is the GS2541LC.
A final alternative is to use ACL Duraglide 780 Tri-Metal heavy duty bearings (part no. 4B2250). These are essentially similar to the Clevite design.
If you don’t wish to go to the effort of fitting MGB bearings, and for a car that will see only normal / occasional track day use the expense is probably not worthwhile, then 'normal' Tri-Metal bearings to fit the big ends are available from King (part no. CR4403AM).
With regards to the main bearings having a VP2 like compound isn’t as critical however I still believe the best bearings available should be fitted. To this end I would suggest using King part no. MB341AM.
With regards to bearings made by King, while they are available from the manufacturer in sizes up to +60 thou in the USA, for those of us in the UK the sole supplier is 'County' under the brand name 'County Heavy Duty'; while the parts come in boxes marked 'King' they are actually stamped 'County'. Furthermore County have cornered the supply of these bearings and (for some unfathomable reason) do not supply in sizes greater than +20 thou.
Another worthwhile modification is to source an earlier style 'small bearing engine' camshaft and insert cam bearings into the block since in the 1493cc motor the cam runs direct in the block with no bearings.
These engines can also suffer oil feed problems to the rocker gear (although this is more the case on the earlier 1147cc motors) and there are a number of companies that will sell you an external rocker feed kit. Unfortunately ALL these kits are fundamentally flawed as they come, and lack adequate instructions as to their fitting.
EVERY kit I have seen uses a –3 hose with a banjo fitting to go into the oil gallery plug at the back of the head, and a 3/8" UNF female fitting that attaches to an adapter block that has a 1/8 NPTF male thread that screws into the main oil gallery beneath the distributor (the adapter block is there so that the oil pressure gauge line / pressure transmitter can be retained). A moment’s thought, given what I have said about oil feed to the centre main bearing, will show up just why this is a BAD idea. By connecting the rocker feed in this way you will INEVITABLY rob oil from the centre main, hence you will actually make your motor more likely to go pop! Additionally, with no restrictor, you will over-feed oil to the rockers causing problems with inlet valve stem oiling at low rpm (meaning your motor will both burn oil and be closer to causing detonation from the reduction in octane of the fuel/air charge!). Finally, merely fitting an external oil feed while the internal oilway to the cylinder head is active will cause cavitation in the oil galleries and all sorts of flow problems.
By far the best way to fit an external rocker feed is to firstly block off the vertical oilways in the block and head (use a tap and an 8mm grub screw in both block and head) and to take the feed from the main gallery at the rear of the block (opposite number 3 main) via the 5/16” UNF oilway plug tapping. To do this you will need a –2 to –3 male-male adapter to screw into the side of the block (the fact that this tapping is -2 means that you do not need a further restrictor).
Another problem often reported with the Triumph 4-pot is the tendency for the thrust washers to drop out on high mileage engines. This will rapidly result in wear to the sides of number 3 main bearing cap and a block and crank that are scrap. While you could silver pin the thrusts in place, this is really only of use on a race engine that undergoes routine teardowns and rebuilds since wear of the thrusts will mean the heads of the silver pins becoming proud and damaging the crank. For a road / occasional Track Day motor I wouldn’t bother, just check the thrusts every 40,000 miles or so.
With regards to forged cranks and con-rods:
Farndon engineering in the UK http://www.farndon.com/index.htm have supplied Triumph 1500 cranks in EN40B but the cost is horrendous (around 2-3000 GBP) and IMO too expensive for a road engine.
Additionally Carillo will supply forged H-Section con rods (at around 1000 GBP), but again these are pointless on a road engine. The reason being that a road going motor will never see the sort of rpm that requires such. The stock rods are good enough for power outputs upto around 120bhp, but in order to get this sort of figure you'd have a car that would be virtually undriveable on the street. Additionally you still run into the problems with the narrow big end bearings so you'd still have to go down the MGB route.
There's some really useful and interesting info from Electron, however, I can't help thinking that the OPs problem is simpler than this. A 1500 making less than 100 bhp simply shouldn't knock out big ends within 1500 miles unless something is fundamentally wrong with the build.
I am not a fan of County bearings and would make efforts to source some proper Vandervell ones from an Autojumble as there are still some originals about. Above all though, I'd be checking both the quality of the machining on the crank and that the rods are both straight and that the big end is still within tolerance for ovality.
The 1500 isn't a great base for a high stress application, but a properly built standard bottom end shouldn't fail as quickly as this one has.
I am not a fan of County bearings and would make efforts to source some proper Vandervell ones from an Autojumble as there are still some originals about. Above all though, I'd be checking both the quality of the machining on the crank and that the rods are both straight and that the big end is still within tolerance for ovality.
The 1500 isn't a great base for a high stress application, but a properly built standard bottom end shouldn't fail as quickly as this one has.
Good point - also perhaps a small wooden block behind the accelerator pedal for sprints ..
I really don't think these engines like to be thrashed ...
The background to my posts
We run an 1147cc six port Triumph engine in the Electron Minor.
Previously it kept being sick on the startline at Gurston Down after a couple of runs .. we tried to stick to 5k rpm but each run the temptation to give it more beans probably got the better of us.
We had problems with crank thrust washers failing ... front timing plate leaking oil and overheating ... but the 1147cc is a bit tougher than the 1500.
We kept pulling it apart like Chris and had similar but different issues.
Finally I dug deep and got Cambridge Motorsport to build a proper engine with everything balanced straightened line bored decent bearings etc big bill but we've had nothing but fun ever since ...
I think I've emailed Chris before about being careful which Triumph racing engine supposed 'specialist' you use from my costly and bitter experience
Plus another TR3a I know could not even start a tour after having costly engine work done at another reputed racing engine specialist
With with the TR3a it might have been one-off poor work I know that at least one other can keep in business and keep a good reputation with some wilst others (not just bitter me) know better
So be careful where you go and do a lot more and deeper research than you should need to do
Having said that it seems like Cambridge Motorsport might be a good place to go to
Plus another TR3a I know could not even start a tour after having costly engine work done at another reputed racing engine specialist
With with the TR3a it might have been one-off poor work I know that at least one other can keep in business and keep a good reputation with some wilst others (not just bitter me) know better
So be careful where you go and do a lot more and deeper research than you should need to do
Having said that it seems like Cambridge Motorsport might be a good place to go to
There must be a fundamental flaw but it could be as simple as something having got into the engine during the build (which took place in 3 locations) - the first set of bearings were scored, which might support this. I'm thinking of using a flushing oil and sticking a new set of shells in and seeing what happens. I might try and measure the crank to make sure it hasn't been ground undersize or oval but I'm not sure how accurate this will be working from underneath with the engine in the car. If it works then cool. If it doesn't I'll have to re think over the winter.
Ok, how about this for a plan (assuming damage is being caused by bits in the engine).
1) Run up to temp (despite run big end - it only knocks at certain revs / loads)
2) Drain oil
3) Refill with new oil and replace filter (not sure about type of oil to use - expensive to protect rest of engine, cheap as will be disgarded, flushing)
4) Run up to temp again, drain and disgard oil
5) Remove sump and clean, remove oil pump and clean inside, remove oil pump lines and clean inside (not sure how to do this - bottle brush?), try to flush oil cooler (again, not sure if this is possible)
6) Replace shells, reassemble, refill oil
7) Run in REALLY gently.
What do you think?
1) Run up to temp (despite run big end - it only knocks at certain revs / loads)
2) Drain oil
3) Refill with new oil and replace filter (not sure about type of oil to use - expensive to protect rest of engine, cheap as will be disgarded, flushing)
4) Run up to temp again, drain and disgard oil
5) Remove sump and clean, remove oil pump and clean inside, remove oil pump lines and clean inside (not sure how to do this - bottle brush?), try to flush oil cooler (again, not sure if this is possible)
6) Replace shells, reassemble, refill oil
7) Run in REALLY gently.
What do you think?
BMWChris said:
Ok, how about this for a plan (assuming damage is being caused by bits in the engine).
1) Run up to temp (despite run big end - it only knocks at certain revs / loads)
2) Drain oil
3) Refill with new oil and replace filter (not sure about type of oil to use - expensive to protect rest of engine, cheap as will be disgarded, flushing)
4) Run up to temp again, drain and disgard oil
5) Remove sump and clean, remove oil pump and clean inside, remove oil pump lines and clean inside (not sure how to do this - bottle brush?), try to flush oil cooler (again, not sure if this is possible)
6) Replace shells, reassemble, refill oil
7) Run in REALLY gently.
What do you think?
Chris, given how easy it is to change the big end shells in situ in a spitty, it can't do any harm to try. However, I would definitely try to get a vernier on the crank to see what it's like and pull the pistons right down in the bores, torque the big end caps on the rods and measure the bearing housings. If they are wrong you'll never get the engine to stay together.1) Run up to temp (despite run big end - it only knocks at certain revs / loads)
2) Drain oil
3) Refill with new oil and replace filter (not sure about type of oil to use - expensive to protect rest of engine, cheap as will be disgarded, flushing)
4) Run up to temp again, drain and disgard oil
5) Remove sump and clean, remove oil pump and clean inside, remove oil pump lines and clean inside (not sure how to do this - bottle brush?), try to flush oil cooler (again, not sure if this is possible)
6) Replace shells, reassemble, refill oil
7) Run in REALLY gently.
What do you think?
You can buy flushing oil which should help and, if you remove the oil cooler, you should be able to back flush it. It's not a terribly exact science as the cooling fins will tend to hold debris, therefore, if you think that you've got hard debris in there (rather than just white metal off the shells) then your only option is to replace it.
A properly prepared crank shouldn't need much running in.
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