M 2500 (TR6) Engine - help please
Discussion
Just picked up my 2500, which I knew needed some sorting when I agreed to buy it (hought I'd done my homework but now I have lots of questions) help advice on the following much appreciated:
Knocking - fine when it starts but after it warms up a bit it starts to knock, sounds like big end. I've been told the new bearings you can buy aren't up to much - is this correct? where should I shop for them?
Oil pressure - what should it be? On start up it seems OK with the gauge moving to middle-ish, as it warms up, pressure drops off (knocking starts) and it settles just off the bottom, bearly moving when rev'd. Could the oil pump be the source of the problems, or is it just a symptom of the big end prob'?
Carburation - its had a couple of 2" SU's fitted - anyone else ever come across this set up, any advice on setting up?
Engine general - Was the engine the same standard as the export model TR6 (minus the emissions gubbins), ie: same cam, compression, etc? With a view to going hunting for some extra power in the future, is there anyone in TVR land who could rebuild / prepare one of these engines, or do I need to cross over into Triumph land?
Cheers...
Knocking - fine when it starts but after it warms up a bit it starts to knock, sounds like big end. I've been told the new bearings you can buy aren't up to much - is this correct? where should I shop for them?
Oil pressure - what should it be? On start up it seems OK with the gauge moving to middle-ish, as it warms up, pressure drops off (knocking starts) and it settles just off the bottom, bearly moving when rev'd. Could the oil pump be the source of the problems, or is it just a symptom of the big end prob'?
Carburation - its had a couple of 2" SU's fitted - anyone else ever come across this set up, any advice on setting up?
Engine general - Was the engine the same standard as the export model TR6 (minus the emissions gubbins), ie: same cam, compression, etc? With a view to going hunting for some extra power in the future, is there anyone in TVR land who could rebuild / prepare one of these engines, or do I need to cross over into Triumph land?
Cheers...
Vague memory of 25Lb @ idle (hot), & 60 @ redline, or was it 80? Knock may mean crank machining. I'll try to remember to look up the spec for where oil press relief valve opens, later today.
For great power/reliability, in this country, there are two people I would go to. Their names are Glen Effinger, and J.K. Jackson. They're the only two. Suggest you find their UK equivalent. Maybe you can wait until Jelly stops monopolizing his father's time.
B.
For great power/reliability, in this country, there are two people I would go to. Their names are Glen Effinger, and J.K. Jackson. They're the only two. Suggest you find their UK equivalent. Maybe you can wait until Jelly stops monopolizing his father's time.
B.
Push your crank back and forth when the engine is stopped see if you can get any discernable movement. The triumph 6 has a thrust washer at the front of one of the crank journals which is known to migrate around the crank then when it is upside down drop into the sump giving a thrust and rumble not unlike big end failure. Apart from this well known achilles heel the engine is pretty bullet proof.
the fixes are also well known in triumph circles.
N.
the fixes are also well known in triumph circles.
N.
Go straight to Triumph world on this one - there's loads of information out there. My personal suggestion would be to contact Chris Wittor who will give you a good steer on the best set up and bearings available.
Vandervelle were always the first choice, but are thin on the ground now, Chris will give good advice on options.
http://www.chriswitor.com/
Vandervelle were always the first choice, but are thin on the ground now, Chris will give good advice on options.
http://www.chriswitor.com/
As we've discussed here before, there's also a nice triple carb set up available from Good Parts, in the US. Richard does some lovely things, truly. Still, to get real life out of the engine, go to a racer. You haven't lived until you've heard J.K. Jackson's 2.5 exceed 8,000RPM. The tonal quality changes from a scream to a howl. Beautiful, sexy, mad, and frightening, all at the same time.
Sorry I couldn't dig up a better clip of it.
B.
Sorry I couldn't dig up a better clip of it.
B.
The 2.5 engine has very poor crank harmonics, getting one to rev reliably and regularly to 6500 rpm is a challenge, let alone 8000! Like most things, it can be done, but only if you are prepared to throw and awful lot of money at it - think bespoke crank for a start.
I would recommend concentrating on torque improvements at realistic engine speeds. There are plenty of gains to be had from improvements to induction and exhaust. There is also quite a difference in how theTriumph heads flow, the best one being the late head from the 2500S saloon. If you really want to make it rev then you are better off using the 2000 crank which is far better balanced and will rev reliably. You can just about get another 200cc out of the bore making either a 2.2 or 2.7 depending on the crank you choose. Common conversions use Mazda pistons iirc.
I would recommend concentrating on torque improvements at realistic engine speeds. There are plenty of gains to be had from improvements to induction and exhaust. There is also quite a difference in how theTriumph heads flow, the best one being the late head from the 2500S saloon. If you really want to make it rev then you are better off using the 2000 crank which is far better balanced and will rev reliably. You can just about get another 200cc out of the bore making either a 2.2 or 2.7 depending on the crank you choose. Common conversions use Mazda pistons iirc.
It's unlightly that the car will still have the original low compression,FED spec head, which was 0.100" thicher than the Pi heads. The ports in the FED spec are cast slightly different, meaning it's not just a case of machining it down.
I've got the exact same big end knock in my 2500M. I'm going to change the big ends next month when the tax runs out. The big worry is that if you leave it to long the bearings spin in the con rod. If it is the thrust washer thats dropped out or has excess play, you can simply refit a new one (they come in various thicknesses) to achive the correct float. The best fix is to machine and fit a moded, pinned thrust washer, but the engine will have to come out to do that.
Has the car got a spin on filter adapter? If it hasn't fitting one might help with the Triumph straight 6 start up death rattle. The spin on filter(short) will have to sit at 45 degrees, due to the chassis rail on the M's getting in the way.
I've got the exact same big end knock in my 2500M. I'm going to change the big ends next month when the tax runs out. The big worry is that if you leave it to long the bearings spin in the con rod. If it is the thrust washer thats dropped out or has excess play, you can simply refit a new one (they come in various thicknesses) to achive the correct float. The best fix is to machine and fit a moded, pinned thrust washer, but the engine will have to come out to do that.
Has the car got a spin on filter adapter? If it hasn't fitting one might help with the Triumph straight 6 start up death rattle. The spin on filter(short) will have to sit at 45 degrees, due to the chassis rail on the M's getting in the way.
Edited by eric0 on Thursday 1st September 10:25
Edited by eric0 on Thursday 1st September 11:17
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