Club Triumph

Just paid for another load of awesomeness from Wishbone Classics, all Im waiting on now is the flywheel which is due soon.
So now I will have all the parts to get the head done at least, what is the max compression i should shoot for? I will be running new county pistons and the newman 300/280 degree cam. I have heard 10.5:1 a lot but have heard higher in some cases. I plan to megajolt the ignition eventually but would be running on a stock distributor initially.
Cheers

I would say that 10.5 is the highest you should aim for, even with Megajolt. If the timing is slightly out you run the risk of detonation. I'm not sure how high you can safely go with a distributor, bearing in mind that its advance curve probably won't be optimal for your new engine. I remember seeing a Spitfire with a rebuilt high compression engine, that someone naively bolted a standard distributor to. The advance curve was completely wrong for the new motor, and after an hour or so it melted the ring lands due to detonation.

My 2.6 engine is also 10.5-ish, but that's with full EFI and a long duration camshaft (which reduces the dynamic compression ratio). The initial tuning phase will be nerve-wracking!

If you are thinking about fitting Megajolt later, are you going to fit a trigger wheel during the engine rebuild?

I ran just under 10:1 with my PI on the 132 cam and fully electronically managed.

I'd say that represents the limit for 95 octane fuel with that cam as I had more trouble controlling pinking than I've had before or since.  A longer duration cam will reduce the dynamic CR and allow higher static CR.

Vitesse is 10.5:1 (and also fully electronically managed) with the same cam you are getting and that seems good (though more prone to pinking than the old engine which never pinked).  This is a 2L with pop up pistons so will have much more squish than your 2.5 and this more resistant to pinking & det.

Given you run in a hot climate I suggest being conservative......

Nick

I would not go over 10:1 with Triumph Pistons - my mate destroyed a lot of Mazda Pistons ring lands with 11:1 but he always used too much advance with 98 octane and octane booster

I used 10.6 with Mazda Pistons and a maximum of 28 deg total advance - that was fine but only if using 98 octane .
They key to cool running is correct timing - ie not too much or too little and NOT lean especially high up - my PI runs cooler when I thrash it - if the temp climbs markedly when driving hard it's probably lean

Thanks guys. Looks like I'll go for 10.1 then. The dizzy I have has 13 degrees stamped on it, so I think that means 26 degrees crank, and I run no vac advance. The 26 degrees on the dizzy is in addition to the at idle advance am I right?
Feeling the movement in the distributor I have in it now (13 degree) it seems to have much less movement than the simon bbc one I had in it previously- seems like not enough compared to others I have felt, but it seems to move all the way to the stops.
I have read that for a hotter engine you want to go to max advance earlier but not carry as much total advance. Am I on the right track? Also if I set max advance to 28 degrees total, by what revs do I want it to be all in?
As for mixture, I have an afr guage. ATM with the old cam I had it set too rich through the mid range but it always seemed to go leaner up top. What is a good figure to aim for at top end.
Good question about the trigger wheel Nick- I hadn't thought of that. I will get one and fit it to the front pulley before I have the lot re-balanced.

Nick or Andy, could you recommend a good trigger wheel that will fit the Triumph pulley with least modification that you have used?
Cheers

I just had another "you learn something new every day" moment today. I have been cleaning parts and getting the gear box ready, thought Id slip the new clutch release bearing onto the carrier so i could reassemble the box. So when I get the new bearing it's much bigger- o'oh. Then I tried the clutch plate on the gear box spline and yep, too big again. A short net search has revealed that a tr6 and 2500 have different input shafts! Who would have thought, should really be the other way round I reckon. So now Im up for a new plate and release bearing, and hopefully the 2.5 release bearing mates ok with the tr6 clutch cover. Feelin pretty stupid, but still wondering why the difference in the first place- I really thought all these engines were interchangeable.

I always assumed that the TR had the bigger input shafts as they were "manly" cars and should be a challenge to drive, and of course bigger is better.

A 2000 clutch is lighter and in my view better than a TR one.

They use the same cover.

Cheers

Colin

Quoted from josh18

Nick or Andy, could you recommend a good trigger wheel that will fit the Triumph pulley with least modification that you have used?
Cheers

Quoted from thescrapman

They use the same cover.

Cheers

Colin

Quoted from josh18

Nick or Andy, could you recommend a good trigger wheel that will fit the Triumph pulley with least modification that you have used?
Cheers

PI

Nick

My trigger wheel came from Trigger Wheels.com: http://trigger-wheels.com/store/contents/en-uk/d5.html. It's about 130mm diameter, with a small central hole, mounted on an alloy 'fan eliminator' http://www.pattonmachine.com/Fan-Eliminator-Kit.htm

I don't think the trigger wheel will make much difference to the bottom end's balance, it's just easier to fit while the engine is apart.

Thanks guys