Triumph 2500PI v TR6

[Steve Trident]

Hi, I have a 2500PI engine and manual gearbox fitted in my Trident. The chassis is modified TR6. The engine number is MG21711HEBW, with a type 516816 head. The car was registered Feb 72 but the engine could be earlier. My question is to what extent are engine and gearbox parts interchangeable with those of a TR6 .
As a second question does anyone know what date my engine number would have been produced.
Thanks

[Yertis]

In your position I'd head to the TR Register forums.

[tapkaJohnD]

Meanwhile, Steve, all the Triumph six cylinder engines were made from the same block design.
The 'small chassis' cars used a different gearbox. Lots of other variations but none major. They'll all fit.

The Saloons mounted the engine canted over to the right, for a lower bonnet line, and so have a different rear engine plate to the TRs, even the 2500Pi. With that exception, which would make for a longer reach for the gear stick if you used a saloon engine and gear box with the OE plate.

John

[Steve Trident]

Thanks to both. Just to clarify: I'm not thinking of changing to a TR6 engine. I need to do some work on my existing engine and while I can get what I need from Moss for TR6 specification I wouldn't know where to go for specifically 2500PI bits.

[caziques]

The basics of all 2.5 engines are the same - block, crank and pistons.

The main significant variation is the camshaft, then there are different head depths (which changes the compression), and late heads have smaller exhaust valves that helps to prevent cracking between the valves.

The most powerful standard cam is the 35-65-65-35 fitted to early TR6 engines. This cam tends to be thirsty when used with carbs.

The best overall cam seems to be the 25-65-65-25, used in MkII Vitesse and early 2.5 PI.

Make sure you use the correct head gasket if rebuilding.

[Yertis]

Caziques, do you happen to know much about the heads fitted to GT6? Specifically the variations in combustion chamber design.

[brrapp]

I can't help with the TR6 specifically but a mate of mine did a straight engine swap from a 2500i to a Vitesse a while ago, all the parts seemed to be pretty interchangeable between all the 6's.

[Dinlowgoon]

caziques said:

The basics of all 2.5 engines are the same - block, crank and pistons.

The main significant variation is the camshaft, then there are different head depths (which changes the compression), and late heads have smaller exhaust valves that helps to prevent cracking between the valves.

The most powerful standard cam is the 35-65-65-35 fitted to early TR6 engines. This cam tends to be thirsty when used with carbs.

The best overall cam seems to be the 25-65-65-25, used in MkII Vitesse and early 2.5 PI.

Make sure you use the correct head gasket if rebuilding.

So if you took a TR6 lump,ditched injection,fitted a 25-65-65-25 cam,this would be the way to go ?
Strombergs seem to be flawed,down to design/parts availability. SU's an alternative ? 1" 3/4's ?
I was also warned off triple 40DCOE's on this setup - any merit in this ? - apart from mpg.(I have a pair on the shelf) Would look awesome of course.
Option 2 (Su's) will most likely be the thinking man's route so i'd better get on Ebay for that 3rd DCOE ... Is there a better cam for the triples ?

[//j17]

Why dump injection?

PI throttle bodies are just that, throttle bodies so rather than dumping them get EFi injector bosses fitted to them and onvert to EFi. More powerful, more reliable and lower fuel consumption.