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Sam C

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Hi all

What Triumph Engines and Gearboxes are broadly interchangeable with the standard GT6 engine and box from a mark 3?

The reason that I ask is that a long term plan is to pull the engine out of my GT6 and have it stroked to give 2.5 litres when the gearbox finally gives up and needs to be replaced.

However, on Tuesday I got chatting to a Triumph 2000 owner who seemed to think his engine was identical with mine but fuel injected and 2.5 litres i.e. already stroked.

This has made me think that it may be possible to use a ready built 2.5 litre engine from a different car (up until Tuesday I thought the only ones that had the 2.5 litre engine were TR6s - way too expensive) rather than risk my perfectly good and low mileage engine in the hands of an engine builder.

Many thanks for your thoughts all!

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Any of the 2.5 engines from a saloon or TR will do the job. Some early (TR5 maybe early 6) had a longer tail on the crankshaft so avoid those.
There is a wide variety of cams/compressions etc so do some research, http://www.t2000register.org.uk/ has tech info on the saloon variants.
Or see my ad....

There are some other tings too, the GT6 sump should be used, but needs denting to allow for the longer throw crank near the front (dead easy), carbs, really sprint HS6's bolted to a GT6 manifold, the rest (from memory) comes from the GT6. If you have overdrive you may well find a longer ratio diff is needed, ideally 3.27 but they are a bit weak and rare, or a 3.63 from a spit 1500.


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Late MkIII GT6 blocks should be the same as TR6 & 2.5 Saloons, they commonised the casting. You'll need a 2.5 crank, pistons, (possibly) head depends on the machined depth of the chamber. If you have dome top pistons at present then the head should be ok.

Probably need to change the cam to something a bit lively'er.

and as Clive says the sump and possibly go to a duplex chain, although if you are not going PI simplex should be ok.

When you take the engine apart check for cut-outs in the bottom of the bores. If they are there thats for a 2.5!

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I have a 2.5 in My mk1, wasn't planning on 2.5, but at the time my 2.0L was out for a rebuild, I was offered a very good 2.5 for a very good price!

I love it, but my advice would be go have a drive in something with a 2.5 in it before you decide which route to take!

some ppl prefer the more revvy 2.0L, some prefer the more Torque of the 2.5 !

Roy 8)

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