Welcome to our resource for MG Car Information.



TR parts and Triumph parts, TR bits, Triumph Car Spares and accessories are available for TR2, TR3, TR3A, TR4, TR4A, TR5, TR6, TR7, TR8, Spitfire and Stag and other TR models are available from British car spares and parts company LBCarCo.

Triumph GT6 - TR6 Block - GT6 Head ?!

I've spent the last year doing a frame-off restore of a Frankenstein GT6 III (KF20068U - mostly) - just getting around to the engine. Here's what I have:

Block CC75244U (74 TR6 ?)
Head 312388
Intake manifold 311749
Carbs ZS no tags - can't identify yet
exhaust aftermarket 3-2-1

If these parts were just slapped together by the DPO without any machining or gasket shimming.... what should I expect regarding compression ratio, high-rev breathing, other wierdness.

Don Gardner

I can't identify the origin of the parts of this bitsa engine from the numbers, perhaps someone can.
But, if you don't know what they are, I suggest it is essential to measure them! The stroke of the block will give away if it was originally 2 litre or 2.5, and the bore if it has been overbored. Measure the volume of the head chambers - whatever it was, you cannot tell if the OP(s) skimmed the head.

A GT6 head on a TR block will give you a CR of about 10.5, the max on 95octane fuel without risk of pre-ignition. If the head has been skimmed to raise the CR, acceptably on a 2 litre GT6, you could be in trouble with a 2.5 TR block.

Good luck.
PS Does DPO stand for d*mn*d PO?

(That's the name I've been assigned...)

I'm pretty sure the block is 2.5 TR from 73 or 74 probably 8.? fairly low compression. The intake manifold is GT style and the similar part number to the head makes me think that they are both GT6 - maybe even from the original engine. Speculating that somebody threw a rod and swapped out the short block with something he thought was the same.

What kind of compression guage reading would I get if I had 10.5 compression?

Yup. That's what the D is. You shoulda seen.... well anyway. Wait til they see what I did.

This thread was discussed between 13/03/2002 and 14/03/2002

Triumph GT6 index