View Full Version : TR6 TR6 engines

03-29-2006, 07:02 PM
I have a 69 TR6. I wanted to get a spare engine and transmission so that I don't have as much down time the next time. I found a guy who will sell me his spare 74 engine and transmission (He sold his TR6 a while ago and is selling off his extra parts.) Would I have any problems using these in my 69? Thanks, Kevin

03-29-2006, 07:18 PM
I'll let the real TR6 experts really give you the correct info, but here's some quick thoughts from a former 69 and 74 TR6 owner: the 69 has a high compression engine vs the 74 which is low compression - the heads are different, I think different enough that intakes will not interchange. The 69 will have a single downpipe exhaust, I think the 74 had double downpipe, but that may be less a problem. I think otherwise it can be a pretty simple bolt in exchange - possibly with some mods to the rear tranny mount.

03-29-2006, 07:24 PM
The only problems that come to mind are the different head configuration and pulley sizes.
The head intake and exhaust ports are different. Your current manifolds will bolt right up but won't allow for proper air flow. The engine will still run, but you will most likely suffer some in performance.
The early engines also had 3/8 inch belts where the later cars had 1/2 inch fan belts. You may have to swap pulleys on the engine and the alternator to avoid belt wear problems. Changing the alternator pulley would be easier than changing the alternator itself since then you would have to alter the wiring harness to match the receptacles.
If these obstacles concern you, look for a '69-'71 engine.

03-29-2006, 07:26 PM
I've heard of spare coils, spare points and condensors, spare tires, even spare distributors. But spare engines. I kinda think that is a stetch. As the above post so aptly points out, there is a lot more to bite off than you might be willing to chew. Just me.


03-29-2006, 08:08 PM
If your going to rebuild the 74 engine for a later swap , you can mill & port the later head to increase perfomance to even better than pre-emmision performance.
One other difference would be the transmission mounting. I'm not sure about the posibility of ballasted versus unballasted ignitions.

03-29-2006, 08:59 PM
O.K. Go for it, I just did the same thing --I rebuilt my spare late model motor to go in my 71. If you use your early model head--use early model intake manifold , late model head use late model intake(early or late exhaust manifold will fit either one). With the late model block use late model crank pulley, alternator pulley, water pump. The late model engine has a different crankshaft and you must use the late model flyweel. A late model block takes a late model head gasket, just order a late model gasket kit. There is nothing wrong with a spare motor, mine came out of my parts car that had been used for my 71 restoration.

03-30-2006, 10:42 AM
Thanks for all the input. I admit that I am confused about some of the information, but based on all the input, I am not going to be getting the 74 engine. If I were to get a spare engine it looks like I would be looking at a 69-71. That way I won't have to go through all the adaptations. I try to keep everything stock mainly because I have a hard enough time figuring things out as it is. At least I can use a book or get information from the forum when it is stock. How typical is it to have a spare engine and transmission for other Triumph owners anyway? How many of you have actually had to rely on a spare engine or transmission? I plan on keeping this car "till death do us part..." and have other high wear parts I have collected when the price was right.

03-30-2006, 10:52 AM
Too bad you live so far away Kevin, I just bought a '68 TR250 engine as a spare for my '74 TR6.

My reasoning for a spare engine is that it will be less time off the road when I get around to rebuilding it ... I can rebuild the spare at my leisure and then put it in the car over a weekend (I hope).


03-30-2006, 07:39 PM
I've got spare engines and trannies for everything I own.
Some are built and ready for installation, others are awaiting their turn.

03-31-2006, 01:04 AM
I did the same thing, thinking the same thing until my TR6 was sidelined. /ubbthreads/images/graemlins/frown.gif /ubbthreads/images/graemlins/nopity.gif

Anyway, The only pistons available (unless custom made) are the 8.5:1 CR pistons (last time I looked) so even rebuilding the '74 engine would result in a higher compression engine than it was before. The later intake manifold makes better torque. The later dual-down pipe exhaust manifold will help the engine exhale better. When you pull the older engine out just transfer the ancillaries from the old engine to the new engine. No real adaptations to make at that point. /ubbthreads/images/graemlins/thumbsup.gif

Now, if you want it to remain stock looking then the above won't work and you would need to find an earlier engine. But I'm no good for advice on stock appearing TR6's. /ubbthreads/images/graemlins/wink.gif /ubbthreads/images/graemlins/driving.gif


04-01-2006, 06:27 PM
Kevin, The differences between the two engines are not enough to worry about. If the seller is local, go for it. The people on the forum will help with your questions.
As for spare engines, I have a spare engine, transmission and differential along with various other parts. I'm always on the lookout for more parts. Many of the parts have been in storage in my garage and attic for 25 years. I've owner a TVR all during that time, but it is not on the road. In October I purchased a TR6. Years ago when I drove a TR6 parts were easy to find, and cheap. Today they are not as easy to find and generally are expensive. If you're planning to keep it for a long time. Having a stock of spares is a wise investment in my mind.
By the way, the late model head is the best flowing head of all production models according to one knowledgable source in the UK. If the engine comes with an intake manifold you'll be ready to roll.