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Triumph TR6 - Machine Shop Services

Ok .. Here we go .. first post to the board.

I've got a 72 TR6 that I've owned for 24 years. The first year I spent thousands fixing up the engine and for the next 20 years I really didn't do anything to it. A couple of years ago I decided I'd try and learn how to fix things on the car and now thousands of dollars later I've changed out pretty much everything except core engine components. On the weekend I decided to do a compression check in search of why the engine seems to run a little lumpy.

The results weren't good .. compression readings around 130 but with one cylinder at 80 and another around 100. Given that I've only put 18K miles on the engine after the block was bored out +.030, new pistons installed, new con rods and bearings, new oil pump and a couple of valves replaced I figure the likely culprit of the low compression, lumpy idle is the cylinder head. (I've already changed all the minor components (rebuild kit) on the carbs, electronic ignition installed, new plugs, new wires,new coil, new rotor, timing set etc.)

I'm assuming the list would recommend a leak down test to get to the bottom of what might be the problem?

And...the likely next stop, after the driving season is the machine shop ... are there any recommendations for shops in the Milton/Burlington/Oakville/Mississauga area? Thanks.
Sean McCafferty


You might just start by squirting some oil into the low cylinders through the spark plug holes. Then redo the compression test.
If they come up it's in the rings if not, the head. If I'm understanding you right the engine was done 20 years ago but you have only put 18K on it. If thats the case it maybe simply the the rings are sticking. I had an engine (not TR6) that had a low cylinder. I used some engine flush, fresh oil and an additive. Just like magic you could hear the rings let go and the engine smooth right out. Usually life isn't that easy though. Hope that's your problem.

Doug Campbell

Sean, if you can find someone who can do a leakdown test, it should tell you. From what Clive explained to me, and from what I watched him do, compressed air is put into each cylinder with the piston all the way up. A gauge tells you if it is holding 100% or 80% or whatever of the pressure. If it is holding less than 100%, that means there is a leak or improper seal somewhere. Depending on where you can hear the leak (through the oil filler, through the carbs, through the exhaust), a knowledgable person can tell what the problem is.

Clive understands it, I don't, but that is my best layman's understanding.

JL Bryan

Sean before you do anything drastic It sounds like you have a few gummed up rings. Remove plugs and inject parafin or a similar fluid to free the piston rings. It sounds like the old Use It or Loose It syndrome
Clive P

This thread was discussed between 24/05/2005 and 25/05/2005

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