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TR2/3/3A TR3 engine compression

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bluemiata90

bluemiata90

Jedi Trainee
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I'm in the process of restoring a 61 TR3 with 45000 original miles on it. I'm redoing the body,frame and suspension. I've been debating on if I should have the engine rebuilt(money is becoming a factor). The engine seems of sound and run fine, but I've only driven it about 10 miles since I bought it. I was told it ran great before it was put in storage 2 years ago. I've done a compression test on the cyl. and they came up 180/180/188/180. These figures sound great to me, but I haven't been able to find any information on what the correct readings should be for a engine in good working condition. I'd hate to not rebuild it and put the front nose back on and in a couple of years have to remove it to rebuild the engine later. Do these pressures sound good?. What are the correct pressures?. This information will determine if I rebuild the engine or just replace the oil,water pump, etc. If possible, reply to this site and also to bluemiata90@hotmail.com.
thanks
scott /ubbthreads/images/graemlins/driving.gif
 
Well those numbers sound very good to me. In my experiennce compression gauges are not particularly accurate but their measurments are useful for comparing cylinders. As your readings are fairly consistent I would take that as a good sign.

Of course other things (oil pressure, what comes out the tail pipe, oil consumption, overall performance, etc) will give you additional clues to engine condition.

My compression was sound and other factors seemed okay so I decided to hold off on a rebuild for awhile. That was 23 years ago. Sometimes you just drive 'em and enjoy 'em.
 
I was hoping someone would tell me to just hold off and see. As I mentioned before, the engine sounds strong and except for minor smoke when warming up (which I think is do to old gas) the engine runs good and the oil pressure seems fine. Considering the compression numbers sound good, I think I'll just add new exterior parts and new gaskets and just enjoy it. If anybody else has an opinion on this, feel free to add it. Do I rebuild or drive?
 
Scott Rule # 1 If it ain't broke, don't fix it. That sounds like great compression and like George said the balance is really good. If you were building a concours car then you would want every nut & bolt apart but I say get her back on the road and drive. Good luck!
 
Drive it! Absolutely! I assume you got those figures testing "wet" i.e. with a squirt of oil in the spark plug hole first, but they are very good. I think you don't need to be concerned until the range exceeds 8-10% from best to worst, even the just a valve job on the cylinder head will often be good enough.
Your smoke may be oil smoke from valve guide wear, or even just normal because there are no seals on the valve stems of this engine. Again , don't worry, sounds like you have no problem. They are very tough engines, mine was rebuilt by a previous owner in 1973, still running well!
Simon, TR4a.
 
If all you are worried about is removing the nose in a couple of years, I say just run it as it is. The nose can be taken off, and engine out in about as much time as it would take to do the Timing Belt on your Miata.

Yeah, I own one of those also.
 
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