I'f I do a compression test on a 1971 455 TR code what should it read? I'm told the engine was rebuilt roughly 10,000 miles ago.
Johnno, You aren't looking for a specific # in this case, but uniformity of readings. The interaction between cam and compression affects the readings. The lowest reading cylinder should be at least 75% of the highest reading cylinder. Those are Buick's standards for satisfactory compression.
My stock 71 read about 120-130lbs when I first did it. I now read 145-150lbs. But as Larry said, you are looking more for uniformity in numbers.
Thanks Larry and Adam, the test showed 7 cylinders at 150 (almost exactly) and one at 140. The engine was on a stand and we only ran it for a minute or two and then did the test. I should be all set. Thanks again!
