compression on a 308

56starfire
56starfire Expert Adviser
edited November -1 in HUDSON
I have a 49 coupe with a 51 308 and 308 cast iron head. This weekend I did a compression test on the engine. I did remove all plugs and turned the engine over a 2 or 3 times until the needle would not move any higher. My readings we 90lbs to 102lbs in each cylinder, I did a dry test only. This sounds a little weak, am I ready for a rebuild? The engine doesn't smoke but I was going to adjust the valves and do a tune up/ and rebuild the carb. I'm not sure how many miles are on this engine, the previous owner has passed away and he is the one that switched the motor out.

Comments

  • Park_W
    Park_W Senior Contributor
    I would leave it alone. Those compression figures are not bad for one of these engines with some miles on it.
  • MikeWA
    MikeWA Senior Contributor
    I'm with Park on this one. The readings are a little low, but are close enough to each other that it should run out OK.

    Lets face it- these engines were at the top of the curve 60 years ago, but even at their best, they wouldn't be impressive against modern big blocks, unless modified. "If it ain't broke, don't fix it."
  • Geoff
    Geoff Senior Contributor
    I too agree that you should leave it alone. Even compressions are the key to smooth running, and the actual reading can vary according to whether the engine was thoroughly hot when the test was done, the cranking speed, and the grade of engine oil used.
    Geoff
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