At the moment I am still trying to sort the motor out on my 70RR. Did a cold compression test with all the manifolds off and got a reading of 105, even across most cylinders. I have been told it should be 150 with a variance of 10% across the range, Chrysler manual say's 100, but not sure which type of motor that refers too. Some Interweb searches say 90 - 110, others say as high as 165. As far as I call deduce, it's a stock 440HP motor, so who is right??? Any info would be gratefully received.
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440 HP2 compression test woes....
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440 HP2 compression test woes....
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A cold engine compression test will always show a lower reading than a test done on a hot engine, this might be where the figures of 150 psi are coming from. You can do a wet test by pouring a tea spoon of oil into the cylinder to seal the rings, do the test again and the reading should be higher. If the reading in any cylinder doesn't rise it's a sign you have leaking valves. The only real way to determine a problem is to do a leak down test, if air can be heard escaping through the carb or inlet it's an inlet valve, through exhaust it's an exhaust valve, through dipstick it's rings, bubbles in the coolant means head gasket.
All you are testing by doing a compression test is any irregularities with the cylinders it won't tell you the cause, that's the leak down test job. But to be fair your engine looks pretty spot on, even wear and no deviation with the cylinders and that's what your looking for.
All you are testing by doing a compression test is any irregularities with the cylinders it won't tell you the cause, that's the leak down test job. But to be fair your engine looks pretty spot on, even wear and no deviation with the cylinders and that's what your looking for.
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