ptilden

I performed a leakdown test on my original never rebuilt 1970 455. The driver side was 96, 94, 96, 94%
the other side was 93, 92, 88, 92%
from my experience, this is pretty good. I have "E" heads, and could this test reveal whether or not I have hardened seats or not??? The engine has 45,000 original apparently well maintained miles. Also, could the difference from one side to the other reflect the usual difference in the deck height on these engines?

442Harv

Leak down test will not tell you if you have harden seats. Also E heads where not harden seats, 71 G were the first year.Your test shows the cylinders, are not that far off. The lowest one, just probbly has a more worn cylinder, or valve. Give it a compression test also, that will tell you more if the compression is good or not. The leak test will tell you where the leak is, if there is one. Really need to do both.