The Stovebolt Site Forums The Shop Area Engine Shop Compression Values

Generally speaking, you want no more than 10% variation between cylinders. When you run your compression test, see if squirting engine oil into the spark plug holes raise the compression to within 10% of each other, and higher, generally. If it makes a significant difference, then ring seal is compromised and you need a rebuild. If not, then perhaps your problem is the head needing a good rebuild. That should point you in the right direction.