compression different side to side
You could also rent-borrow a bore camera and pull the plugs to have a look at the piston tops and look down the intake runners. You can easily see carbon tracks on the runners if the valve seals are leaking.
Are you sure both heads are the same and before you installed the heads did you check the valve depth? I've seen were the valve seats are cut too deep in one head and the other are high. This will cause completely different compression readings side to side.


