I have a 454 Chevy in a jet boat. I have been chasing all kinds of problems since a local auto store did a crappy job on a rebuild many years ago. Being that it is in a boat has taken longer than usual to comb through everything. However, I have a high pitch squeak and backfire coming from the valve terain on the right side of the motor.

I do not know how to begin to tackle diagnosing the problem so I can fix it. It is running hudraulic lifters and roller rockers on aluminum heads. I don't know weather it is a valve or a lifter or what cylinder it is coming from. Could the valves need readjustment? I imagine for some reason something is causing a exhaust valve to be out of adjustment and causing a backfire... If anybody has any experience or ideas dealing with this I could use some help.



Thanks.