My 370 started knocking the other day and acting like its running lean, hesitant and popping and not running as usual. All the plugs look good and look the same, all the cylinders had 190-195 lbs compression except for 7 that had 235lbs!! I tested it 4 times and everytime it was 235lbs. All tests were done with the fuel pump relay disconnected with the throttle wide open. Its got l92 heads milled .030 with Comp OE lifters. 244/248 .612/.615 cam, 7.35 pushrods. Next up I'll try a leak down test and if can find one. My first thought was possibly a collapsed lifter on the exhaust, not letting exhaust out and its coming from that general area. Any other thoughts?

 

some sort of debris in the chamber?? have you borescoped the plug hole?

 

turn the motor and look at the springs for that that cylinder. if its collapsed u may be able to see it doesnt move. if the valve is not opening you'll definitly get that popping

 

I broke a few springs one day and had a similar issue. Never checked compression though. Pull the valve covers off and see what you find. #7 was the first one of mine to break

 

Tyler, ever figure this out? I'm having a similar issue, but no knock or misfire codes. Although, my compression test also shows all cyl's at 150psi.