I dont really know whats its supposed to but I had an urge to do a compression check on the boat last week and here are the results.. Cranked each one about 8x to reach the readings
I didnt realize that Im supposed to test the rings using regular motor oil when doing a compression, I used WD40 instead, Cyl 4 jumped to 110 and 3 went to 110 also, none of the other changed when using WD40. I will have to re-check with an oil squirter.
Its a '90 stock 454bbc by Hardin Marine 4-bolt. Its never been rebuilt to the best of my knowledge.
All of the plugs were black around the bottom ring, but the ceramic was white, ground electrode were clean, and some of ground electrodes were even a coffee/mocha color, but not all of them, the others were just clean. They are brand new plugs MR-43T's.
Based upon the compression, does this thing need a rebuild?