1979 70 Johnson -- "dead" cyl w/ good spark

When I took the boat out this spring, it had nowhere near full power. Squeezing primer bulb has no effect. #2 plug is consistently wet & black. Replaced coil, wire, and plug, but still no fix. Took out on the lake and ran WOT several minutes (never getting above 4000 rpm), then hooked up a spark tester to #2 -- shot blue snapping spark over a half-inch gap, so I'm getting good spark when hot. Compression gauge showed 120, 117, 115 psi hot. (Covering bases: recently cleaned/rebuilt carbs, fuel tank vented, good new fuel). Noticed, however, that the #2 plug did not go in/out smoothly and there were shaving in the threads.

Could loss of compression around plug threads (which didn't show up on the gauge because of its O-ring seal) be enough to cause this big an issue?

Re: 1979 70 Johnson -- "dead" cyl w/ good spark

did you remove and clean all 3 jets? read TOP SECRET FILE. did you get the jets back in the proper place.