Had my mechanic fix ign issue/arching spark from wire to coil. Replaced plugs, wires, coil. Now he reports no compression #4 and #6. Call engine builder, says to check valve adjustment, as maybe he torqued rocker arms down too tight/valve cracked open...mechanic didn't check this and will check it tomorrow, however adjoining cylinders strongly suggests blown head gasket. Only 4 hrs on this engine. Engine never overheated. Either way my engine builder is responsible since he should have adjusted the valves correctly or at least advised me to do it if he didn't.

sounds like a head gasket to me..the valve adj would have to be WAY off to have 0 comp, do a leak down you will know quick

The mechanic is assuming bad compression on those 2 cyl, ie he didn't actually do a test, he just did the pull off plug wire one at a time test, and when he pulls off 4 and 6 there is no change in idle. Brand new plugs, wires, cap+rotor. Could the mod in dist not be firing on 4 and 6 for some reason? I'm mtg him down this morning to do some more tests.

check your fireing order first 18436572,, too easy yo cross wires..

confirmed comp test, little or no compression in #4 and #6. Must head gasket. Pulling boat out of the water taking it back to machine shop. another lost weekend!!