360 mystery breakdown

MOPEkidD-3 said
I did spend a lot of time playing with the ignition timing, seemed like every year or so I was backing it down a degree or two more than the previous year even running the same grade from the same station (I know still varies). Last I had it was 32* total all in at just under 3000 RPM. Head gaskets were Fel-Pro 1008s. Cranking compression was 170-180 psi on all cylinders taken just this past summer, pretty substantial for 5000' above sea level I think.

Looking at head gaskets now, same situation it was 7 years ago... if I want the ideal quench with a .030-.035" compressed height I gotta pay 2x as much for Cometics. Fel-Pros only come in .039" and .028" which I think would be pushing it (would it?). It's all speculation anyway heck I'll probably want new pistons.

In your case...you shouldn't need more than 30 degrees of timing "on premium". You only need as much adv as the octane can resist the cyl pressure or the pressure will light it for you. The gasket pushing into a water jacket sux, half the time or more when they go do to detonation/pinging they push toward the valley and you avoid the water.
I use 8553 head gaskets, 185 cranking, quench domes with j heads and BPR5EY plugs. 28 total timing by 2200rpm on 91 w/4 spd. If I run anymore timing then go down the freeway and at 65 cruise decide to stomp on it....it will rattle and you bet your *** the second it did I lifted out and was back in the shop checking plugs and taking timing out 2 degrees at a time. Pistons are a nice golden color, pretty clean with light film on them. The pistons mirror the chambers ....remember that when tuning.
Your cyl pressures are wide spread @ 170-180...you could have been better with a tighter quench...but really you ran too much power timing.imo