[Tommy]

brainsboy -
I'm no expert, but I have had some experience that you may find illuminating. I damaged two pistons on an earlier 351W engine due to detonation. Detonation can be caused by premature firing of the spark plug (i.e., the timing was too far advanced for the combination of compression, fuel octane, air temperature, etc.). Keithc8 (an engine expert) suggested a total advance of 32-34 degrees. In my non-expert opinion, you certainly can do greivous damage to your engine running 42-43 degrees of advance. I'd change the springs right away to bring the total advance down some.