hi i need to know the specs for timing advance on the 351 clevo, its in a boat do u check this at idle speeds?

what heads?

and being in a boat its simple. lock the dizzy so it has no mechanical or vacuum advance and set it at 32 degrees if its got iron heads or 28 if its got good alloy heads.

If its got cheap procomp heads the timing should be the least of your worries.