manifold vaccum for vaccum advance ?'s

...............Just remember that Don is not GOD.........manifold vacc is 4 chevys...........the popping out the ex is because ur motor can only tolerate so much timing......obviously u have too much......dont forget, the heavier the vehical the less timing it can tolerate..........go to 12* initial.......+18=30.......then set vacc to 10.....12+18+10=40........anymore ur asking for detonation [that u cant hear] melt a piston.....kim.......