Well I also have a 383 that likes extremely advanced timing. After converter, carb, distributor, spark plugs+wires swap, compression check, cam swap to lunati 60302 and many posts at cc.com A fellow member diagnosed low static compression. I got 120-140 psi (not bad according to FSM) and no leaks, but the car is slower than it should be with stock 383.
Setting even 20 btdc of initial and 24 of mech advance does not lead to pinging! I drive it with 18 iniial and 24 mechanical and have to live with it, at 10 btdc of initial it was running unevenly and at 0 btdc almost died.
So are you sure about the compression of the rebuilt motor? You used dome pistons so it depends on chamber cc. Did you zero deck the block?
