340 with edelbrock heads overheating
IIRC my initial is 18 and I have the FBO plate dropped into the 14 slot giving me a 32 total. I am just getting started, & expect to tweak it some. I used a vacuum gauge to get the initial, this was how someone told me years ago, but I had to search around to remind myself, had been out of the car game for a while.
Gauge connected to manifold source. Make sure no vacuum leaks, vacuum advance disconnected and plugged, Advance timing. Each time RPM & vac go up, reset RPM back down & repeat. once you reach as much vacuum as you can, back your timing off a couple degrees. Probably find yourself close to 20 somewhere.
34ish seems to be a good starting point for TOTAL (this is NOT incl. vacuum numbers yet), so - Subtract your new timing from 34, and that is the # slot on the FBO plate to start with.
#1- Listen for any pinging, dial it back 1 or 2 before going any further