6* but I'll never set anything at less than 10* advance... If it pings, I'll recurve dist and shoot for 12*-14*...
SBF's of that era ran better, cooler, peppier, with around 12* ignition advance. Had a lot to do with the wedge combustion chamber designs. Once Ford came out with the GT40P's and their centrally located spark plug you could back down to around 8*.
I hung up my timing light in favor of a vacuum guage. Timing by engine vagume is the best method hands down. Not only is it more accurate, it automatically compensates for chain/dist wear. And it is also an opportunity to adjust your bleed screws. its a diagnostics opportunity as well. Vacuum guage is to an engine what a cardiogram is to your heart. It tells of wear, bad valves and other internal vitals. Super easy. Plug guage into port vacume (hot idle) Advance timing untill max vacume. Back off 1-2 inches of mucury on the guage. Set distributor and test drive. If you get ping, back off another inch. Now set you're idle screws. Guages flutters in time with motor? Noooooooo..... Sad day.
One way to find out what your engine wants for initial timing is to warm the engine up to operating temperature, then advance the timing two degrees, shut it off and try to restart it. If it starts easily advance the timing another two degrees, let it heat soak for a minute, then try to start again. If it easily starts, advance the timing two degrees again, heat soak, try to restart. Keep doing this until the starter drags or kicks back or you get a pop through the carb. When that happens pull two degrees back out and lock down the distributor. The only time this doesn’t work is with a really high duration/high overlap cam. Had a cam once with 300* advertised duration. Got up to 21* initial and stopped. That cam wouldn’t idle under 1100 rpm and 18* initial. Total advance is the most you can have with your engine under heavy load at wide open throttle without pinging.
On a stock engine with operating vacuum advance, will probably have ping at part throttle and very possibly have knock at WOT.
I guess you won't know until YOU try it. That hasn't been my experience. It may turn out that the amount of advance you end up with is close to your arbitrarily chosen 10*-12*. I've done this with basically stock engines and 36* in the timed port-connected vacuum can. The starter would drag at 16* and I backed off the timing to 14*. Had no drivability problems.
I did same eons ago, had a '69 Ranchero I ran 14* lead but had to disconnect vacuum advance to eliminate ping. Cranked hard when hot at any higher timing lead. It had the same 302 that's in my Fairlane(K280S, Fairlane still has it's tag plus have build sheets for both). At 10* adv it's engine idles 20.5" vac at 600 rpm, has instant throttle response(if ye ain't ready you'll get a surprise). Thought maybe installing a larger than stock 429 2bbl carb would reduce off idle response, only made it sharper. BTW Fairlane is still running points ignition & orig coil.
