67mustang302

Backfiring through the carb 99% of the time is too lean of an accelerator pump shot on the carb. If the jetting is lean(explains pinging under load with minimal timing) then the carb will need a bigger pump shot to cover the transient lean since the mains take longer to pull fuel through a smaller jet when it first generates signal.

Set base timing at 8-10 and total timing at no more than 28-30 and then go drive it, if it pings then it's probably too lean.

What do the plugs look like?

Houndstooth

I just replaced the plugs, the old ones didn't look fouled though. I dialed the timing back to 8* and it is running perfect, no backfiring or pinging anymore. It was backfiring through the carb when the timing was set at tdc. Don't know if this still means it is running lean or the coil is bad.

67mustang302

Are you sure the balancer hasn't slipped and it's not showing the correct timing?

Houndstooth

No I'm not sure. Is 8* advanced too little for a 302? I'm really happy with how it's running right now.

Gun Jam

no 8 at idle is acceptable...especially if you think its running well.

-Gun

Houndstooth

Well it started pinging again. I was in 2nd gear and accelerating when it happened. I'll check the timing tonight to see if it has changed. I've never messed with the air/fuel mixture on the carb before, a little afraid of screwing it up.