How to adjust the timing out of the distributor.
5 Deg BTDC setting at idle (about 650 – 850 rpm) with vacuum hose to distributor plugged.
When it is hooked up again should run at about 10-12 deg. BTDC
Also make sure that the weights inside the distributor are working freely. And that vacuum canister on side of distributor is working OK. These are prone to split diaphragms on these. You will go nuts trying to tune it.
On any engine I am looking to get the top performance out of, I advance the distributor until the engine pings and then back it off just a bit. I do this at 3,000 rpm. The higher the octane the more advanced you will be able to obtain.