HEI distributor tuning problem

[JOJABOY]

Originally Posted by WadmalawJoe

Alright I have an update, I bought a vacuum pump and a multi-meter that had the tachometer feature as well.

So here are my findings;

With advance unplugged and port capped
RPM's drop to 650 and timing is 12 degrees ahead
Rev up to 3,000 RPM's and timing goes to 32 degrees ahead

With vacuum pump, I pumped it to 10 and checked everything, then pumped to 20 and nothing changed so I left it at 20 for testing.
Idle is 820 RPM's and timing 30 degrees ahead
Rev to 3,000 RPM's and timing goes to 50 degrees

So what's my next step?

Those numbers sound good. So now you just have to figure out what is finicky about your particular engine. Keeping in mind that different cams, plugs etc. will cause your engine to differ from the standard curve. I would try backing my initial timing from 12* down to 9* or so.

50* is your "all in" and that seems to be causing predetonation and causing the noise. But before you adjust the timing. Try this first.

Unplug your vac advance from the carb port and cap it. Then plug it into the intake vacuum. (the port on the very bottom of your carb) Take it for a drive then revisit your timing curve. Worth the try. Only take 30 seconds to switch it to the other port and the drive time.