Thanks guys for the primer on timing. You've answered my questions but I can't answer many of yours. I gotta confess that my mechanic actually timed this particular truck and my original post was based on past experience with my old GMC from 20 years ago.
It does have fresh gas in a vatted gas tank, don't know compression ratio, it has about 80 miles since a complete rebuild (which I don't know much about since this motor is an Ebay adventure), I'm thinking the idle was high (1200 RPM per Tach)when they set it because I had to back off the idle screw. I assume the vacuum advance was disconnected and the source plugged cause even though this guy is kind of "shade tree" (which is a good thing), he's cheap.
Anyway, you've addressed my main concerns which were: I don't need a tach to set timing, just low idle. Pinging means it may be too far advanced. A Petronix point replacement is worth getting.
Thanks again
