I have a 1980 Z28 with a rebuild 350 in it......When the engine warms up, it begins to ping under load.
Bit of background..
Does this engine still have pollution stuff, egr etc on it?
What dizzy is in it, the orginal 80s or post mid 70s?
Is the detonation at WoT or low mid loads or both?
And at what rpm range is the ping?
Do u have a choke on the carb?
post mid 70s dizzies have to be converted to pre polution curves..in most cases the there is enough in the post 70s dizzy to convert with a little bit of compromise, but in my experiance reading what u are doing u have a dizzy the may need more than that in the curves.
If have a choke, at cold then engine runs rich... even without a choke runs a little richer till warms up... If the carb is close on tuning limits / mixture requiements it may need jets or powervalves (depending on rpm range and load it pings in) looked at
Now why would you want to run as much initial as possible up to the point just before it starts lugging the starter?
I can see the logic in that....more intial (not idle intial+Va) the more load put on the starter....more load higher current drawn...And yes I have seen big ampmeters used to watch starter loads and ID intial and starting issues... Factory can be anything from a few degrees before TDC to just under 10 degs depending on the vechile/engine...When one watches the amps, getting up over 10 they start climbing, get over 12 and climb fast, and varies as to cam profiles.
This is a basically stock + a bit engine so keep that intial 10 or below...
Idle (intial+ VA) in the 14 to 18 deg range
Total (intial +cent) between 32 and 36 degs around 3200 rpms...
Keeping everything below 40/42 degrees (intial+cent +VA)
Have the cent come off around at least 300 above idle in N rpms...better for a street around 1100 to 1200 ....if around the 1100 this means will have resonable springs in.
From there if still pings the chances are the carb is too lean.
1st check for vaccuum leaks including things like secondary butterfly gaps and the mixture/ idle sped screws are aprox 1 1/2 turns +/- 1/4 turn.