Cbarge - see answere below -
What intake are you running??
Stock 4bbl intake (originally a 2bbl, dad upgraded in the ''70's)
Did you block the heat crossover??
Unknown - I doubt he would have...how to tell?
Original 1966 casting heads??
As far as I know, original heads - car only has 66k orig. miles
Single or dual exhaust??
Single Exhaust
At what RPM does the mechanical advance is "all in"??
My tach wasn't working at the time, but I"m guessing 2500-3000 rpm. I have a new tach, but gotta finish up suspension before I can check again.
If you can provide me a list of things to try/check i'll do them when suspension is done. - Thanks for the feedback!
What year is the intake?? I tossed the 66 4bbl intake for a 68-70 casting.Had a slight rise and flows much better than the 66 4bbl casting.
You can opt for an aluminum Edelbrock intake if you so desire.
To know if the cross over is blocked or not you can check the temp with a laser heat gun between the carb and head where the crossover is located.-or pull the intake.
The reason to block the crossover is to keep the heat away from the gas. The 383 I worked on had a problem with gas boiling and evaporating before it got a chance to burn and that caused ping from a lean-out condition.
If you do not want to pull the intake,at least add a 1/2 inch spacer under the carb to isolate it from the heat.
The original closed combustion chamber heads have small valves and do not flow as well as later 906 or 452 casting heads. Detonation can hurt your heads and may burn a valve or two in extreme cases.
I found burnt valves on the 66 383 and ended up replacing the heads with a rebuilt set of 1976 452 casting heads.They already had hardened valve seats and port matched..
I ran the single exhaust for one year and then installed the TTI dual system.
What a difference..Engine temps went down,MPG went up.I had to rejet the carb and different size metering rods to give her More gas to fix another lean-out condition from the free flowing exhaust.
Running Pertronix I,initial timing set at 11.5 degrees,full advance at 34 degrees at 2400 RPM with vacuum advance NOT hooked up. Engine was retarted which caused engine to heat up and ping.
In conclusion,I had to isolate heat from the fuel system,reduce engine temps,add more fuel and increase air flow to eliminate any ping.
Hope this helps.