70 Challenger. 410 stroker pings only at very high speeds and rpms. Do I need to richen the secondary circuit in the carb or what. Total timing is 34 degrees

More than likely, your vaxcum advance is adding too much. Disconnect and plug the vacuum advance at the carb side. If the ping goes away, you have your answer.

At what RPM/in hg does it start to ping? What RPM do the springs (slots) max out at? when it starts to ping are you on the cruise or power circuit? (what PV/metering rod springs?) Depending on your DCR you may need more octane & if you dont want to upgrade then yes it'll have to be detuned (assuming no system is way out of whack here that NEEDS to be changed). What is your cranking compression & what octane? You might turn the can 2 or 3 turns CCW with the 3/32" allen wrench & retry. Until you solve it stay in pinging mode as little as possible as it is extremely damaging to the eng.

Sounds like a lean miss up all jets a couple sizes and try that.


What Carb.

I'm at 9.7:1 measured compression with my 416 stroker with aluminum edelbrock heads. 236/242 @050 cam

With 91 octane gas out here, I'm at 32 degrees total. 34 would ping.