Max wedge ignition issues

[63PlyMoepar]

I have a 68 440 with Max wedge set up.The distributor has a Pertronix electronic ignition set up. I was told that the engine has around 10.5 11.1 compression. The guy I bought the car from only ran 110 octane gas in it and it ran great. Since I have not run 110 and have been running 94 and it is pinging really bad. Is there a timing sweet spot that would allow me to run the pump gas and not have the engine detonation that I am experiencing now. Thanks Paul

 

[turbine68rt]

What are your current initial and all-in settings?

 

[63PlyMoepar]

The car is now at my mechanic’s house. I bought the standard Mopar conversion kit thinking that I needed it,before talking to the previous owner and telling me that it had the Pertonix kit on it. Tomorrow is when I will know what it is set at currently.

 

[AR67GTX]

You may need to install a FBO advance limiting plate in the distributor to cut centrifugal advance to around 16 degrees. Then try 18 degrees of initial timing (34 total) and see if it pings. If so take another degree initial out.

If it runs clean at 34 total, then you could try bumping initial another degree and see if it’s still good. If your starter complains at that on starting, you can reset the advance limiter to 18 degrees and run 17 degrees initial timing.

If that 94 octane gas is by the R+M/2 rating method it’s pretty near equal to a 98/99 octane premium fuel from the 60s.

 

[Don Frelier]

Short term take a sharpie and mark the distributor in a convenient location.
Loosen the hold down clamp and then rotate the distributor counter clockwise try a 1/4" at a time and then test drive at operating temperature.

 

[Geoff 2]

Your problem is not the ign system, it is the 11:1 CR, combined with 60s cyl head design, that is causing your problem.
The Max Wedge intake isn't helping either. Chrys had to use crazy jetting settings to compensate for the design. This can lead to some cyls running lean & that can cause/aggravate pinging.