Reply to "ignition timing curve"

Derek,

You should be able to run the lower octane fuel with no problem. To experiment, run the tank almost empty, fill it with 5 gallons of the low octane stuff & give the car a drive. If it pings, you still have room in the tank to add enough high octane fuel to dilute the lower octane stuff.

The "generic" total advance number always given for the 351C is 36 degrees. Total is initial advance plus centrifugal. If you arrived at 20 degrees initial advance using the method I described previously, you would therefore need 16 degrees centrifugal advance (20 + 16 = 36).

The truth is your Cobra Jet motor with open chamber heads can probably use more than 36 degrees total advance. BUT, nobody can give you the proper number for your car without testing it on a dyno, the needs of your motor are highly dependent upon a myriad of factors including the octane of your fuel, the design of the cylinder heads, the specs of the camshaft, the design of the intake & exhaust systems, the calibration of the carburetor, etc..

There is an "on road" method to determine what the best total advance for your car is, but you need a lot of open road where you can drive fast. The best total advance setting will allow you car to pull higher rpm when wound out in the higher gears. The Pantera can go pretty fast in 5th at red line!

One last thing, the calibration of the timing marks on the harmonic balancer ARE NOT accurate, I guarantee it.

Your friend on the DTBB, George