383 timing, and engine "pinging"

[71 Bee Man]

G'day guys,

my 71 Superbee has a 69 383 in it. It is running an Edelbrock 750, and also has Mopar Performance "Orange" E.C.U and a MP distributor.

My problem is that the car absolutely "pings" it's head off. I'll admit it was advanced a little, but even today at around 2 1/2 B.T.C it was still pinging under load. I've just adjusted it to about 2 degrees A.T.C and going to see how that affects it.

I only use 98 Octane Premium fuel in her.

Does anyone have any suggestions or advice ? I'm only a backyard mechanic, and the car actually drives quite nicely under normal, easy going, conditions. But when you accellerate a bit hard or on hot days then the pinging is easy to obtain.

The motor itself doesn't appear to have any severe work done to it - I'd say it's pretty standard aside from the bits I mentioned.

Finally, does anyone have the exact timing and tuning specs for this motor ? Here in Australia they're not on the shelf.

Peter
Sydney, Australia.

[deputycrawford]

Check your total mechanical timing and then your vacuum timing. Your total mechanical timing should be around 36ish degrees. You might drive the car without the vacuum plugged in at all. Just plug the port at the carb and time the car to 36 degrees at 3000 rpms. Vacuum advance was only used on stock vehicles to get the most gas milage out of it for EPA and bragging reasons. 90% of old cars have ditched the vacuum advance. Also, do a compression check. Cylinder pressure that is too high will ping forever. Start with the timing and let us know.

[Mr.Sixpack]

I have had problems with mopardistributors for electronic ignition conversion, the vaccum advance is to big even if I put the timing at 0 deg the total would be 40-42 deg. The easiest fix was to remove and plug the vaccum advance.

just my

[chargerbr549]

another thing you might check is that the your crankshaft dampner hasn't slipped and you might be alot farther advanced than what your timing mark is showing.

[71 Bee Man]

Check your total mechanical timing and then your vacuum timing. Your total mechanical timing should be around 36ish degrees. You might drive the car without the vacuum plugged in at all. Just plug the port at the carb and time the car to 36 degrees at 3000 rpms. Vacuum advance was only used on stock vehicles to get the most gas milage out of it for EPA and bragging reasons. 90% of old cars have ditched the vacuum advance. Also, do a compression check. Cylinder pressure that is too high will ping forever. Start with the timing and let us know.

Thanks for the input guys.

I'm working the next couple of days, but I'm going to see what the mechanical timing is. Someone recommended that once before but I couldn't find the thread.

Incidentally, last night I had the timing set pretty much at T.D.C.....seemed to run OK with no pinging. Mr.Sixpack may be onto something.

Peter

[71 Bee Man]

Check your total mechanical timing and then your vacuum timing. Your total mechanical timing should be around 36ish degrees. You might drive the car without the vacuum plugged in at all. Just plug the port at the carb and time the car to 36 degrees at 3000 rpms. Vacuum advance was only used on stock vehicles to get the most gas milage out of it for EPA and bragging reasons. 90% of old cars have ditched the vacuum advance. Also, do a compression check. Cylinder pressure that is too high will ping forever. Start with the timing and let us know.

Came home from work and took the car for a good drive....timing at TDC.......no pinging.

I wouldn't have thought it needed to be so retarded, but there you go.