pinging-detonation

[rup]

need some help, got a ping.
Panhead 90ci (AE Engineering)
S&S Carb
Andrews BH Cam
striaght pipes with baffles
Mallory distributor
Plugs look good (nice color).
Timing dead on.
New 91 octane gas.
Carb cleaned
live at sea level
Ok after warmed up (2or3 miles)when I get on it, that;s when the pinging starts (level road) get off it the pinging stops.
At idle seems the front cyl is popping twice (only one is detonaing) to every pop of the rear Did nothing to it this winter ran great last year.
Thanks
John

[nauipro]

Hey John, since this is a new problem you probably want to look at what might have changed. Is it possible that the "new" 91 octane fuel is not what it seems to be? You may want to drain it and start over with fuel from a different source to be sure. After that I would be curious to see what the ignition advance is doing. I'm not familiar with the Mallory distributor, but if it has weights you will want to make sure that they are free and not stuck at full advance. Do you have a VOES on there? Is it working? A lean fuel mixture will also cause detonation so a manifold leak or restricted jet could be the problem............Bill

[rup]

Thank for all the help, but I think I found the problem.
I switched to Accel plug from Autolite 4265 when the parts guy cross
referanced he gave me the Accel 0494 (Cold plug) it should have been 0496 (hot plug) Remember start easy first It always the small **** that gets Ya.
thanks again

[nauipro]

Originally Posted by rup

Thank for all the help, but I think I found the problem.
I switched to Accel plug from Autolite 4265 when the parts guy cross
referanced he gave me the Accel 0494 (Cold plug) it should have been 0496 (hot plug) Remember start easy first It always the small **** that gets Ya.
thanks again

I may have read your post wrong, but a hotter plug will make it more likely to detonate. Did you mean that he gave you a hot plug and you need to go colder?..............Bill

[claydbal]

Originally Posted by rup

need some help, got a ping.
Panhead 90ci (AE Engineering)
S&S Carb
Andrews BH Cam
striaght pipes with baffles
Mallory distributor
Plugs look good (nice color).
Timing dead on.
New 91 octane gas.
Carb cleaned
live at sea level
Ok after warmed up (2or3 miles)when I get on it, that;s when the pinging starts (level road) get off it the pinging stops.
At idle seems the front cyl is popping twice (only one is detonaing) to every pop of the rear Did nothing to it this winter ran great last year.
Thanks
John

how many miles on motor? have you got an engine built for panzer? AE no longer builds a 90 inch motor!
sent you a PM

[rup]

Only 3100 miles, yes built for Panzer.

[rup]

Originally Posted by nauipro

I may have read your post wrong, but a hotter plug will make it more likely to detonate. Did you mean that he gave you a hot plug and you need to go colder?..............Bill

No you did'nt read wrong I just went back to what setup i had last year (plugs, air filter, timing) and also replaced the gas.