As of late, with the hot humid weather, I have had pinging, popping out intake and exhaust. I have played around with valve adjustments but thinking it is timing. I plugged the vacuum advance it ran much better. It only pops with the choke on now. The carb is fairly rich at idle and not sure at cruise. The Mallory breakerless has a fairly fast curve, in by 2500, 37 total. My specs are 9.5 to 1, 204/214 cam, custom Qjet with XR5 NGK spark plugs. I have really cold extra set of 5670-8 plugs which are super cold. Would something in a 6 or 7 range be better than my current 5? Would an overly rich mixture cause pinging? I assume this is pinging popping out the intake and exhaust?

 

Have you calculated dynamic compression? With that cam and compression, the intake closing event might be too early.

http://www.wallaceracing.com/dynamic-cr.php

 

I wonder how it would run with racing fuel in it instead of the junk gas from the local self serve?

 

Probably better on race gas. I get 8.8 to 1 dynamic and cranking psi should be 180. Plugs look a nice medium brown except 2 and 8 were black.

 

A rich mixture might be causing incomplete combustion.
I'd work on the carb & make sure the thermac system is working (if you have a stock air cleaner).

 

No noticeable pinging today and very humid. I have a hood scoop feeding into a 14 X 3.5" tall K&N filter with filter top.

 

Assuming the 8.8 to 1 dynamic compression ratio calc is accurate, that is huge. I'm guessing the combination of your cam and compression is way too much, even for 93 octane. The intake valve closing event (ABDC) has the biggest impact on dynamic compression.

My dynamic is 8.5 to 1, and I run 93 octane with Octane Supreme TetraEthyl Lead additive (increases to 94). I also run 34 total mechanical advance, and I limit my vacuum advance to 10 degrees. With a 265 DEH cam, my ABDC is 58 degrees.

What's your intake valve timing on that cam? The closing event (ABDC)?

 

28 abdc, cam is advanced 2 degrees on my Cloyes set. I should redo the compression test, was 155-170 but ran atf through the motor, might be higher. My 1.72 ratio rockers should also help bleed off a little more pressure.

 

Only detonated pushing it really hard last night. Filled it with premium before the big price jump.

 

28 ABDC seems really low, maybe that's BTDC? My BTDC is 27, my ABDC is 58. Take a look at my camcard...

http://www.compcams.com/Company/CC/c...csid=1179&sb=2

Which brand of cam are you using?