Carburetor, Gas, Carbon, Timing?

CC: I have a 1964 SS convertible with a factory 300hp 327ci engine. It pings above 3500rpm at more than 3/4 throttle. It has an Edelbrock Performer manifold with a Holley 600 vacuum secondary carburetor. There are also headers and a 4-speed behind it. The problem didn't start until they started selling oxygenated gas year-round here in California. I've tried premium with octane boost and even replaced advance weights and springs (stock distributor with Perluxe electronic pick up-no points). All plugs and wires were R&R'd to no avail. Timing is same as before and carburetor was rebuilt just to eliminate that as a problem.

SC: It sounds like predetonation (pinging and knocking) caused by low quality or low octane gasoline. Try using a genuine Octane boost or retard the timing a few degrees. Your 300hp 327 probably has high compression (11:1) and was designed to run on high octane leaded gasoline.

S_: If you're sure that what you're hearing is pinging, I recommend you double check the operation of the carburetor power valve and also check your fuel pressure/volume. If the engine goes lean, it will detonate until it puts a hole into a piston. This will not make you smile. Most pinging happens at low rpm/medium or heavy throttle. Higher rpm pinging is kind of uncommon. Do you have dark smoke coming out of the exhaust when you're hearing the noise? Perhaps we're dealing with carbon knock.

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