My El Camino has a rebuilt 454 with HEI and Holley 650 spread bore carb set up. The car seems to run fine up to about half throttle. When getting deeper into the throttle I seem to get a popping through the carb and some heavy pinging. I recently went throught the carb accellerator pumps (because of leakage) and replaced the plugs with Delco R45T and MSD 8.5 super conductor wires with no change. Is it possible that my timing is too far advanced? (It is currently set at specs.)
I also have a slow crank on hot start up's. Thanks for any tips that can be shared.

Sounds like the secondaries might be lean. I'm not up on spreadbores and don't know how you would richen them. Pinging could be timing, although the stock setting shouldn't do it, or a lean condition. Also, a hot engine can ping. The distributor could have too much mechanical advance in it. My experence, quite limited, is stock distributors just keep on advancing. Not necessarily what you want.

Those plugs might be a little hot too,I have a 73 truck motor in mine and stock plugs are r44t and I run r43t's in it. It sure sounds lean to me,cranking slow can be timing or bad wires or bad ground to the starter too.

Ron,
This is also a tell tale sign of a cam going flat.

Thats possible too DZ, but my sons always had lifter noise first.

Originally posted by Pat Kelley:
Sounds like the secondaries might be lean. I'm not up on spreadbores and don't know how you would richen them.Should be exactly the same as squarebores. Metering plate, or secondary jets. Are there DP spreadbores? If not, then probably plates.

Originally posted by DZAUTO:
Ron,
This is also a tell tale sign of a cam going flat. Thats pretty much the first thing that came to mind for me too