power valve makes my 440 ping??

demon seed said

I'd start off by pulling all the plugs and seeing what's going on. Also, are you running the vacuum advance hooked up? If everything looks good but still pinging I'd throw in a 1/2 can of Octane Boost, you may have got some skunky (old) fuel at the last fill and that'll make her knock.

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Try some new fuel or Lucas octane booster. If you continue running with the ping you will damage the main or rod bearings. Check the oil and see if it smells like gas if it does change it right away and check you float settings, if you overfill the bowls excess gas will spill into the cylinders and overcome the piston rings. 8)