My 1964 Skylark convertible has a 300 WildCat engine and hgas a lifter tap that comes and goes, I started using straight 50 weight oil and the tap comes less often but still comes, how can I fix this?

if you stop running regular gas in the vehicle and start running super with the higher octane reading the tap should go away. I think it may have something to due with aluminum parts of the engine but I had a 300 with the same problem and found the 'premium' trick worked well?

I've been told, years back, the higher octane acted as some kind of a lubricant in the gas, for the engine. I started using the more expensive fuel and the noise was gone? Expensive fix but worth it with these older vehicles.

your problem is the oil pump needs to be rebuilt. It is part of the block. The oil pump is not separate. You can only buy a rebuilt kit.