57thekid,
What do you feel when you lay your hand on the distributor. Can you 'feel' the loud tapping. Using a stethoscope, maybe you can pinpoint the noise. I still can't imagine a aluminum bodied HEI distributor transmitting a loud popping or tapping sound. Let us know what you find.
Was the body of your HEI modified properly to fit into the engine. Isn't the distributor drive gear held on by a roll pin..this wasn't left long and is hitting the cam as it rotates..these are just thoughts if this problem is really a result of the HEI install.
Stuart
