hey i have a 69 nova chevy 350 4 barrel carb running stock cast heads i just adjusted the vavles and it now makes less noise but theres still the loud tick and what i can only describe as a marble rolling around in a tin can.also when i hit the gas ( smash it down ) there car doesnt react fast enough almost sounds like its going to die i checked the plug and plug wires and all checked out ok im running 89 octane and i know the car runs alittle rich i recently replaced the header gaskets thinking i might have had a header leak but im certain its coming from the vavles anybody have any ideas im just about fed up with this motor