Need advice, have a 65 401 nailhead, stock motor, with 600cfm carter. Checked compression and they are in the 150-170 psi range.Under acceleration, pops thru the carb. Replaced the vacuum advance and set the tming to 10 degrees, still pops. Under no load, with gradual acceleration, no popping. Any ideas on curing this would be appreciated.
did you look inside the distributor cap for carbon tracks? plug wires good, not arcing to each other? no broken valve springs? cam lobes, particularily exhaust lobes not worn down?
1. Do a compression test on all cylinders. It's free, and may lead you in the right direction. 2. Remove both valve covers and start it up; look for any rocker arms that don't seem to be moving as much as the others, signifying a worn cam lobe.
Pull the valve covers and check for wear. The rockers or the rocker shaft could be worn, or there may be a sticky valve. Those rockers are prone to wear and it could be getting a little missaligned and holding up the valve.
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