I,d take a hard look at the plugs. Slow speed & idle while testing can build up some black soot on them & cause that. Also check each one for cracks & loose pocelin. You can crack one putting them in or handling. If not experiment with the timing like the other bolters said.


They say money can't buy happiness. It can buy old Chevy trucks though. Same thing.
1972 Chevy c10 Cheyenne Super
In the Gallery Forum