Take a look at the heigth of the valves when closed. If #1 is taller then the rest it means the valve is recessed in the seat. I think this is what is happening & someone is adjusting it to compensate for it. If so the head will need to come off & be replaced or rebuilt with a new seat. This can happen with unleaded fuel.


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