Help with Flathead vapor lock

[Lynn Eades]

Tim. Yes.
Phillip. 4 to 6.5 psi from your electric pump may be too high and blow petrol sraight through your neede valve. I dont have the specs here, but memory tells me that the mechanical pump delivers about 2.5 to 3 psi.
The delivery pressure of a mechanical pump is solely dictated by the SPRING.
Your fuel pipe shape/ location has a bearing on these problems
Neoprene tipped needle valves work well, if available.
Wear in the push rod etc results in fuel starvation due to loss of volume of fuel delivered.