[Jerry Clayton]

Mostliquid filled guages have a vent hole that must be opened when installed so that the differential pressure thing doesn't become a factor---of course this also means that the angle that the guage can be mounted is restricted to somewhere with the vent up

On your cars that are running rich in the front cylinders----is your carb/manifold flat/level? If not----with a big cam, the wrong power valve, wrong float setting, the carb will run over into the manifold and will then run on the manifold floor into the front cylinders

Jerry