Flathead boggs down

[Ziggster]

There is a “well known” issue with these “new” power valves. It has to do with a radius at the base of the stem. Due to this radius, the gasket cannot sit properly and seal. Looking at the red gasket on the power valve in the left pic, it seems to be “floating” off the base. Certainly, the newer power valve has that infamous radius, and as such, will not seal.