identification · FF-0370

What do the numbers stamped on Offenhauser Flathead heads mean?

They give the cam lift the chamber will clear. Offenhauser heads are stamped on top with 375, 400 or 425. Because the valve rises into the chamber when it opens, a head stamped 375 clears a cam with .375 inch lift. A 425 has a bigger chamber for the taller lift, which puts it in the range for a decent blower head.

Expert

Steve Coppock

Evidence

expert attributed

Component

Offenhauser head stamps

Applicable scope

Offenhauser aluminum heads for the Ford Flathead V8