performance modification · FF-0102

How did early hot rodders turn a four-inch Mercury Flathead crank into a 4 1/8-inch-stroke crank?

They offset-ground the Mercury crank by one eighth inch, moving the journal centerline and reducing the rod journals to two inches. That allowed early two-inch full-floating rods, with custom pistons required for the 4 1/8-inch stroke.

Expert

Steve Coppock

Evidence

expert attributed

Component

crankshaft rod journals, connecting rods, and pistons

Applicable scope

Mercury four-inch-stroke Flathead crank with early two-inch full-floating rods