Case Reed vs. Piston Reed

Dear Ralph:

What is the difference between “case-reed” induction and “piston-reed” induction ? Are there advantages or disadvantages to either one of the methods ?

On a case reed motor the carbs and reed block is mounted down on the crankcase instead of the typical location up on the cylinder. This provides a straighter shot into the cylinder since there is no piston running up and down blocking the passage. Another advantage is in lubricating the rod end and crankshaft a little better. Since the carbs sit so much lower on the motor, tilting it forward is often necessary to get everything to fit in the chassis.

With the piston reed the carbs are mounted higher which makes it easier to package the carbs and the engine in the chassis. The reed block is mounted between the carb and the piston. Performance comparisons show they’re usually pretty close.