You have to take precision measurements of the bores before you do anything. They need to be measured to the .001" in the top, bottom, and middle. Each bore must be the same front to back and side to side. That's the only way to know if the holes are really round.

Chances are good that you will have slightly oval shaped holes and a ridge around the top.

Only after you have confirmed the bore measurements can you order pistons.

426W pistons are neither cheap nor readily available. Dig around and find prices and part numbers. Be sure to punch the numbers into Amazon to check for better prices.


I'm doing the same thing for my Imperial. Luckily, it has a 440 and the pistons are readily available.