Tech Q&A: Frankie Stoddard

April 9, 2001
11:41 AM EDT (1541 GMT)

MARTINSVILLE, Va. -- Frankie Stoddard, crew chief for Jeff Burton's No. 99 CITGO Supergard Ford, stops by to discuss rocker arms.

NASCAR.COM: What is a rocker arm and what is its purpose?

Jeff Burton and Frankie Stoddard keep an eye on the competition.

FRANKIE STODDARD: A rocker arm sits on top of the valve spring area and has a push rod going on the other side of it. It basically runs the motion of the cam up and down throughout the valve train. When the cam rolls over, it opens up the intake valve or the exhaust valve, when the camshaft is telling it to. It's just a rocker on top of a pedestal that either rocks down or up, depending on what the camshaft is telling it to do.

NASCAR.COM: Is a rocker arm a sole unit, or do several parts make up the whole unit?

FRANKIE STODDARD: It's just one sole unit. There's two bolts and a shaft that goes through it with two rocker arms on the shaft that can slide off. You bolt it down. Everybody runs a little different system, but it's just a one-piece unit.

NASCAR.COM: Can a rocker arm be bought in stores, or do race teams manufacture them themselves?

FRANKIE STODDARD: You can buy them at any VSR or any parts store for the most part, but obviously the better quality ones -- Crane Cams, Jessel -- a lot of people run those.

NASCAR.COM: Are rocker arms found on passenger cars?

FRANKIE STODDARD: Yep. Most certainly.

NASCAR.COM: If the rocker arm was damaged during a wreck, how would that affect the racecar?

FRANKIE STODDARD: You'd probably blow a motor. It would shift the valve out of place. And if the valve spring breaks at the same time, you might kick a lifter from the push rod not being in line any more. If the valve spring breaks and breaks the rocker arm, then you'll drop the valve into the cylinder and have terminal problems.