[HJCHEVY400]

Just wondering why guide plates are needed for pushrods?
Don't know what they actually achieve
Thanks

[BOBCRMAN@aol.com]

On a typical OHV situation where you have a lifter-pushrod-rocker arm situation, there has to be something to locate the rocker arm to valve tip, otherwise the rocker arm will fall to the side and cause problems. To keep the rocker at its proper place several dofferent methods are used. Rail rocker=has raised rails on the rocker arm that set on both sides of the valve tip, thus it cannot move off the valve=early Ford small blocks. late Chevy small blocks. no guide plates needed. Positive rocker location= either the rocker is mounted on a shaft or square locating pin with internal stabilizers. Chrysler , Ford big blocks. Then you get to Chevy, Pontiac and other ball and socket rocker arms. To locate the arm properly, the top of the pushrod is guided with a slot in the head or with a guide plate. The push rod can't move sideways thus the rocker can't move sideways.

[HJCHEVY400]

Does this mean that if the rocker isn't centred exactly on the valve stem, that you can adjust this by moving the guide plates?
Also, will the pushrods eventually wear by contacting the guide plates?

[lluciano77]

There is usually enough play in a guide plate to adjust the rocker so it is centered side to side. I tighten the rocker studs down when they are centered.

Hardened pushrods are always required with guide plates. That reduces the amount of wear to the pushrod. A normal pushrod won't last long with guide plates.