In an overhead valve engine, the valves are located in the cylinder head directly above the pistons. This configuration traditionally relies on a camshaft located lower in the engine block, which actuates the valves via a system of lifters, pushrods, and rocker arms. It contrasts with older flathead designs where valves were in the block, and overhead cam designs where the camshaft itself sits in the head.
We need to adjust the valve lash on this old overhead valve small block before it leaves the shop.
While OHV technically applies to overhead cam engines too, mechanics use it specifically to mean a pushrod engine.
Also heard as
- OHV
- pushrod engine
Related terms
Pushrod
A metal rod that transfers motion from the camshaft to the rocker arms in overhead valve engines.
Rocker arm
A pivoting lever in a valvetrain that transfers cam or pushrod motion to open a valve.
Cylinder head
This cast metal component bolts to the top of the engine block to seal the combustion chambers.
Overhead cam
A valvetrain layout where the camshaft is located in the cylinder head above the combustion chamber.