358 Small Block Cylinder Head & Rocker Arm Upgrade - A Different World

For our head upgrade, World Products recommended a set of its Motown 23-degree aluminum heads with a 235cc runner. These as-cast heads are all about providing lots of airflow for big-cubic-inch small-blocks, so they were certainly up for the job in our aggressive 358 combo.

Everybody gets kudos when a project goes well, and we have to give a little extra on this one to Manley. World sent us the heads, guideplates, and the proper springs for our solid cam so we could make our dyno day. Manley provided the rest on short notice: +0.100-inch Race Master valves, seals, locators, retainers, and keepers.

We decided to make life easy on ourselves and hauled the heads and all the parts over to BEP Performance in Orange, California, where owner Allan Bessant quickly completed the cylinder head assembly.

Bessant also showed us a neat trick for installing valve seals if you don't want to spring for a special tool. Just push it on with a retainer, and you're good to go. It may seem obvious, but it was news to us.

The valves in these heads are 0.100 inch longer than stock, so we measured for proper pushrod length with a checking tool. The length came out to 7.900 inches; we picked up a set of Manley's one-piece 4130 chrome-moly rods to do the trick.

World sent out the 3/8-inch studs and guideplates we needed-don't forget to use thread sealer on the studs, as they do touch the water jackets.