409 Chevy Engine - 481-Inch 409 Stroker

Valve motion is controlled by Manley 22430-16 dual with flat damper springs and titanium retainers. Spring pressure is 205 pounds on the seat, 515 pounds at 0.600-inch lift. Coil bind occurs at 0.740 inch, and the installed height is 1.900 inches. The sexy Scorpion 1.7 ratio aluminum roller rocker arms are box-stock big-block Chevy items that work with lash caps. It all fits under cool cast-aluminum valve covers that came with the engine. Does anybody know who made them?

Dual 750-cfm Edelbrock 1407 carbs rest atop the port-matched L80 aluminum dual-quad intake manifold. The box-stock jetting works fine, but the stock silver metering rod springs are replaced by low-tension purple springs for quicker enrichment. The choke plates have been removed for extra airflow.

The 409 header selection story isn't pretty. Unless you're ready to omit or slice the stamped-steel inner fenders on your '58-up Impala, you're stuck with puny 131/44-inch Tri-Y headers that kill power on a free-breathing stroker like this. Superior modified a set of 2-inch Bassett small-block Chevy 4-into-1 boat headers to accept AVH Technologies 409 header flanges for the dyno test.