We install a pair of AFR 315cc Fully
CNC Ported Magnum BBC Heads

Words by Darr Hawthorne
Photos by Zak Hawthorne
12/8/04

It was back to JMS Racing Engines in Monrovia as the parts continued to arrive for the re-build of our Project Street F/X Big Block.

These heads were designed to optimize low and mid-lift airflow, while still generating impressive peak figures with a primary operating range of 2500 to 6800 RPM. Mamo emphasized that these cylinder heads maximize the entire flow curve, not just the big peak numbers.

It's really no secret in engine building science that getting air into and out of each cylinder quickly and efficiently is probably the most significant change you can make to your engine. For over thirty years, one of the truly well known names in racing cylinder head technology is SoCal's Air Flow Research in Pacoima, CA.

While talking with Tony Mamo, the principal port designer at Air Flow Research about our engine build, he asked a lot of questions about our camshaft, carburetors, intake manifold and final usage of the 468 cubic inch motor.

Since we will be drag racing and occasionally be driving the altered wheelbase Chevy II on the street to a few local car shows and for Friday night cruises, Tony recommended a pair of AFR 315cc Fully CNC Ported Magnum BBC Heads.

The camshaft grind (CB 4315/4271 R112) from Comp Cams with an advertised valve lift of 0.746, intake duration of 310 and exhaust duration of 315, the AFR heads would retain the Ferrea valves that ship with the 315 CC heads. Mamo felt that with this cam they wanted to upgrade to a Manley Spring and retainer.

The heads are beautiful with extremely smooth runners and significant increase in runner volume over the stock oval port. The new AFR heads include Competition 5-angle Valve Job, 2.250-inch stainless steel intake valves, 1.880-inch stainless steel Exhaust Valve, 1.550-inch OD Roller Dual Valve Spring with dampener and bronze valve seats.

When the new AFR heads were delivered to JMS Racing Engines, just about every guy in the engine shop came out to take a look. Owner Mike Johnson had not seen a set of the 315 CC heads yet and based upon the specs feels that our new combo should dyno strongly at 600+ horsepower.

Before the New Year we will begin our final build and then test on the JMS dyno.

Soft Draggin' [11-24-04] A review of Pro Racing's Drag Sim Software Living in a Balanced World [11-10-04] Why your performance engine needs a high performance balancer Project Street F/X [10-28-04] We install a Dana 60