Edelbrock Aluminum Heads Our own flow testing and DMR's experience showed us that the off-the-shelf Edelbrock aluminum Performer RPM heads flow about the same as a set of factory iron C heads. This limited flow is partly due to the requirement that the ports (especially the exhaust) remain in their stock locations. We wanted to improve on the intake flow slightly without spending big bucks for CNC porting, so we tried the classic 30-degree back-cut trick on the Edelbrock valves, which netted a minor flow improvement. The Edelbrock heads measure 77 cc and combined with the 15cc dished KB pistons create a 10.2:1 static compression. The Edelbrock Performer RPM aluminum head flows 240 cfm at 0.500-inch lift and has a decent exhaust-to-intake ratio. Dick Miller Racing offers several porting options should you wish to enhance the power potential with additional flow. The Edelbrock Performer RPM aluminum head flows 240 cfm at 0.500-inch lift and has a decen The Edelbrock heads also require a set of aftermarket aluminum rocker arms, so we chose one of Comp's new Ultra-Gold 1.6:1 rockers that are a little more affordable. The Edelbrock heads also use 3/8-inch pushrod guideplates, which dictate 3/8-inch Comp pushrods. The Edelbrock heads also require a set of aftermarket aluminum rocker arms, so we chose on Flow Chart Edelbrock Performer RPM Olds Aluminum Head 2.07/1.68-inch valves (PN 60519 complete) 77cc chamber 188cc port VALVE LIFT INTAKE EXHAUST EXHAUST TO INTAKE RESULT OPEN WITH PIPE INTAKE 30-DEGREE BC (CFM) (CFM) (CFM) PERCENT (CFM) 0.050 34 25 73 -- -- 0.100 70 53 76 70 -- 0.200 137 95 69 144 + 7 0.300 195 132 67 206 +11 0.400 234 168 72 246 +12 0.500 240 185 77 237 - 3 0.600 245 194 79 239 - 6 A simple 30-degree back-cut on the Edelbrock intake valves was worth as much as 12 cfm at 0.400-inch valve lift. The production 455 head we tested at 0.400-inch valve lift flowed only 190 cfm. Our modified Edelbrock's amazing 56-cfm flow improvement at 0.400-inch valve lift is a 29 percent gain over the stock heads. Cam Specs COMP XE-268-H-10 DURATION DURATION LIFT LOBE DEGREES DEGREES (INCHES) SEPARATION (ADVERTISED) (AT 0.050) Intake 268 224 0.485 110 Exhaust 280 230 0.490 Test Day Edelbrock agreed to help us with the dyno testing, and Edelbrock dyno veteran Curt Hooker bolted our 461ci Rocket to the company's SuperFlow dyno. Before firing the engine, we pressure-lubed it with a homemade tool that really was nothing more than a 6-inch-long Allen bolt. The bolt head is used to spin the hex drive oil pump driveshaft. After properly timing the Performance Distributor D.U.I. HEI distributor, Hooker carefully broke in the Comp flat-tappet camshaft for roughly 20 minutes using Royal Purple's 10W-30 break-in oil. « | 1 | 2 | 3 | 4 | » | View Full Article By Jeff Smith Enjoyed this Post? Subscribe to our RSS Feed, or use your favorite social media to recommend us to friends and colleagues!