I recently read an article about AFR heads and dual pattern cams and I was wondering how accurate this is.

I have a 355 with the following build in a 69 camaro:

Block: Stock 1969 350 / 300hp block bored .30 over (355)
Heads: AFR 195cc heads milled to 64.1cc for 10.325 compression
Intake:Edelbrock RPM Air Gap Dual plane intake
Rockers:Crane Gold Race 1.5 Roller Rockers
Cam: Hydraulic - Comp Cam XE274 (230/236 @50, 487/490 Lift), 110 Lobe Separation 274/286 Advertised
Headers: Hooker Super Competion ceramic coated 1 ¾”. 3” collectors.
Exhaust: 2.25” to 2.5” flow master mufflers to 2.5” tailpipes.(which will soon be 3"in 2.5” out dr. gAs x Pipe)
Tranny:Muncie m20 4spd
Rear End: 4:10 posi traction rear
Rear Tire:26” tall tire
Ignition: MSD Electronic Ignition

The article claims that a dual pattern cam will hurt power when combined with AFR heads due to thier efficient exhaust ports because the cylinder will be overscavenged. Is this true, and if so, how much power do you really loose!

Originally posted by tommyg:

The article claims that a dual pattern cam will hurt power when combined with AFR heads due to thier efficient exhaust ports because the cylinder will be overscavenged. Is this true, and if so, how much power do you really loose! I run a dual pattern in my solid roller equipped 383 with AFR 195's and you couldn't tell it by me. The combo picked up .05 with an exhaust upgrade including Flowmaster 4-2-1 collectors.

An efficient exhaust port is only a small part of the scavenging equation. The physics of the exhaust system create the major effect, coupled with the timing of the cam. Here are some interesting articles on the effects of scavenging and exhaust tuning:
http://www.cafefoundation.org/research.htm
http://www.geocities.com/MotorCity/Track/6992/vizard.html