2 lobes on my roller cam are trash (I'll write a separate post on why). I will order a new cam monday afternoon.

My dilemma is should I stay with my present dual pattern or switch to a single pattern.

Current cam: Comp Cams Hydraulic Roller.

224/232 Duration
573/585 Lift
114 Lobe separation

Engine specs: 454, Edelbrock Aluminum Oval port heads. 9.3:1 compression. 1 7/8 headers. True dual exhaust, 2 1/2".

4-speed M20 wide ratio manual. 3.08 rear gears.

Induction is a Holley Fuel Injection with a high rise single plane. 1000 CFM throttle body.

I always took for granted that a dual pattern would work best, but a magazine test got me thinking. They tested a dual pattern against a single pattern. The single pattern had less exhaust duration than the dual. The intake lobes were the same. To their surprise the single pattern made more torque and power. Their thought was that with an efficient exhaust port, the shorter duration trapped more cylinder pressure.

Well, the Edelbrock heads have very good exhaust ports according to the flow tests in Chevy Hi-perf magazine.

Maybe going with a single pattern 224 would be better for me? This cam would then be:

224/224 duration
573/573 lift
114 lobe separation.

One thing I do know is that I will stay with a 114 LS. I absolutely love the wide LS. Nice clean idle, good low speed driveability and good power.

Usage is primarily as a daily driver. Plenty of traffic here in Dallas. A few trips to a drag strip every now and then as well as autox and track days.

Now discuss. :)

 

Saw the same magazine article, pretty interesting.
Guess if you have "modern" heads with good flow, a dual pattern cam isn't required.
I'd really like to know what happened with your roller cam. There was another thread a few days ago about a roller cam that got chewed when a link broke and a lifter went sideways....
I was thinking of putting a roller cam in during the rebuild but I'm beginning to rething that.

 

I've also seen the articles. If you have desk top dyno run a bunch of custom ideas with your heads actual cfm flow numbers. The large dual patterns always come out with lots more power. So when Monty was doing his dyno runs to try and get 700 hp out of 427 cubic inches he and I talk at length about dual pattern cams. He had 3 custom cams made and with 1 7/8th headers and super flowing 18 degree Dart racing heads. The most radical dual pattern with 10 or 12 degrees separation made the most power at every RPM. So when it cam time for my roller cam to be made I went with 6 degrees difference 112 lsa and big lift numbers to keep overlap at a minimum.

In desk top dyno you can juggle the valve events and it gives an overlap figure.

 

I read that CHP article and there is something that bothers me. Yes, both cams had the same advertised duration, but at .050, the dual pattern had 6 degrees more duration. I think that maybe it was slightly too big of a cam for the heads that were used. What really doesn't make sense is that I think I remember the dual pattern gained more from the porting (which favored the exhaust) than the single pattern.

I would have liked to seen two cams of equal duration @.050.

Maybe I'm just looking for excuses of the results since that test disproves many cam theories that I've read from very respected people.