I built a 305 [.030] with a two plane highrise, f/f tops pistons and 87 corvette alum. heads 1.94 ints./1.50 exhs. 58cc . As I had originally intended to build a 350 and already had a Crane hyd. cam 216 dur. .454 lift 110 L.S. Can anyone say for certain that a dual pattern cam would give the same power and a better idle ? I haven't fired this engine up yet,it's going into an 85 2wd s-blazer with 3.42 gears and a 200 4r trans.

 

why such a small cam? those cams give a nice idle but not as much power as the new design with higher exhuast lift and longer duration. Expecially at higher rpms where the exhuast needs much more time to escape. What kind of idle and power are you looking for? The cam you have is going into a 305 so it should have a nice lopey idle (depending on what idle speed your putting it at).

 

The cam in the 305 is a Crane Energizer 272/454 w/ 110 LS. As I understand it the dual pattern cams have more duration and lift on the exhaust to make up for exhaust port deficiency but if a street engine with good or modified heads and a free flow exhaust, that single pattern cam is a better choice.

 

the dual pattern cams (to my knowledge) will always be better in any application. The single patterns are old technology and have been replaced with the more efficient dual patterns. I have never heard of a single pattern beating out a dual but I could be wrong. It doesn't matter what kind of heads you have, the dual is going to give more horsepower. It doesn't have as much to do with exuast port defficiency as it does the length of time the exhaust needs to escape at higher rpms. A better exhaust system and ported heads will help only so much.