I'm trying to decide between two engines for a boat. Both are marine engines with marine cams and I want to know how different the idles will be in RPM. Both engines are chevy 350s, 9.5:1 compression and vortec heads.
Cam 1: flat hyd, 202/213 @50, .427/.433 lift, 110LSA, -12* overlap @50
Cam 2: roller hyd, 212/218 @50, .488/.495 lift, 112LSA, -9* overlap @50
Don't worry, I've already machined the vortecs for the extra lift. They both make nearly identical power peaks on desktop dyno, but of course the roller makes about 75 more lb ft at lower RPMs.
-How much higher will my idle have to be with the roller?
-does the type of lifter (and its corresponding ramp speed) have anything to do with idle speed, and if so, what?
-Does advancing or retarding the cam affect idle speed and if so, how?
Cam 1: flat hyd, 202/213 @50, .427/.433 lift, 110LSA, -12* overlap @50
Cam 2: roller hyd, 212/218 @50, .488/.495 lift, 112LSA, -9* overlap @50
Don't worry, I've already machined the vortecs for the extra lift. They both make nearly identical power peaks on desktop dyno, but of course the roller makes about 75 more lb ft at lower RPMs.
-How much higher will my idle have to be with the roller?
-does the type of lifter (and its corresponding ramp speed) have anything to do with idle speed, and if so, what?
-Does advancing or retarding the cam affect idle speed and if so, how?