My current cam, (GMPP HOTCAM), has lfift of .525 with duration of 218/228 @.050. If I were to swap in a cam with the same or slightly less lift but with more duration, would the torque peak move up in the RPM band? (More HP)

The reason I ask is because I'm currently at the max for lift with my current spring/retainer set-up, and I dont want to remove the heads for machining as part of a cam swap. Or is an increase in duration without a corresponding increase in lift a waste of time?

I'm thinking of something in the 232/240 range for .050 duration.

PS It's a hyd roller.

Thanks very much - and Feliz Navidad to all.

Take off the 1.6 rockers it.492 lift. Yes more duration will move the rpm/hp up!!!

You should be able to find a cam with 230-240 dur. and lift below 525. Dur. @ 50 is whats important, not really lift, but if you have heads that flow well its always a good idea to throw as much lift as possible to get every hp you cam.

Yes, your power band would move up but you could still loose overall power. Especially if your heads like the extra lift. Be carefull with the hydraulic roller cams -- without a rev kit you may be limited to just over 6000 RPM (valve float) regardless of the cam specs.

Thanks, guys.

If someone would be willing to run these 2 cams through Desk Top Dyno, I'd much appreciate it. I'd be real curious to see the diff.

.525/.525 218/228 @.050 112 Sep Hyd Roller

.512/.512 230/240 @.050 112 Sep Hyd Roller

Both to 6,000 RPM

383 CI - 9.5:1
GMPP Fast Burn Heads - mildly ported
Perf RPM
650 DP Holley
1 3/4 Full length headers
2 1/2 X-pipe exhaust (if that matters)

Thanks kindly!!

You really need the "advertised duration" numbers to compare sim's. best, imho...

pdq67

Back again, BUT they need to be "real world" numbers, NOT the general "BS" numbers GM has published in the past for their cams..

Sorry about that..

pdq67

Dont worry so much about desk top dyno, figure out the DCR, that will tell you more when choosin a cam...
You could bump the comp up 1 full point too.