Cam Duration

kurly154

New member
I have 2 motors. One has the dyno 308 260 duration cam. The other has an isky 310 246 duration cam. I've been told that the dyno cam will perform better and pull longer in the upper rpm range then the isky cam. Both motors have 1.3 rockers also. My question is can I turn the motor with the isky cam 8000-9000 rpm? Both are open motors. Motor with isky cam is on meth though. Thanks
 

BradH

New member
I have turned Isky's little 275 lift Black Mamba cam to 8300 which is labeled as a "torque" cam. That thing never stopped making power, I just ran out of track. It had a big carb on it though. There's more to a cam making power where it does than lift and duration. Either of those cams you have will make some high rpm with the right spring pressure. Which one runs better?
 

kurly154

New member
I read on the old bobs that the 308 was 260 duration. I was misinformed. Just checked dyno cam profile sheet and its only 244 duration. Both motors run great. Running the 308 with 26# springs and the isky with the green stripe dual with the inner spring removed.
 

Flash06

New member
Dyno cams 308 and Isky 310 are both 246 duration I think. Both of these cams should have a lot if top end with the 1.3s.
 
The duration is only one part of what makes a cam make HP. Left rate is a big factor. The faster you open the valve, (and the faster you close it, meaning its wide open longer) has a big influence on the cams performance. There are a few other things too.
 

kurly154

New member
Hmm. Good to know. I wasn't sure if it would still make good power turning it 8-9k. Only messed with it on a short 1/5 mile track and turned it 7800. Going to a 1/4 mile track was looking to turn it more but wasn't sure if it would still make power. Thanks guys. Always learning something new
 

clone king

New member
Dyno cams 308 and Isky 310 are both 246 duration I think. Both of these cams should have a lot if top end with the 1.3s.
Yes they do !
The ratio rollers with a split work super awesome with both of these cams.
The split in ratio i refer to is 1.3:1 on the intake. And 1.2:1 on the exhaust.
add .175. billet stroker crank, 2.815 wiseco piston, 14cc head ss vakves, 32
-45. lb springs, have one with a set of 44. Lb springs with 11 lb inners
 
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