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i see on a lot of sites that say you have to lengthen the pushrod holes on the sportsman II's in order to use 1.6 ratio rockers. can anyone be a little more specific? i suppose this is a job for the machine shop only? i like most specs of my cam, im using the Comp cams XE268, .477/.480 lobe speration is 112. duration 234 @.050. but i want to increase the lift with 1.7 ratio rockers in hopes to utilize more of the 200cc on the sportsman II heads i plan to use. i know some people would just tell me to get the next upgrade on the cam but is it really a lot of work to make the 1.7's work just fine on the sportsmans? and by increasing the ratio does that change the length of pushrod i need to use ? im thinking about using summit brand 1.7 roller rockers. this would put me right around .576'' lift on the cam for my 357. what kind of horsepower do you guys think i would be making with this combo? I use the edelbrock airgap rpm manifold, edelbrock 750cfm, 1 5/8'' headers with 2.5'' pipes and H crossover. should put me right in the 400hp brakcet right?
 

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check your flow numbers, do the heads flow well at that lift, or are you defeating yourself? My guess is they probably top out at 500 lift.

k
 

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Even though they top out at .550" you have to keep in mind that the valve will stay open longer above .550" lift. The duration at the maximum fill will be longer with a cam that has too much lift.

Cams are measured @ .050" etc. No one every measures duration @ max lift potential because it changes with each head.

Think about the lift as you would a sine wave. Max lift being RMS. The peak can be too big, but at the same time stay above the RMS value longer. In that case the cam with "too much" lift might make peak power longer.

I have seen things saying that you have to check pushrod clearance with 1.6 rockers on Sportsman IIs. I have a set, and my pushrod slots are round. They are so big that there is no way I could even try to make them bind, no matter how much lift, or what type of rockers.
 
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