Scoggin Dickey truck cam??
#23
Staging Lane
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So what you all are saying is that with the stock heads anything pretty much above .550 lift is useless. What if I were using 799's milled .030 and some port and polish work, nothing extreme just smoothing out the roughness of the 799 casting, then would lift above .550 make a difference and how much would it take away from low end?
#27
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Every GM LS head I know of flows great up to .600 even stock. Here are some flow #'s.....
http://www.smokemup.com/tech/ls1.php
http://www.smokemup.com/tech/ls1.php
#28
What Rhino said above. As long as the flow doesn't DECREASE in the valve lift curve you're golden. You just have to worry about ramp rates and appropriate spring rates to control the valvetrain mass. There would still be a benefit to going with a cam with .600" lift at the valve in a head that only flows 1 or 2 cfm more compared to at .550". You've got to think about how much more "area under the lift curve" there would be relative to a cam that had a max lift of .550". If you've got a head that stalls out (or reduces cfm) past a certain lift point, you'd want to stay below that for sure, as that would cause severe issues with flow continuity in the middle of the intake stroke. Biggest thing here I still think would be ensuring your valvetrain components are all matched to handle each other (spring rates, lifter capabilities, rocker positioning on valve tip or clearance issues, pushrod strength relative to loading, and PTV clearance).
A cam with .600 lift is going to spend a certain duration between .550 and .600 which would be max flow for that head. A cam that peaks at .550 will spend 0 time in that range.
And if the lobes have the same profile, then the higher lift cam is going to get to .550 lift sooner.