CORRECT PUSH ROD LENGTH
02-27-2003, 04:15 PM
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CORRECT PUSH ROD LENGTH WHAT IS THE CORRECT PUSH ROD LENGTH WHEN USING THE GM PERFORMANCE PARTS CNC LS6 HEADS AND WHAT IS THE MAX LIFT THE SPRINGS CAN HANDLE?
THANKS, JAMES
THANKS, JAMES
02-27-2003, 04:20 PM
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Re: CORRECT PUSH ROD LENGTH The stock push rods are 7.400. I dont know how much thoes heads are milled but im guessin around 7.350 or 7.370. Use the first ones if theyre milled .050, and the other if its .030
02-27-2003, 05:41 PM
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Re: CORRECT PUSH ROD LENGTH I don't think this is the proper way to determine what length pushrod you need. You also have to take into account the base circle of the cam that you are going to use and how much smaller (or larger, but not likely) it is vs the stock cam.
I measured the stock cam from my 99 LS1 perpendicular to max lift and got 1.552" so radius is .776"
My new cam is 1.496" so radius is .748"
So new cam needs a .028" longer pushrod to keep the same rocker position/preload. However, since my heads are milled .030", that means the pushrod needs to be that much shorter so final size is .002 inch shorter then stock, or 7.398". Since you can't get that, and doesn't matter that close, I need stock length.
This base circle difference gets worse as you go to higher lift cams. The one in my example is a .560" lift.
HTH,
George
I measured the stock cam from my 99 LS1 perpendicular to max lift and got 1.552" so radius is .776"
My new cam is 1.496" so radius is .748"
So new cam needs a .028" longer pushrod to keep the same rocker position/preload. However, since my heads are milled .030", that means the pushrod needs to be that much shorter so final size is .002 inch shorter then stock, or 7.398". Since you can't get that, and doesn't matter that close, I need stock length.
This base circle difference gets worse as you go to higher lift cams. The one in my example is a .560" lift.
HTH,
George
