Guys,
We all agree that the LS1 and LS6 Stock p-rods are the same, right?
We all agree that LS6 valves are taller, right? By 0.6 mm to be exact or .0236 inch

So if you put a LS6 cam in you need a difference in p-rod length of .0236 inch
So, 7.40 inch + .0236 inch = 7.424 inch

SO, 7.450 inch will be tooooo long and will increase your preload on lifters. The hydraulic lifters are forgiving at the LS6 cam lifts, but do that with a bigger cam and you'll bust some lifters, that i promise.

yeah the factory setup already has a lot of preload i would not want to add anymore.go less if anything.

Yes and you are talking about the difference at one end of the rocker arm. The reason the valve is longer is because the base cirlcle on the LS6 cam is .050 inches smaller. So after everything is taken in with the rocker ration and all, the valve only needed to be .024 inches longer. The pushrod itself is riding on a lifter that is directly riding on the cam. Since the LS6 cam has a .05 inch smaller base circle than a regular ls1 cam a 7.45 inch pushrod will keep it corrected.

The LS6 is not .050 smaller

Do you realise that LS6 02 cam is 204/218 .551/.541 117.5lsa

I think you are going to learn something today. For one why would they use longer valves and stock length push rods if it werent for the cam being a smaller base circle. A stock LS1 cam has a 19.7mm base circle, an 01 LS6 cam has a 19.3mm base circle, and a 02+ LS6 cam has a 19mm base circle.

http://www.idavette.net/hib/02ls6/page2.htm

http://www.sdpc2000.com/catalog/1981...r-Camshaft.htm

Maybe you should call GM and tell them that the LS6 cams do not have a smaller base circle. :)

I did not say that LS6 cam doesn't have a smaller base circle, I haven't measured one but I doubt seriously that it is .050 smaller because of the lifts.
I have a .581 lift cam and the base circle is not even .050 smaller.
As I stated before, I run LS6 valves and they are .6mm taller than my stock LS1's. 0.6 mm = .0236 inch, so with a LS1 cam and LS6 valves I should run 7.375 p-rods (stock gaskets), with my .581 XE-R cam and LS6 valves I run 7.350 p-rods (.045 gasket), my preload is ~.050

Hey red2000z28, PREDATOR-Z is correct in his numbers all along, and your numbers are correct that you copied off of the idavette paged too, but your millimeter to inch conversion and math is a little off. Yes, the 02+ LS6 cam Base Circle is 19mm compared to stock 19.7 LS1 Cam specs but a .7mm difference does not equal .05" its more like .0275" And who do you believe about which pushrod is the correct length? well thats up to you, you know what they say about opinions and a**holes, everyone has one.

Those aren't my calculations, those are from scoggins dickey..

So, what is the diameter of base circle for off the shelf LS1 cams from major vendors?
ie, Futral, TSP, Comp Cams, etc.

They all have different ones. The higher the lift, the smaller

MTI says all of their cams have a stock base circle, and will work with stock length push rods..

You must be kidding right?

https://www.ls2.com/boggs/cam/camanatamy.jpg

base circle (heel): lowest point of the cam lobe in relation to lift; the closed valve position occurs as this portion of the cam lobe turns against the lifter. All valve lash settings are made when each lobe has the base circle (or “heel”) against the lifter (or lash pad on some OHC engines). When a camshaft is being ground, the base circle is the actual part of the lobe that is ground to form lift at the lobe

So like I said, the higher the lift, the smaller the base circle

That simply isn't possible.. The cam still has to fit through the cam bearings. So where does the "extra" lift come from? The base circle, of course! :chug: