[roadrash9r]

With the ls6 cam having a smaller base circle and GM having to use longer valve stems to get the 550 lift. Would you have to use shorter pushrods with an aftermarket cam? All the cams I have been looking at are for ls1s and ls6s but that cant be true because when swapping an ls6 cam into an ls1 you need longer pushrods or the ls6 valves. What this looks like is if you use an aftermarket cam in the ls6 with 560 lift you probably have around 600 lift with the longer valve stems and 7.4 pushrods. Or you are loading the crap out of your lifters with non adjustable rocker arms. Please someone tell me IM dead wrong!!!! I just ordered stock length pushrods!!! thanks

Sorry I should have probably put this in pit road.

 

[Black_Magic]

I installed LS6 CAM in my LS1 and pushrods were .050 longer (7.450 vs 7.400) BUT you can go without using the longer ones as they are only 50 - 1000's longer. I went with the Manley Harded push rods.

I think you are ok going with stock length.

Here is write up on the kit I used.

=================

LS6 Z06 Camshaft Kit, for 1999-02 LS1 Engines

The SDPC LS6 Camshaft Kit makes your cam swap easy and painless. We include the GM LS6 camshaft (204/218 dur @ 0.050 and 0.550/0.550 lift), SD1423 valve spring kit with titanium retainers, Manley pushrods (7.450), Rollmaster double roller timing set plus all necessary gasket and seals and a new balancer bolt.

Note: The pushrods used in this kit are intended for use with LS1 heads only, Different length needed for LS6 heads. The block and LS1 heads must have factory deck surfaces. If the heads or blocks have been milled, the pushrods will be too long. If your heads or block have been modified, please call for assistance

========================

George

 

[dailydriver]

Your stockers should be fine. Check with the cam grinder and buy and adjustable push rod checker to be double dog sure.

My cam has a 559/568 lift and I used at Comp Cams recommendation, their Hi-tech 7.400's with GM 1.7's and it worked out just great. This is with AFR 205's and Comp Cams roller magnum hydrallic lifters.

Alot depends upon your heads, gasket thickness and ultimately, P/V clearance. With a mild cam you should be fine.

JMHO

 

[jub jub]

One thing you can do once you get your cam in is to turn the engine over until #1 cylinder in on TDC and both lifters will be on the base circle of the cam. Install the pushrods and rockers and tighten the rockers until they make contact with the pushrods and will just barely turn. This is zero lash. Now tighten the rocker arms down and count the turns. You should have around a turn to a turn and a half of preload. Then tighten to 22 ft lbs.

Hope this helps.

 

[roadrash9r]

Thanks all. Thats a relief. Actually I called comp cams and asked what pushrods I would need and the answer was stock. They said most if not all of LS series aftermarket cams are the same as the stock ls6 in regards to the smaller base circle. So all you ls1 guys running aftermarket High lift cams might want to check your lash!!!!! For those who dont know, the ls6 heads have longer valve stems to make up for this while still running a 7.4 pushrod.

 

[ss2z06]

stock 02 and up ls6 cars use 7.35 pr's stock. FYI
-matt

 

[Jim Lembo]

stock 02 and up ls6 cars use 7.35 pr's stock. FYI
-matt

Matt,
I recently did a H/C swap on my '03 Z, the stock pushrod length is 7.400 on the LS6. My heads are angle milled for 11.2
C/R, and I used Comp Hardened rods that are 7.350 specifically to match the milled heads.
Jim

 

[ss2z06]

Maybe only in 02 then. My stock one's were 7.35. I even confirmed that with lou at lg. I had to go to the 7.4's when i put on the un milled afr's.

 

[22655TD]

The length you use depends on the dase circle of the cam. Comp R lifters are very sensitive to preload. You need to measure the set up with a push tube gauge. Comp cams told me they only recommend adjustable rockers with Comp R lifters and you need the better lifters if you run double springs and a high lift cam.

 

[roadrash9r]

The stock length for z06 pushrods is 7.4. The way GM made up for the smaller base circle cam is by making the valves longer. This kept the rockers centered on the valve stem tips. As for aftermarket cams they should all be the same base circle as the z06 cam or the lobes would not fit through the cam bearings during install or removal. This is the exact reason GM ground the 02+ z06 cam on a smaller base circle!! Just my .02

 

[roadrash9r]

ss2z06 Your information is incorrect. Think about it, if the base circle of the cam is smaller than you would need longer pushrods for the same head, probably 7.45 to make up for the extra space. If you used 7.35 there would be a massive lash problem or the rockers would run from tip to tip on the valve stem. The ls1(large base circle) and the ls6(small base circle) use 7.4. the ls6 uses longer valves to make up.

 

[Flareside]

You guys are going about this the right way. Install the cam, mock up the engine, and check your lifter preload. Don't assume that 7.400" is right, because more often than not it will be too short to get lifter preload back to the stock dimension. You will be light on preload, you'll get more valvetrain noise, and you'll be running a much heavier lifter because of all the extra oil inside it (earlier valve float). I had an LS6 cam, and it measured .029" smaller than the LS1 on the base circle. I've also have a Comp XER that was .040 smaller, and my current LPE cam is .050" smaller. Don't assume that there's a standard for aftermarket cams, because there isn't. Because most of the LSx cam lobes are already as tall as will fit through the cam journals, the only dimension that the cam grinders have to play with is the base circle, so that's how they change the lobe lift. Most LSx engines have .060" or more preload stock.

FYI, it's impossible to accurately recreate valvetrain geometry without taking the eventual lifter preload into account. If you use soft "checker" springs and adjustable pushrods, you won't get any preload while you're checking, and if you use normal valve springs and an empty lifter, you'll get lifter preload, but the lifter plunger will sink as soon as you start lifting the valve off the seat, and it will really sink as pressure builds when the cam goes over the nose. Incorrect results again. IMO, the safest thing is to take good measurements and get the preload back to where it should be. Take notes on changes in valve length, milling, gasket thickness, pushrod length, and stock lifter preload.

 

[roadrash9r]

flareside isnt there alot of "play" in hydraulic lifters? If it is suppose to have an .080 stock lifter preload, wouldnt you say you would have no problems at .050. Its common to think that you will always loose a little lift to a hydraulic lifters due to the rebound inside the lifter. Now way to tight and you have a solid roller and way to loose and you have the trampoline effect. but I would guess .030 - .100 preload would work, maybe not perfect but like you said there is no consistent or "DEAD" acurate way to check your lifter preload.