Greg Fell

iTrader: (9)

I have ARE stage II LS6 castings, that have been milled .035. I have stock length pushrods (7.4). I am going to be using the comp r lifters.

How do I go about measuring pre-load? Do I need a dial indicator?

Steve Bryant

iTrader: (1)

Call the Comp Help line, its free 1-800-999-0853. If you are using your stock rocker arms which are non adjustable, your 7.4" pushrods might be too long by about .035." Depending on your cam lift and the springs that you are using and the rev potential above 6,250 RPM's; I would recommend stiffer push rods with a thicker wall construction. You might need to go to adjustable rocker arms to set the pre loads correctly. The typical setup is to snug down the adjusting nut while turning the pushrod with your fingers until the clearance starts to zero out (resistance to turning with fingers) and then tighten the adjusting nut one half additional turn. Then lock the adjustment nut down with the set screw. You can't do this with the stock non-adjustable rockers.

If your push rods are too long, you will burn valves and you won't get proper compression. That's a loose-loose deal.

Steve

Greg Fell

iTrader: (9)

I have aftermarket pushrods, 7.4". How do I know for sure if the stock pushrods are too long or not?

Steve Burger

iTrader: (33)

You will need to check preload when you install the rockers. I think the 7.4" PR will be too long. With my 5.3 unmilled heads I used a 7.35" PR and a .030 shim.

I see you are just down the road from me.

Greg Fell

iTrader: (9)

ARE is cleaning up my heads as we speak. They maintain that I should use 7.4" pushrods with no shims under the stock rockers. Everything I read about these suggests otherwise! Has anyone used the stock length p-rods with milled heads, and no shims?

Steve Burger, PM me sometime. I'm in Morton a lot!

strokedls1

iTrader: (1)

It depends on the base circle of your cam. A lot of the aftermarket cams have a 30 under base circle. This will cancel out the 30 under milling from the heads and you will be back to a 7.4 push rod. The above description is correct except that instaed of the half turn you torque to 22 ftlb after reaching the zero gap. For comp r's you want to get anywhere from a quarter turn to a half turn to reach the 22ftlb torque. If you have to go much more than that then you will need to place a shim under that rocker arm under the rail. Go through all of them. Some say just check the first two and then do the same for all, but they will all very somewhat so they need to be set up individually. Good luck with it.