How to determine lifter preload?

[Tim Cucci]

How do you determine lifter pre-load? I have installed a set of reworked heads that have been ported/polished and minor resurface. Valve springs installed and set up at machine shop. CC980 springs,stock cam and lifters and pushrods.
Thanks

 

[Steve Wood]

Here is one method.

http://www.gnttype.org/techarea/engine/pushrod.html

I don't agree with the statement about affecting torque and power at the beginning. If anything, I believe it would be opposite to what is stated. Normally, less preload, to a point, will increase the rpm range of the engine.

Also, a lot of us use Ford rocker shaft shim kits and shim the shaft after milling the heads, etc. Lawrence Conley does it routinely and there is no reason it should be unsatisfactory as long as the adjustment is small.

In your case, You may require a totally different push rod to get into range.