valve lash

[sext7366]

I read that setting the correct valve lash is a good idea in a tech article because it helps to add power. just curious how to do this and how important it really is.  The page in my stock service manual is missing for some reason.

[Runner]

do you have adjustable valve train? like pushtubes or rocker arms?

[1970440RT]

Back when I did my first Mopar Big block, I went crazy looking for the correct lash settings and how to do it.  Chevy guys looked at me weird, Mopar guys laughed.  Using stock rockers, shafts, and pushrods, there is no setting.  ( on 383, 400, and 440 ) just torque down the shafts and you're done.

[Runner]

with stock valve train you could get a checking pushrod and then get your lash correct, then order custom pushrods once you knew the correct length.    .    on big hydrolic cams(all cams for that matter) they dont have more lift on the lobe, they take off the base circle, this will sometimes require a custom pushtube.

[Chryco Psycho]

by using shorter pushrods & limiting lifter preload it limits lifter pump up which can hold the valve open at high rpm
you would need to take a careful measurement of the piston depth in the lifters & have a shorter pushrod made with approx .020 lifter preload
As Runner mentioned high lift cams have a lower base circle not a higher lobe so this can cause slack int he valve train & require longer pushrods & should be checked whenever installing a larger cam