blownboat

I have always gone with 1/2 -3/4 of a turn on hydraulic lifters and this should be 20 -60 thousands maximum. I have a set of non adjustable rockers that take almost 2 full turns to torque. This ends up being 95 thousands lifter preload. I was told they would be ok up to 120 thousands, this sounds crazy to me!

Young Performance

Up to .120 is correct. I run that much on certain engines, not all. Most get .060-.090. As I said, it depends on the engine, hp, cam, spring pressures,lifters, etc. Generally speaking, motors with large cams and high spring pressures are the ones that much preload. I don't know what your application is, but it is not out of the question to run that much preload. Hope this helps, Eddie.

blownboat

Thanks Eddie. These are stock gm lifters. So if the cam and valve springs are designed for this, the stock gm lifters wont have a problem? Can you explain the reason why the greater preload?