Hydraulic Lifter Preload on a 350

[#1CutlassSupreme]

Okay, so I'm easily spooked by what I read...and I’ve read a few horror stories about hydraulic lifter cams.

I'm getting closer to turning the key for the first time since rebuild on my 72' Cutlass 350 and I want to make sure I don’t kill the beast. I took the engine out to a machine shop to have it rebuilt and had the machinist install a Crane Powermax Cam with Hydraulic flat tappet lifters. The instructions with the Cam says that it needs a pre-load between .030 - .060. BUT the break in procedure from the shop says to have 0 preload. (I'm sure he's assuming that most stock rebuilds are solid lifters.)

I noticed that stock Olds rocker arms aren’t adjustable and it looks they just tighten down straight to the head. SO…do I have anything to worry about with the lifter preload or is there a way I can make sure that I’m within spec on this? .030 - .060 doesn’t leave a lot of room for error.

I've read that I could basically ruin the cam or bend the rods if there is too much pre-load. And if there isn’t enough pre-load I wouldn’t get enough oil up to the top of the rod and have some serious problems in the valve train.

Any ideas/suggestions/tricks to make sure I'm good on my pre-load?

[Oldsmaniac]

I am not sure what the correct measured preload should be...maybe FAQ's at 442.com will say. Stock valvetrain is not adjustable....slight preload is what you want to keep valvetrain quiet. If preload is too great you can buy shims/small washers that go under rocker arm bridges at head surface. If there is no preload you can buy still (hopefully) adjustable pushrods to preload lifters. You can see what kind of preload you have when the intake manifold is off and rockers bolted down and both valves closed. Look at the lifter and the clip that holds the lifter together. With preload the disc where the pushrod rests will be pushed lower than the wire clip.