Hydraulic lifter preload...who really checks this?

Kern Dog said
I have a 1990 360 that I'm also working on and it came with a Hughes 1.6 rocker arm set. I'd be okay with just settling with a decent set of stock rocker arms but now I'm wondering if I should be concerned with lifter preload on the 360. How do you adjust that with a stock shaft mounted rocker arm setup? Do you perform a mock up with an adjustable length pushrod and determine the preload with a dial indicator?

If you're considering swapping the hughes rockers for stock stamped rockers, I'd do just as you say measure with an adjustable pushrod tool. I'd check all four corners intake and exhaust. Also check that the tops of all valve stems are level or close to it. Any variation will impact pushrod length for a given amount of lifter preload. Be sure to account for head gasket thickness if the heads aren't final bolted down. I'd lengthen the pushrod tool until there is zero lash, then take it out and measure. Then just add whatever preload amount the lifters need.

You're probably aware already, but with a stock stamped shaft rocker setup, lifter preload cannot be adjusted. You simply need to purchase a set of pushrods that provide the appropriate amount of lifter preload. Once you start decking the block, heads, vary head gasket thickness, shimming rocker shafts, etc., stock pushrods may not cut it. But then again, the lifter preload spec may be wide enough to cover any of those differences in the build. Heck, if you're revertting back to stock shaft rockers on your roller LA motor, I'd imagine stock length pushrods for a roller LA motor would be pretty close to what you need. It's best practice to verify though.

Disclaimer: This is just my hobbiest-level understanding and how I've done it in the past. I'm certainly no expert.