Custom pushrods, how much stock lifter preload?

AJ/FormS said

Keep in mind that IF the lifters were to pump up, those valves are moving closer to the pistons. Don't let them use up all your PV clearance,lol.
I used to run 1/4 turn, but had to increase it a little, cuz it doesn't take much and things get noisy. So I went to 1/2 turn or so on the rockers. At 28 threads per inch, 1 turn is .036 ..... so I run ~.020 with Hd circlip lifters. This makes them run almost like solids and I don't worry about pump-up.
If you are running .548 lift,then you must be using some HD springs. Some guys here on FABO, have had the unfortunate experience of seeing a pushrod or two punch thru the stamped rocker(s).
Jus saying.

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Sounds about right however you're running a flat-tappet cam, hydraulic roller lifters need different preload to work correctly. I know the stock rockers are borderline but I'm hoping the oil feed through the hollow pushrods will help keep them from punching through; with the stock LA oiling setup it's really difficult for oil to make its way up to the pushrod seat and I have a feeling that has something to do with them failing. More lift = more motion = more need for lubrication...

In my mind if I ran less preload to where the lifters made noise that would be lost motion transferred to the pushrods and rockers; my understanding is the noise comes from the initial ramp of the cam lobe taking up slack in the lifter plunger (and thus the rest of the valvetrain), meaning that much less lift at the valve as some of the lift is being "eaten away" by the lifter plunger. I've found some references where people had better performance AND less noise after increasing the preload on their roller lifters to .060" or more, and running very little preload (like is sometimes done on hydraulic FT cams) made them excessively noisy and reduced the RPM limit.