Pedestal Mount Lifter Preload Question
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Pedestal Mount Lifter Preload Question
I recently built a 400 full roller engine in which I used stock replacement 302 roller lifters. I used a small Comp custom grind since I was building for bottom end grunt. My problem is that I swear I can hear a little lifter noise fairly often as if I do not have enough preload in them. I mocked up and triple measured for my pushrod length using 1 thick shim as a baseline so I had a little room to play in either direction. The Crane shim kit said set the preload between .020" and .060". Long story short, I set them all between .025" and .055". I thought to myself that on an adjustable valvetrain, you take up the clearance and go another 1/2 turn or so, which at 16 or 18 threads per inch on the stud means .055" to .062" of preload in the lifter. So, I guess what I am asking is two questions here. What "range" of preload is proper for a mild, low RPM street engine and is .025" not enough which could be giving me the slight tick sometimes? Thanks ahead of time for helping out and please don't bash me because I built a 335 series engine!
Post Fiend
Joined: Jun 2001
Posts: 5,228
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From: Running Springs CA
Maybe I dont understand your question completely, but I will give it a try. The Ford factory service manual for a 5.0 with hydraulic roller lifters calls for a .091-.151 valve clearance with the lifter collapsed. They recommend using pushrods of different lengths rather than shims to adjust. Of course, the stock valvetrain is non-adjustable.
I remember using preload with Chevy engines and then doing the final adjustment with the valve cover off and the engine running. What a mess!
Jim
I remember using preload with Chevy engines and then doing the final adjustment with the valve cover off and the engine running. What a mess!
Jim
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Jim, if I understand correctly, you are saying that there should be that much clearance between the tip of the rocker arm and the top of the valve stem with the lifter collapsed? So to do the math for how much preload, I would need to know the ratio of the rockers and the total amount of travel of the plunger in the lifter?
Post Fiend
Joined: Jun 2001
Posts: 5,228
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From: Running Springs CA
Yes, just like the clearance measurement for a solid lifter valvetrain. Ford does not specify a preload, only that one measurement, the collapsed lifter clearance. The stock rocker ratio is 1.6 on the roller-equipped 5.0. The only way to measure plunger travel would be with a lifter out of the engine, or by removing a rocker and trying to measure travel from the pushrod tip.
Jim
Jim
