valve train, oil restrictors

Grumpy

The Grumpy Grease Monkey mechanical engineer.
Staff member
I have Jesel .800 offset intake rockers, Isky EZ X roller lifters, in a big block Mopar, turning 7500, 7800 rev limit. The pushrods are Manton, 7/16 intakes, 1/2 exhausts. I have what is known to be enough pump for my combo in the Mopar camp. I had decent oil pressure running both spraybar oiling in the valve covers and pushrod oiling using Comp cams lifters. When I went to the Isky lifters, oil flow to the pushrods went up to the point my gauge showed a drop in oil pressure to 40 psi (from 65 very hot 20w50) in the traps at 7450 rpm. I blocked the spraybars from receiving oil, but it didn't give me much if any better oil pressure. Bearing clearances are .0032 mains, .0028 to .0030 rods.
For guys running these parts , what ever brand motor, what diameter restrictor are you using in the pushrods? Rpm?

Obviously if the problem appeared just after the swap to the isky roller lifters those lifters are reducing the restriction to oil flow from the oil passages in the lifter gallery, oil pasage routing varies a great deal between different engine familys ,so you might want to use push rods with smaller internal oil passages or oil restrictors in the oil passages feeding the lifter gallery, but in most engines its not oil restrictors that you need, its a bit tighter main and rod bearing clearances, drop your main and rod bearing clearances to the .0025 range and youll have no issues, you can limit the oil flow to the valve train but that results in noticeably less valve train cooling and thats the reason you generally run spray bars, as the extra cooling oil increases durability, your effectively reducing engine durability by reducing the cooling and lubrication of the upper valve train, you don,t want to reduce oil flow you want to control oil flow and direct it to where it does the most good at increasing engine durability.
OIL pressure is a measure of resistance to flow rate, larger bearing clearances offer lower resistance hence the drop in pressure
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