If you talk to the camshaft/lifter manufacturers, none of them will recommend any restriction to their lifters. The maximum amount of oil that can be put in their lifters provide one less excuse when they fail one or more of them. But the reality is a Pontiac V-8 puts much, much more oil to the valvetrain than what is needed at the expense of adequate oil to the main and rod bearings. This is especially true in 3.25" crankshafts and high RPM's. Excessive lifter to bore clearance, excessive connecting rod side clearance, and bearing clearance make the situation worse. Lots and lots of opinions on proper oil pressure, 60 vs 80 lb. pump and lifter restrictions or pushrod restrictions. You will have to make your own decision of course. I can tell you I have never built a solid roller Pontiac engine with a larger than .045" restriction at each lifter bore or bushing. For high RPM race engines, over 7000 RPM, .030" is plenty large enough with an 80 lb. pump and 10W-30 oil. You would be amazed how much oil can find it's way through 16- .030" holes. The top end is flooded. Have been using pressure lubed axles for years, both needle and bushing style. I should mention I have not used the Howards lifters in a Pontiac, but have in other engine platforms. The Howards lifters I have used were all made by Morel. I have used Crane, Crower, and Comp lifters in the Pontiacs.
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