Lifter Bore Measurements

Just to get a concept of how much flow area is around the lifters bores relative to other known critical areas, I ran some numbers for the exit flow area around the lifters and around the main bearings. Actually flow will vary from these numbers, and depends on a lot of factors like the actual pressure at each point; so this is just for a basic appreciation.

There are a lot of lifters versus bearings so their smaller hole sizes add up. These numbers assume even wear around the lifter bore, which I don't think is the case. So real lifter bore wear will presumably be less pronounced for flow area increase.

Numbers are for different clearances up to .004". Factory nominal clearances. were .001" for both main bearing and lifter-to-bore clearances.

.001" Mains: .079 sq in - Lifters: .091 sq in
.002" Mains: .157 sq in - Lifters: .182 sq in
.003" Mains: .236 sq in - Lifters: .273 sq in
.004" Mains: .314 sq in - Lifters: .364 sq in

You can see how huge the flow area around the lifters would have been for Blucuda413's standard lifters in the .008" oversize lifter bores LOL! Or how much the flow areas increase with big main clearances. At some point, the oils pump's flow is gonna be approached at lower RPM's and the back-pressure is gonna drop like a rock.