Oil Clearances

[NE57]

Obviously, the oiling system is critical. What I'm getting is that you need to keep the rocker and lifter clearnaces just right so that you don't bleed off too much pressure and/or volume from the main and rod bearings. Correct?

So then, what are the clearance tolerances that people here use, both street and race.

Where/when would you stay at or close to stock clearances and when would you change them?

For example lifter clearance. The Tex Smith book has stock clearance at .0005 to .0015 for the 392. How far off would you have to be before you'd spend the money to bush the lifter bores? Come to think of it, I can't recall reading any specs as to rocker/shaft dimensions, other than advice to have them rebuilt.

Any recipes as far as strategy? If you kept thing tight up top would that allow you to use slightly larger clearances at the crank, and would you want to? A free spinning crank is good but up to what point?

And if you found you were just slightly on the high side of oil clearances here or there, can you/would you compensate at the oil pump? How much pressure is too much pressure? Don't want to drown the cylinder walls, right?

Actually, in a way this recession might help me build a better motor, since I can't just plunk down money in a rush to get it done, I can think more about what exactly to do once consumer start spending again. Retail, sometimes its great and sometimes it sucks.