Higher oil pressure from thicker oil isn't necessarily a good thing. The higher pressure just means that the oil isn't flowing thru the engine very well. The pressure rise is due to reduced oil flow which isn't necessarily a good thing. The bearings need some oil flow across them to carry away the heat so less flow could be bad.

60 psi with thick oil and a standard pump could be a lot less oil volume than 60 psi with thin oil and a HV pump. People tend to focus on oil pressure since almost everyone has an oil pressure gauge but oil flow is also important.

Very good point Andy.

Yes I agree. Ron

You may believe it or not, but the laws of physics don't change for your beliefs

You do realize that the oil "leaking" from those gaping side-clearances had to come from the oil passage in the journal, pass through the much smaller bearing clearance, then exit via the side clearance? It's a series circuit and the vast majority of the resistance (to fluid flow, just as with electricity) comes from the most restrictive part which is the bearing clearance...

On the heavy duty pump drive... the MP piece I purchased > 10 years ago has worked well for me.

Bill you're crazier than me


He asked for opinions and I gave mine to his situation and the small cost outweighs the cost of a full rebuild. 53psi at 6000 rpm is a little risky to me.

Pick your poison

no disrespect, but i don't agree. my real world experiences say side clearance is a leak.

Side clearance is a clearance just like bearing clearance, the wider the gap ....

Yes, and so is header clearance. Not the point. Please go back and read my post more carefully ... where does the oil (that's escaping from those side clearances) come from? That's right, it's already been through the tightest restriction, the bearing clearance. It is NOT an "independent" leak stealing oil directly from the pressurized galleries and dripping it back to the pan!

So the effect of a wide side clearance is very small (if not absolutely negligible) compared to bearing clearance. As many guys who have put Chevy-width rods on Mopar-width cranks have discovered, with plenty of oil pressure.

Meanwhile, go on believing as you please. No point in trying to teach something to people who already "know".

So you have some identical engines that differ solely in the rod side clearances, and the ones with tighter clearances have more oil pressure? NOTHING is different but that? Same operating temps, oil viscosity, brand, etc. etc. Please provide more info here... If I'm wrong, I'd love to know why other than just claiming "real world experiences". (The plural of "anecdote" is NOT "data").

Also no disrespect intended, of course, but I've met far too many people in my life who know things that just ain't so...

I've got a build pretty much like original poster myself and have similar pressures via stock replacement pump. Decided to run 20-50 as the car is summer weather toy anyway. Pressure now stays at 20 psi min and up to 55 or 60. On the side clearance issue, I've built a bunch of industrial diesels with GOBBS of side clearance from the factory, so it's not a huge pressure loss as ya might think.

Correct. The governing pressure drop is going to be the tightest (smallest area) flow in the system. Once the oil has squeezed through the bearing faces, it is basically open to the internal of the engine. If the side clearance was zero, there would be no flow but you may not necessarily see infinite pressure because of oil flowing through other parts of the engine (the next largest open areas). Once the side clearance is equal to the bearing clearance or greater, it no longer has a significant impact on pressure drop.

By this logic (which I agree with) is 53 psi necessarily a bad thing? From my limited understanding of journal bearings, as long as there is enough oil present to support a hydrodynamic layer, the feed pressure isn't that critical. It's hard to picture a bearing being starved at 53 psi or for that matter 30 psi.

Now you can point your finger and laugh,65 Race Hemi rods and main bearings,standard crank,from 20/50 Kendall GT1 in the early 80's to Brad Penn 20/50 now,65 psi at idle hot and roughly 75 + at 3K,never had a problem,thats how we did things 30 yrs ago.This is what it looked like after 30 yrs when I changed the intake gasket last year.

The general consensus on BB and SB Mopars is 10 lbs of oil pressure for each 1000 RPM, so a motor shifted at 7000 RPM needs to have 70 lbs of pressure at 7000 RPM No matter what weight oil or the oil temps. I got away with 65 lbs of oil pressure shifting at 7000 to 7500 RPm with 5W20 WT oil at 160+ F oil temps in my old pump gas 518 low deck stroker motor with BB Chevy rod journals with .003+ bearing clearnces on the rod bearings and .0035+ on the mains It had from .054 to .035 rod side clearances using a set of 6.800 long BB Chevy type H beam stel rods also, it went against the grain on a lot of the old myths posted on here

I think NASCAR engines run 9000rpm @ 50 psi oil pressures.

Volume peeps, volume.

So I will be happy with my 20lb - 60lb hot

Aren't they running that with a mere half thousandth of bearing clearance and oil as thin as water?

To the OP and everyone else who tried answering without thinking things through: 15psi at idle and 53psi at 00 rpm are very much in line with the old "10psi per thousand rpm" rule of thumb. Why change anything? Your question seems to be based in ignorance. The first responders should have gone there first. Another thing: bearing clearances. I didn't see any bearing clearances that were out of line with what's been suggested here lately.

If you must do anything, add a high volume pump, you can do that from the outside. No need to mess with the spring. No need to disassemble the engine and add a 1/2" pickup. Maybe that's worthwhile on Hemis running 7000rpm for hours, NASCAR 1960s style, but for a street engine it seems to be just another way to screw up a perfectly good block.

IF you have all the money in the world, eliminate the internal pickup and use an external pickup setup, but it is clearly not needed on an engine that just the way it sits has 53psi hot oil pressure at 5000 rpm.

I don't care what oil pump you run, I'd change the pump drive/distributor gear to one that doesn't have a sharp step between the shaft and the hex. That is a stress riser or concentrator. Just from the mechanical design alone it is wrong.

As to the other items that popped up, fluid dynamics is not intuitive. That's why I had to take it twice. The second time through it popped into focus. Then I spent 19 years designing pump systems.

R.