A little help with oil pumps
A little help with oil pumps No, what is in the book does not matter. Ever wonder why some spin rod bearings, and some seem bullet proof?
If you have done as many of these as I, you know that book data may be correct, or not.
I have torn down more than one "large journal SBC (Including LTXs) with .001" rod bearing clearances. Don't spin that sucker 6K.
The standard minimum clearances used by many is .001" per inch diameter of the crank shaft journal. High oil pressure (and certainly not an HV pump) won't make up for a lack of bearing clearances. Too tight, but with high oil pressure will eventually bite you in the butt.
Mine goes 8400 to 8600 (depending on air) in the lights, has no problems with 45 psi.
If you have done as many of these as I, you know that book data may be correct, or not.
I have torn down more than one "large journal SBC (Including LTXs) with .001" rod bearing clearances. Don't spin that sucker 6K.
The standard minimum clearances used by many is .001" per inch diameter of the crank shaft journal. High oil pressure (and certainly not an HV pump) won't make up for a lack of bearing clearances. Too tight, but with high oil pressure will eventually bite you in the butt.
Mine goes 8400 to 8600 (depending on air) in the lights, has no problems with 45 psi.
OK... I agree with everything you’ve posted. I don’t remember what clearances are in the book. It’s the ltx rebuild book that has all the stock tolerances listed. I’ve used it for a couple of engines of mine with a standard/high pressure oil pump and I’ve been good.
Thread Starter
Staging Lane
Joined: Feb 2018
Posts: 94
Likes: 0
From: Bessemer City NC
If it ever did turn over 6k I really would never want to push it over 6200rpm and I wouldn't hold it there very long I'm not looking to **** off the law enforcement because with the exhaust on this thing they're going to hear it coming long before I see them lol I don't feel like having my car taken after putting all this work into it.
A standard volume pump even with the stock spring will do just fine for your needs. I had an LPE setup on my stock shortblock with 6200rpm shift points and had that combo for more than 70,000 miles. For 30,000 miles, I had a solid roller setup with 7200rpm shift points using standard volume/high pressure spring setup, had an unfortunate problem with the lifters/ had to rebuild and when taking apart and the bearings looked immaculate. You’ll be just fine.
A standard volume pump even with the stock spring will do just fine for your needs. I had an LPE setup on my stock shortblock with 6200rpm shift points and had that combo for more than 70,000 miles. For 30,000 miles, I had a solid roller setup with 7200rpm shift points using standard volume/high pressure spring setup, had an unfortunate problem with the lifters/ had to rebuild and when taking apart and the bearings looked immaculate. You’ll be just fine.
And, having one without seeing any issues does not make it a smart move. Some don't seem to get that the original pump is bypassing excess oil back into the pan. They pump at LEAST as much oil is needed. A 60 psi Spring lets that little piston in the cap plate on the pump back up at 60 psi to allow EXCESS oil back into the pan. If the pump was not capable of pumping more oil than the engine needs, the pressure would not go up with a stronger Spring. Understand? Hot, thin oil, loose clearances will often show oil pressure dropping at idle. The bypass is closed then. When it is showing the Spring pressure, say 60 psi, it is pumping excess oil back into the pan. Any time pressure is that high, it is pumping all the oil the bearings can use, and the bypass is allowed to open by the spring, putting excess back into the pan. A high volume pump would simply be pissing more oil back in the pan than the standard pump. Higher oil pressure at a hot idle seems to make the less knowelegable feel better. GM says ten PSI per 1000 RPM is desired. That makes 8psi @ an 800 RPM idle good, right?
Last edited by Ed Wright; Jul 29, 2018 at 11:22 AM.
Thread Starter
Staging Lane
Joined: Feb 2018
Posts: 94
Likes: 0
From: Bessemer City NC
I thank everyone for their input, looks like I'm going to run my stock melling pump but I will also build a bracket to bolt over the drive assembly to make sure it stays put in the whole also for my piece of mind.
Curious to know the answer to man-crush's question as well. Especially with an N20 motor where increased cylinder pressure can be turned on instantly if not using a progressive setup.