This is exactly the profile I have.
7.5 psi at idle is not terrible. A lot of tractors from the 30s-50s only will hold 5psi at idle and they suffer no ill effect. If you have 10 psi for every 1000rpm while the engine is at operating temp you are OK.

My main guess is that your oilpump pickup is not properly submerged. Did you check the clearence with silly putty? You only need a 1/2-1" clearence. I remeber you asking this previous summer about what oil pans work. You wanted to switch pans. If you do not have the right pickup for the pan it will not be submerged in the oil. The thing has to sit in the bottom of the pan. Also, You got 6qts of oil in it right? I have seen chevy guys do this on fords. Dump 5qts in and think its good. It aint.

Shimming the pump is basicly worthless. That is the overpressure bleed off I was telling you to look for on the block a few months ago. I was uncertain if the 300 had one in the block or not. It dosnt is what we decided on.
So all your doing is rasing the spring pressure on the bleedoff so you can build more pressure in the system at higher rpms vs letting that extra oil flow straight into the pan. on an engine that will never see more then 5000 rpm and rarely 4000 this is a waste of time and money. If you had this done on all your pumps I would buy a new pump and dont mess with it.

Try a quart of lucas oil stabalizer or switch to old fashioned straight 50W. The thicker fluid will flow with a higher viscosity and cause the pump to build more pressure to force it out. You live in california if I am right. How often do you see temps below 30F?

Pull your valve cover. Is the oil draining back? if you used a preformance head gasket it may not have the drainback hole just right.

The chances of your oil getting so excedingly hot that it thins out to the level you guys are talking about is low. An oil cooler will help but why not just use a thermometer on freshly drained hot oil to check. If it is over 200 I would suggest an oil cooler but if not your fine. even at 200 your oil should have good viscosity due to the 30W portion of the 10W30 oil.

I would look long and hard at this. You most likely have nothing wrong. A HV pump may actualy give you lower pressure at idle due to its design being for greater volume not pressure.

 

Hey guys--

I wanted to run something by you. My first engine got something in the oil and took out the bearings at 700 miles. At that time I changed oil and filter, rods and mains, and installed a new hv pump.

If there was still a remnant of contaminated oil, maybe a pint, could those contaminants have caused damage to the new pump? Could that have made the pump weak, and be causing low/weak psi?

 

Hey there; glad to see you still plugging, good for you. Anything is possible at this point. What is your oil pressure at start up cold? What is it fully warmed up and idling?(sitting still, no "G" forces acting on oil placement in pan). Are these readings different from when you first fired and ran engine? How do they compare to the first engine? I don't remember if you checked your gauge yet or not. You know once you have checked all the outside things the only thing left is........... yes thats right. Just a suggestion--- maybe make up a story board, like they do on the cop shows on tv, to compare everything,time line.similarities,etc. I'm pulling for you. OBCB

 

The psi now is livable. Hot, and in gear, idling, it is 10 psi. Coming off the freeway, idling in gear, it is 7.5 psi, which is just above the minimum. I can live with it, but for a newly rebuilt engine, I expect more.

When I pulled the old engine it was idling hot at 7.5 psi, and coming off the freeway it was 3 psi. Both were with 30 sae oil.

I'm doubtful that limited exposure to the pollutants could cause the gears to lose pressure. Steel gears! And the thought of pulling the pan for a third time doesn't excite me either!!

First I will do the outside stuff, then the pan and pump, if it comes to that. If I can get it to idle hot off the freeway at 10-12 psi, I'll be happy.

I didn't realize how critical the lifter bores are to oil psi. The backs of the lifters seal the main oil galley, which brings oil to the timing box, the head, and ultimately to the cam. And, it is right off that galley where the psi guage sending unit sits.

 

Oil pumps work with tight clearances,cover to rotor,rotor to case bottom and cavities,ect. Any opening of those clearances would cause decreased oil pressure,so if any abrasive material or metal got run through it,it's a possibility,but you would never know unless you take it apart and check it out.I guess it would depend on how confident you are that anything got to it.These engines routinely run 100's of thousands of miles and with God knows what for oil changes and in very adverse conditions,all this with out oil pump failures.I don't know what to tell you,I guess I would be wrestling with that choice myself.Another oil pump isn't costly,it's all the work to put one in,but if it is scored inside,then it would be worth it,if it isn't the problem,then you just spun your wheels again.

 

Hi again. I thought my lot in life was the only one like this. Enough of this. What is your cold start up pressure? This coupled with the hot pressure will be an indicater of clearances inside your engine. My manuals show stock oil pressure to be between 35 and 60 psi. I assume this is warm at rated rpm with manufaftures recomended oil wt.(30 wt. ?) this coupled with the "Old rule of thumb" 10 lbs for every 1000 rpm works out. "MINIMUM" 35 psi at rated rpm. "Rule of thumb"------ "BIG THUMB". Like you, I would expect alot more pressure from a new "TIGHT" engine. 50 to 60 at cold start up, 40 + at hot idle. Do you remember the clearances from your build? Plasti-gauge bearing clearances, rods and mains. Were special bearings used? The small block ch#@! guys have narrow shells for large fillet cranks, the controlled leak is huge here, hence high flow pumps. When you get to removing your existing pump you could rig up a test for it out side of the engine with some pipe fittings, a valve, a piece of plate, your drill and a gauge. Simple ha ha ha.OBCB

 

Did you carry over your lifters?You might,just for kicks,mic some of the stock lifters,then call the place your new ones were made and find out what size they use for their spec.Just a shot in the dark,but what are the chances of 2 blocks having worn lifter bores? You should not need any oil viscosity additive,it should be right with your regular oil.I use 10w40 Castrol year around here in Michigan.I like that top number,and even with 40 as top,if it gets hot enough,it will thin.That's why I think oil temperature is important.What is your hot idle rpm?When it's hot and doing 7.5# take her up a 100 rpm and see if you increase to 10+,if that's the case,raise your idle just a fuzz.On automatics,I used to set mine to where it wouldn't crawl in gear and called it good,I never liked extremely low idles,I don't think it's good for the engine.If it's under 1000rpm,that's good enough for me.

 

Flip--

Thanks for the suggestions. I am waiting for the rain to pass before I pull it apart and make some minor changes.

The psi is livable, but with a new engine it should just be more. There is little room for wear. I want to get 15 psi at idle, and I will.

.** A HV pump may actualy give you lower pressure at idle due to its design being for greater volume not pressure. ** That doesn't quite make sense. Whether the OE gear, or one that is 25% taller, they are being spun by the engine, the dist. gear, at the same speed regardless of speed. More volume could never produce less psi at idle.

 

Hey guys--

I'm waiting for the rain to pass, then I'm going to make some changes: bleed the guage line, install a second guage on the block to compare, change the oil to 15/40 since I live in S. Cal., and go to wix filter.

If that doesn't get me where I want to be, then I will think about r&r'ing the pump. First I want to take apart the oe one from the first engine and measure the clearances. That should give me an idea of the state of my current pump, that may of had contaminants run through it too.

I'm really looking forward to pulling the pan ...and radiator ...again.

 

The big difference in the HV pump is deeper cavities and taller rotors,so it moves more oil through it per revolution,the pressure should be the same or slightly higher because of the amount it's trying to push.It would never be lower unless it scored or prematurely worn inside.Clearance between the rotors and the cover are very critical to gear or rotor type pumps.Oil viscosity is directly connected to pressure,that is why they push high pressure when they are cold and why just a few degrees too hot will drop pressure like a rock.Of course internal engine clearances really affect pressure also,there has to be enough resistance there to be able to build pressure,even finish on varius bearing surfaces can affect pressure,the slicker it is,the easier the oil moves.Years ago,I put in a, then new, Teflon oil additive to my oil in an Opel Kadet (great little car) and instantly lost 5 psi,and never got it back,because the Teflon reduced the resistance of the oil flowing through the bearings.That's one of the reasons I'm against oil additives,the engines weren't designed to need it,so unless it's a last ditch effert on a tired engine,I avoid it.I know I have said most of this before,but if anyone reads this post and it saves them adding crap to a good engine,then it bears repeating.F-250,I hope you find that bug,good luck.

 

Not saying that it is going to be lower but you can only get so much oil through a stock pickup. On the discharge side of the pump busters ideas hold true. Idealy you need a larger diameter pickup to allow for the increase in volume being moved. There are a lot of neat books on the theories of hydraulics. I have to know some of them as I work in a factory that has somthing on the order of 800 pumps.

 

Hey buddy, a thought occured to me (rare occurence) did you say that you carried forward the HV oil pump? Did you tell your machinest? Your friend/ builder? If so, did no one suggest opening it up to inspect/clean, before installation.Your frustration can be felt here and we are all with you, but as with any diagnosis a complete picture must be painted. At this stage massive work/ money/ frustration has been expended. With no resolution. It;s time to go to the foundation and re,re,recheck everything. I know it's very easy for me/us to sit here and tell/suggest what you should do. If I was there I would be right next to you helping,sorry I'm not. Please don't misunderstand, this is not a bash /put down/ or any disrespect. With so many unknowns it is necessary to start eliminating them. Just like enemies, get rid of them one at a time.


PS, forgive the icons, I'm still learning how to play with them. OBCB

 

It's all good, Cowboy. The pump was reused. It had about 1,300 miles on it. We opened, cleaned, and inspected it. It showed no chaffing, wear of any kind. So, I put it on the new engine.

 

It sounded like on the second go, that you were on your game. Glad to hear it. Buy the way, what is your cold start up oil pressure, cruising pressure? OBCB

 

In the morning I have 52 psi. When fully hot at idle I have 10 psi. Coming off the freeway to a stop I have 7.5 psi at idle.