1969 426 Hemi that was recently rebuilt.

With 10W-40 oil and a mechanical pressure gauge, at 180 temp I am seeing around 15-17lbs of oil pressure at idle at approx 800 rpm, rev the motor up to 2000rpm and the pressure quickly rises with the RPM to 55 to 60lbs.
Wondering if that 15lbs at idle is going to be a problem?
Thanks,
Wolf

I'd wonder what the bearing clearances & etc are - hopefully you got build specs.
Mine never had less than about 40 PSI, nor more than 80 PSI with 10W-30 oil.

IMHO, those aren't bad numbers for hot oil. Some people would like to see a little more idle pressure, but 15 to 17 hot is not bad. Certainly not worth a tear down unless there is something else amiss. I would run it.

Now if you can't sleep at night over it, how about a high volume pump or heavier oil? I wouldn't make either change based on what you have given us, but they are possibilities.

I have not been able to get the specs, several people involved to reach the source. Yes, I have also seen higher but I knew it was a high pressure pump. I'm wondering if its a oem pump and that's all it does.

Yea I was thinking going to 20-50 and some Lucas. The motor runs good and nothing is knocking or tapping. I kinda wondered what a factory pump psi idled at and then go from there.

Since this motor is likely just a trick pony for weekend fun I would up the oil. I run 40 weight. Idle is I think 35lbs or 40 lbs. On start up and a bit of RPM over 100 till it get hot then usually has to 10 to 15 lbs per 1000 RPM. I like oil pressure with the proper Pump and Oil pan and I also like quantity in that oil pan. I never run a stock pan the pump could suck it dry at top RPM putting the oil all in the heads. The race motor has all kind of oil pressure pegs the 150 lbs on the gauge has return lines and a dual swing pick up and 14 quarts of oil in that pan. I also has an Actuator that can pump oil in the motor before start up and is activated when the oil drops before a certain number of lbs.

Now getting back to your motor ran into a problem like this with a family members hemi. Rebuilt motor that had 20K on it by a known Alky Funny Car racer. Put it in and low oil pressure like 11 lbs hot at Idle. Shimmed the spring in the pump, was running 40 weight, tried about everything you could thing of. Ended up pull the motor. While on the crane I said let pull the pan before we set it down on it. Pull the pan checked a ton of stuff mostly via site. I see a stamp on the Pan Rail. M 1.5. I tell him the crank is down from the factory and lets pull a bearing right now. Pull a cap and it was standard bearings. So Add 1.5 to the normal stock clearances and that is why we had no oil pressure. I was P@ssed. I had a 10 10 crank and took the motor to him and he pulled the crank and used my crank and he supplied the 10 10 bearing no charge. So so some fine tuning with the oil and if that does not solve things check to see if the thrust bearing is correct and go on from their.

I doubt it will be a problem. Simplest thing you can do is verify it with another gauge. What is the pressure at 1,000 rpm's?

A high pressure pump or spring or shimmed spring will not change the HOT idle pressure. Standard pressure and high pressure pumps will have the same pressure until the lower pressure pumps bypass pressure is reached. Excessive clearance any place the oil goes internally such as bearings, lifters, rockers will lower the idle pressure. If the clearances are causing your issue then a high volume pump(wider rotors) and/or thicker oil may help with idle pressure. The old mopar race manuals used to say minimum oil pressure should be 20psi at idle and then 10 psi per thousand rpm. Some people will disagree with both of those numbers so i'm just throwing them out there as a reference.

According to Wikipedia a top fuel engine starts up cold with 200psi of oil pressure and has 160 to 170psi during the run. YOU DO NOT HAVE A TOP FUEL ENGINE. So you do not need a top fuel oil pump or 50 weight oil.

I get 20lbs at 1000rpm.

Your correct, I tried a shim and did not see any increase over the existing 17lbs pressure at 800 idle.

Never had a Mopar idle at 17lbs, gives me the willies, I may try that high volume pump and see if it helps.

Efforts to connect with the guy who built the motor is not getting results.

What oil pan is on the motor. High Volume Pump could pump the pan dry so be careful.

hi

close to my hemi oil psi .

just add 1 can stp and keep driving !

i drive to and from the track 43 miles one way, pump gas , 11.7 at 118 mph . 3775 lbs

Being recently rebuilt, would it have had a new Melling M-63 oil pump installed? If so remove the "new standard" pink spring and replace it with the older BB oil pump original standard black spring. The last 3 that I have done idle at 25-28 psi hot. If that does not work then you probably do have increased bearing clearance, which is totally understandable for a Hemi.

HTH
Randy

lol that old myth rears it's head again

probably loose clearances with a standard rotor pump. a simple try is straight 30wt rotella vs a multigrade. filters with high bypass springs will reduce pressure a little. long rotor pumps can help low rpm pressure some but the pressure spring in those pumps is pretty stiff. i've done the long rotor pump and standard pressure thing before and it did help low rpm pressure without excessive pressure at higher rpm.

I don't think that is a myth. Wasn't the early recommendations to have a restricted orifice in the channels to the heads to ensure sufficient oil for mains and journals? Hemis do collect a lot of oil in the heads.

On the clearances, what has a larger effect? Crank clearances, or lifter bores? I am experiencing a similar pressure profile, but clearance on crank good, but lifter bores looser.

If you think it is a myth then take a look at how bad the return is of the oil on a stock motor from the Valve Cover to back to the oil pan when you start spinning the motor. If you are going to idle the motor and not use it there will be no problem but then why own a Hemi. If you improve the quantity of oil that goes through the motor then were does the extra volume end up.

Think of how someone would prove this is even a real issue. It would be a pain in the butt. A sight window or sight tube on the side of the pan with a camera mounted in the engine bay, while a willing participant launches the car knowing full well they might starve their bearings and ruin the engine. I suppose someone could do it on a test stand too if they were nice enough and had extra time on their hands.

I don't know about you, but I've never heard of anybody testing this claim, and I think its perfectly reasonable to be skeptical until someone presents some evidence. Trashed bearings by themselves are not good enough. Quite a few things can ruin a bearing.

With all the suggestions here, does anyone have a problem with 60lbs by 2,000RPM hot? I don't. That is plenty. With that much pressure at that engine speed, there is most likely a lot of oil being bypassed as the engine speed increases.

Personally, if the OP has any concerns about a hi performance engine having 'only' 15-17lbs hot idle oil pressure, then the best solution would be to limit the time idling. Or blip the throttle regularly when idling. Changing either the oil viscosity or the oil pump will probably get more idle pressure, but will also bring all the oil pressure up sooner and thereby send even more oil through the bypass. Not something that benefits anything. Just drive the car. Make some small changes if you like, but in my humble opinion you don't have a problem.

And I am surprised that there is any discussion about the possibility of running the sump dry with a high volume pump. The drain back issues are well know on these engines and with the wrong combination of pan, pump, oil and RPM, the oil that should be in the pan can be held up top. We've known that for what..............60 years or so? Not a problem on our wedges, but a very real possibility on our Hemis.

Drain back problems on Hemis is a well known and proven potential problem. And many of us have 'tested' this theory. Having the oil pressure drop off on the big end or at shut down is a real world test. In addition to the factory dash gauge, I have always teed in a 15lbs pressure switch with a warning light in the dash so that I have a heads up that the oil pressure is dropping. I have had to adjust things several times on my Hemis to stop the light from coming on at the end of the track and has probably saved me an engine or two over the years. Now, I keep an accumulator plumbed in when running a stock pan which pretty much puts the issue to bed.