Hemi oil pressure at idle?

A buddy of mine recently purchased a survivor 67 Hemi GTX. He’s concerned about having only 10psi at hot idle, 25+ cruising. I haven’t had anything stock in decades. I told him to enjoy it and not worry. He’s leaning towards an engine rebuild. He did say that the car has a racing history and the engine likely was rebuilt at some point. What are your thoughts?

First thing I would do is try another gauge.
Doug

He did. New gauge, 20-50 VR1.

Generally that would be considered adequate but low, rule of thumb is 10psi per 1000rpm. On performance engines (better clearance controlled assemblies) the pressure will typically be higher. Thicker oil (50 wgt) will increase the pressure but not fix the problem if there is one. What weight oil is in it now?

20-50 VR1

Many years ago I was doing re-ring jobs pretty regularly.
These were low buck deals on high mileage engines.
Most were BB Mopars.
Unless there was a real problem with the crank, they got polished and new bearings.
Several had well over 100k on them when the re-ring job happened.

Those things always had plenty of oil pressure........50-ish going down the road.

I’d pull the oil pump off and apart and check the clearances.
If it’s good, try the HP spring in it.

If that doesn’t help...... there’s probably just a lot of “leaks” in the motor.

I’ve seen big chunks of babbit missing from the cam bearings on old stock engines.

I agree with fast68plymouth, going down the road it should have at least 50lbs. Nice thing is hemi's got the oil pump on the outside, I would take it apart, and check it out. I have had pressure relief valves stick on BBM a time or two, as well.

I assume that the engine is quiet inside or you wouldn't have to ask your question. Do you know if the pump is a standard or high volume? If standard, you might try a new high volume. If it is already a high volume, you might try a new one anyway. I know they are a pain to get to on this, but $50 and a few hours might be worth the effort.

A stronger relief spring won't do anything, the 25 psi pressure never kicks off the one you have now.
Definitely don't use hard throttle until you fix this.
A stuck relief valve wouldn't even do 25.
I suspect loose internal clearances, which means take if down.

I believe in having more oil pressure than I need but that is me. I would take the pump off and look closely at every part of it including the bypass spring, bypass valve and the upper housing where the valve works for damages like grooves and wear marks, replace as needed
I've ran into low oil pressure with hot 5W20Wt in my old pump gas Duster that had a lot of rod and main bearing clearances intentionally , it would idle at 15 to 18 lbs. at 850 RPM in gear with 170F+ oil temps. It would have 20 Lbs. at 1200 RPM and 30+ lbs. at 2000 RPM, 65 Lbs. at WOT above 4500 RPM up to 7500 RPM
That worked well for me

Find some thick green straight 30 or 40w oil and run it. I ran straight 40w in my semi high mileage hemi car.

It was never mentioned if it was stock, rebuilt, ever been apart. I recall oem the had more clearance from new.

Think its 1975, what oil would we use to have good op in a hemi car?

Not the kind of engine to ignore low oil pressure on. I’d start with the oil pump as the others suggested and work from there.

A very common thing in the 70's and 80's. Everything you bought back then was wore out. I changed the oil to 50 weight Valvoline racing oil. If that didn't fix it you put on a high volume pump. I never saw one that these 2 things didn't fix.

I was thinking, id do an oil change and send in a sample to see if there is a lot of bearing material in it then like above and I mentioned go the thick oil.

I do think an oil sample sent in first would be a good starting point before spending money on other things. Why toss parts at it if your bearings are close to being shot?

Can we get a pic of the car????

all the factory street hemi stuff i played with decades ago had a loose wide groove tri-metal main bearing set ms2896p and a cb665p rod bearing that was .001" looser than the cb527p bearing. in stock condition 10-15psi at hot idle wasn't abnormal. some folks would freak out about it and install wedge bearings that were .001" tighter on rods and mains. of course being a survivor with unknown use there could be some wear on the bottom end. also they used a standard rotor pump with a black relief spring.

If it has the stock volume pump you can buy the rebuild kit new rotor/ring assembly and follow SM for rebuild specs. If that is fine and you are running correct oil level, your going to be inside the motor. Anything from a cracked input pickup, bearing clearance, and don't discount lifter bores.

Long shot, pull the bypass valve cap and spring, see if the spring is broke.

Hi guys, I just joined the forum, I'm the guy with the car in question. It's a 66 Satellite Hemi 4 speed, not that it matters for this thread. It's a numbers matching car with less than 1600 miles. It was drag raced in the '60s and maybe early '70s in Alabama, then found its way to Iowa and was stored in a garage for 28 years. Jeff Bobst found it, got it running and had it painted, and sold it to the guy I bought it from. Photo attached for the guy who requested it.
I appreciate all the responses, thanks! One reason Greg started this thread was to see if you all thought the oil pressure was too low for a stock motor, it appears that the consensus is yes, it is too low. The motor is worth more than any car I own, so the low pressure it makes me nervous.
I'm sure the engine has been apart, probably a couple of times. I was told the motor spun a rod bearing at one point. I don't know who worked on it or what's inside of it. It doesn't knock, smoke, or make any weird noises. I'm suspicious that it may have been rebuilt with loose clearances for racing.
I finally got the oil pump out last week, and found it missing an o-ring on the pump drive shaft. Pump rotors looked okay, relief spring was intact, I didn't check the rotor clearances. I have a new high volume Melling oil pump but I couldn't get it on because it wouldn't clear the motor mount. I couldn't get the motor mount out because it wouldn't clear the steering box. At that point I put a new o-ring on the pump drive shaft, put it back together and crossed my fingers. No change..
I guess I'll try to get the high volume pump on again, I'm going to loosen both motor motor mounts and lift the front of the engine with a cherry picker. If the new pump doesn't do the trick, I'll pull the pan. It has a 6 quart pan from another big block on it and there's a decent size dent in the bottom. Once it's apart, I'l plastigauge some rod bearings and see what I've got. As someone stated previously, thicker oil and a high volume oil pump won't really help if there are underlying issues with bearing clearances, lifter bore wear, etc.
Thanks again for all the input.

That dent may have cracked the pickup tube where It’s threaded in the block. If we’re me, I’d drop the pan first. I think u need more oil capacity for a high volume pump. Stock pumps always worked for me in a street car.

from the responses i've read here that nobody is old enough to have had their hands or eyes on the original builds or experienced a factory street hemi.

www.ebay.com/p/8021821548

www.ebay.com/itm/321829849908

Agreed.

This would MY next step.

And IMO go with a straight 30 or 40 wt oil

Is it dangerously low? No. But i wouldn't beat on it hard with it that low either until you know more about the shortblock

Shim the pump...This is always an issue on Hemi engines.

Yes, I agree. Hemi's hold so much oil up top in each rocker cover. Still should be your low oil pressure though.

If someone has installed the 1970/1971 hemi and 440 6 pack 6 quart low profile oil pan you can check the oil pickup to the bottom of oil pan by removing the drain plug and use the stock oil dipstick to see if it will slide under the pickup and pan, if it does sideways, flat and not with it put in the wide way your good.
All the Mopar factory service manuals for those early Hi Po Hemi and Hi Po BB motor recommend installing the oil pickup against the bottom of th eoil pan and as flat as possible
I don't install them against the bottom of the pan but I do use the thin width of the dipstick to make sure it is close and not bottom out flush with the pan
Let us know what you find, you might want to make sure the new high volume oil pump you bought has the black high pressure spring in it and not a stock standard pressure spring in it like some of the new ones have now
If it has the black spring try switching it into current your pump and see if that helps or not
Some racers use to try and run a stock lo po oil pump to gain a little power by reducing the power needed to spin the Hi Po pumps with the high pressure spring in them, NOT ME EVER
I rather use 5W20Wt oil to achieve that result

Questions:
What oil are you using now?
What is the cruise rpm that you have 25 psi?
Does it flat-line at 25 psi, or will it still climb with more rpm? if so at what pressure does it stop climbing?
What is your intended use for the car?

If the car is going to see light duty, and the pressure still climbs above 25 psi with rpm, I would not be overly concerned. I'm not necessarliy saying everything is perfect, but I don't think it needs emergency surgery. Heavier oil and a HV pump are probably reasonable next steps.

The cracked pick-up is not an uncommon occurence and a very credible item for your consideration, IMO.

Nice car by the way.

Do you mean relief spring?

Anyone with experience were the issue was a cracked pickup, did it aerate the oil as an indicator, or undetectable from a look at the dipstick?

[quote=Cab_Burge]
If it has the black spring try switching it into current your pump and see if that helps or not

Cab I have 2 HV melling pumps and both have the plain spring which I thought was the high pressure spring? Good topic for me because I believe my pressure is too high with the HV pump and plain spring. 55 idle hot with 10-30 mobile one. 75 @ 2,000 and gets as high as 95 at higher rpm's. I also have regular melling with pink-red spring and I believe it's too low never gets over 45 hot.

So I'm guessing putting the pink spring in the HV pump would lower it to 45 max too???

I thought the black spring was between the 2 but I can't find one to try. So I'm wondering do I just shim the red spring and if so how much to reach 65psi or cut plain spring to lower pressure and if so how much do I trim?

Problem this is on a hemi and pump must be removed to get to spring and the adjustable product won't fit due to motor mount.




I had a cracked tube and it would lose prime when oil level got below crack, No air bubbles.

Nice car by the way! If you got a standard volume pump in and out, I would think you could get a high volume in there if you took the pump cover off. Put the pump housing and gears in place first, then bolt the cover back onto the pump. Just make sure the o-rings don't fallout of place

Hemis came with the big pump so if it ain’t on there someone changed it out. Dent in wrong pan, first place to look for pickup damage. Every Hemi we had carried 40 psi at idle with those ‘big’ bearings. Also Try another filter. Who knows what’s been done to the engine in those first few years though. I’d have that pan off tonite.
Nice car though, I have a 66 Belvedere Hemi 4 speed trying to get together. Wish you luck and hope it’s an easy fix.

Huh? Hemis had their own pans and pickups but the pump itself was the same as other RB motors. I don’t think Mopar put a HV pump on any production vehicle?

The did have the stronger relief valve spring. But agree not a high volume.

The car is almost 55 years old, and the OP said he thought it had been raced and rebuilt. What's the chances that the OE pump is still on there? But no matter what, I would start with a new high volume pump. Why guess with what is on it and what condition it's in? After changing the pump, the OP can decide if anything needs to be done about too much pressure.

IMHO, messing with the relief spring now is a waste of time because it is basically the same job to mess with the spring as it is to install a new pump and it is unlikely that the spring is the cause of low oil pressure. After finding that there is no o-ring on the shaft, I wouldn't put any more effort into that pump assembly. Just move on.

. ALL of them came with the big pump (it needs the volume because of oil trapped up top). Any and all aftermarket pumps where copy’s of the factory pump. Way back in the day it was called a HEMI pump not high volume (they also came stock with the high pressure spring), you have to be at least 70 to know this stuff, lol, you’re welcome
Also in the early 70s Chrysler sold a ‘kit’ using the ‘HEMI’ rotors and drive with an aluminum spacer to install on a reg pump to make a high volume pump (still got mine if you want a pic)

Yep. All RB’s got the standard pump (relief spring may have varied) from the factory.

hi
my 68 hemi came std pump with hi psi spring !

my current 511 hemi has 60 psi hot crusin !

You buy it new?

Well I might have to eat crow, went back into all my old DC books to double check and the original book said same pump other than black spring. I’ll check my buddies 67 GTX this week to see what it has (original as built). I just remember taking the big pump (all orange) off a blown up 68 Hemi that I picked up to install on my max wedge (in 1974). Won’t be the first time Ive been wrong.

Time is hard on all of us.

x300!!!

Yep brain fade too. Service manual said 25 psi at 500 rpm also so engine is probably ok.

Not an accurate statement. Both Dailey and Wescott pumps only similarity to stock stuff is they bolt to the same place. Otherwise they are wildly different in design(think BBC pump, or roots style rotors in Daileys case).

Thanks to all who have replied, lots of knowledge here!
In reply to various questions, I'm using VR1 20w50 and a K&N filter (I cut open the PH8A that was on it and didn't find any metal, babbit, etc.) It has a 6 quart pan stamped 854, it's blue and has a decent size dent in the bottom. Can't tell you exact RPM at cruise, trying to get my eBay Sun SuperTach II to work correctly. When I put 12V to it the motor stalls, I'll do another thread about that. Anyway, estimated RPM at cruise 3000 give or take, I get just under 30 PSI in 4th at 50 mph when it's fully warm. (It's got 3:54's, you math wizards can work it if you want to). It gets 60 PSI when I start it cold, it gradually drops as it warms up to the point where it only gets 10 PSI at idle. PSI goes up as RPM does, a blip of the throttle gets 25-30. I honestly didn't think to check the bypass spring. Intended use: cruising and car shows, I want it to be a street car that I can drive for 2-3 hours straight, city, highway, whatever.
Very cool idea to install the HV oil pump by taking the cover off to slip it in and then reassemble, I might try that. But- I don't think there's any doubt I need to pull the pan.
I'm taking another car to a show this weekend, then I have travel plans to drive the Natchez trace in a motor home with li'l sis and her husband, may be a couple of weeks 'til I get serious again. I'll let you all know.
Thanks again, you guys are really helpful!

Let me know if you need a hand. I’m car sitting one of our C&C friends. If we can get him to pick up his car, we can install the pump at my house.

Awesome, thanks, I might just do that.

Should of been more specific, cast iron stock stuff.

Many years ago Brother Inlaw had his Hemi Motor rebuilt from his 1969 RT Coronet. Put it in and never had good Oil Pressure. 35-40 max maybe 11 lbs idle. Tried a pump, tried a shim finally pulled the motor took off the pan, I wanted to see if the clearance between the PU and Pan and if it was too close and blocking oil to the pick up. It was fine. Took a look at the pan rail and saw the 1.5M on the rail. I said to him you got the parts list this builder used on the motor. He had put standard Bearings in the motor. The motor from the factory was all read down 1.5. The clearances on the mains were to great. Pulled a 1010 crank out of the garage and off to the builder and told him to pull a main cap and and start measuring. Yes the crank was down and he looked at us with a blank stare. Pulled the crank out and told him to find the sweet spot to putt the crank out and use the 1010 crank and new bearings and rod bolts. Motor has been together since the 80s with out a oil pressure problem. In my street motor that is about 612 HP on start up it read over 100 lbs cold. The race motor is over 100 lbs at RPM. I use 40 weight. So pro mod motors run 200+ lbs and have a 135 shut off but that is a completely different oil system. Stock pans are not big enough if you are going to use it hard. I never run hemi without a 10 or more quart pan on it unless it is some kind of trailer queen restoration.

Every street and NHRA legal stocker 426 Hemi motors I've work on and raced always went faster and made more power with 10W30 than they did with 20W50Wt oil
Shorting up the bypass spring so the motors would have 70 Lbs. pressure with hot oil at 7000 RPM made more power than 80+ lbs. did also with the same oil temps. and RPM
10 lbs. per 1000 RPM with hot oil is a good scale to use
I can remember when the NHRA Comp Eliminator races started using zero weight synthetic oils and changing it after every run to get .0015 ET gain

The pickup screen must be at least 1/4" away from the pan bottom, or it will restrict suction.
3/8" is preferred, but some pans are not deep enough to have enough oil volume above the pickup to keep it submerged no matter what the car does (wheelie, hard braking, spin out). If the oil level in the pan was a foot deep, 3" from the pickup to the pan would be safe.

What is funny about this; is the Service manual does actually say touch the pan. The way the pickup head is built even if touching pan there is access for flow. Most builders do recommend a gap though.

The pickups on Chrysler products were designed to contact the pan to keep them from breaking due to vibration.

You are correct, the pickup basket is designed to provide for flow when the basket is in contact.

Isn’t that’s what that shield on the pickup is for, to touch the pan? Then the screen is up above about the 1/4 that was mentioned.

You are correct.

Ok, long past time for an update. Took more than a while to get to this, but here's what I found. Pulled the pan and the pickup was beat up, crooked corresponding to the dent in the bottom of the (non-original) pan,and had some junk on the screen. Glad I didn't just put a HV oil pump on and cross my fingers, but now suspicious of what else I'd find. Dropped the windage tray and planned to Plastigauge some bearings. I'd heard that #7 rod bearing was a common failure (less oil at the rear of the engine?) so I pulled the cap. Bearing pitted and scored, crank scored enough that it catches on my fingernail. Bummer. Took the Plastigauge back to the parts store. It's gotta come out, now it's a much bigger project. Oh well, I'm disappointed but not surprised. This car has a race history and then sat for 27 years before seeing the light of day again. This is the price for super low miles- neglect is worse than use.
Thanks to everyone who chimed in, once I get it out and pick a machine shop/builder I'll let you know how it goes.

Look on the bright side. You found potential problems before you could see the interior of the engine from the exterior.

Well it's a good thing that you found the problem so you can correct it before you did major damage to the engine. Thanks for updating us on this.

Maybe now you want to consider a stroke or crank, some modern rods, and lightweight pistons?

Someone in the past has made the rod bolt score the crank journal, bad mistake I've seen and heard of guys at the races use a knife wet fine finish stone to remove the high spots off of the ridges from the bolt marks and have no problems with new bearings on those patched up journals If you can feel it now you may want to try that ,if you do that please make sure it is very clean and oiled well before installing the new rod bearings on all the journals

I agree with Cab, I would try to clean up that journal and run it.

You should be able to judge once you get into it, but from the pic, I would try first.

Joe

Appreciate the input, and to Cab's point, you can see the marks on the crank from the rod bolt(s). It's got a race history, and I was told by the guy who owned it after the racer that the motor spun a rod bearing. It's obviously been apart before (the rod caps are ground for balancing, not the oil pan). Likely it was repaired/assembled in a hurry and never corrected.
I nicked the crank with a rod bolt on the first engine I ever built, the machinist (way back, racer from my hometown and former partner of Jon Kaase before Dyno Don fame) said to carefully use a stone to smooth the edges of the crescent-shaped gouge and run it. I did just that and the 289 has been together since 1977 with no related issues.
But- seeing the pits on the bearing makes me think that the oil got acidic while it slept for 27 years and ate the bearings. I didn't pull any other caps but I'd expect to see the same thing. I think the safe play is to tear it down.
Oh yeah, I should have done this long ago but it just occured to me- I have a copy of the Plymouth Service Bulletin # 66-45 dated January 14 1966. Under Engine Lubrication it says Oil Pump Operating Pressure @ 1000 RPM should be 45-65 lbs. So there's the factory spec for 1966 Hemi oil pressure.

Meant to say not the original oil pan.