Hello All, I have a 68 RR with a 440, 850 holley, 391 gears, 3200 stall with a torqueflight. The engine has just been rebuilt and I am seeing 10-12psi at hot idle (900 rpms). When I first start the car, I see roughly 70-75. While driving the car around 3000 rpms, I will see about 50psi. I have been going back and forth with the engine builder, he swears the tolerances were built on the tight side and its not that.

We replaced the stock oil pump with a high volume pump, still seeing low oil pressure. He is now leaning towards the lifters. He installed a Comp cams 21-225-4 cam\lifter kit and believes there is bleed off from the lifters causing the low oil pressure. Does this sounds like a possible issue? If so, what would be a good replacement cam/lifter kit? In addition, I am going to EFI in the near future and he said I may need a more compatible cam?

Any advice would be appreciated.

Thanks,
Don

 

Don -

I think you have enough pressure.
Pretty normal for pressure to be high initially and then drop at idle as the engine heats up.

Archer

 

I would like to see 20 give or take at idle but 10 lbs. per 1000 rpm is norm, and unless you have a seven quart pan put a stock pump on, stock pan stock pump, you can suck the pan dry.

I'd say you have a clearance issue some where.

 

The aftermarket efi available today is infinitely adjustable for any cam.

 

I agree!

 

Have you checked it with a different gauge ? Pull the pan and check the pickup ? could be cracked at the threads /air leak

 

This is a good one I hadn't thought of.

 

Hello guys, thanks for the replies. I do have a 7 qt pan on there and I have a new electric gauge connected to driver side port and a new manual oil test gauge connected to the passenger side port and they both read 10-12psi at idle.

If I left the car running in this manner, what would you expect the life of the motor to be? Am I looking at another rebuild in a few years?

 

IF I can back up the buss just a block or so !!!!!! What weight engine oil did you use?

Nothing strange in the valvetrain ?????

And my 2 cents on the lifters... If you used the recommended lifters for that cam, Thats not the problem, i dont think..

 

My 440 has identical oil pressure numbers. I have always thought the high pressure at startup to be due to the oil being thicker from being cold. Don't worry about it, my engine hasn't been apart in 15 years and has spent much of it's time being beaten senseless. Just make sure and change your oil frequently, those double pumpers dilude the oil quick. I change mine every 750-1000 miles

 

Dam... Thats nuts.... Going to start calling you Top Fuel...lol

 

If I could suggest something...... Try a Wix Oil Filter and a case of 30W or 40W Castrol H.D. engine and see if it looks better....

 

racerhog, that was actually my next step. He put in walmart 10-40 with lucas additive and microgard filter.

Mr4spd, thanks for the reply, that makes me feel a lot better haha

 

If you are running full grove mains then idle pressure will be lower.

 

Word! Not a big deal though, I have a company truck and my driving season is only 7 months anyway. Boils down to two or so oil changes a year, no biggie.

 

Good Point Mr. Stroud......

4Speed..... You need SO-CAL weather... Going to be 90* here tomorrow..
I'm off and going cruising with the Misses.....

 

Hey guys, another thing I want to add.... After the rebuild was complete, I went over to pick up my car and he took me for a test spin. He had the car fishtailing down the street and was just ripping thru the gears. He did this a few times before heading back to his house. Is it possible this caused damage to the motor and the resulting low oil pressure?

 

Cant really say yes or no at this point. Sounds like it has been this way from the get go. Providing that all the parts are solid. oil pump, oil pick up, pick up clearance, on and on... I would guess that the motor has internal clearance issues and is leaking within. Could be a plug got left out or loose, possibly mains have full circle bearings and wrong clearance, Could be to loose on the rods bearing clearance, could be lifters are uncovering the galley, could be cam bearing clearance, Lots of what if's.. Could just be wrong motor oil, oil filter issue, oil pump relief problem..

Bottom line... It's all just guess work, until you open it and start hunting for the gremlin..

Try the oil and filter first and see what you get.. if its still has an issue....
You live with it or go with your gut feeling and dig back into it..
If the guy is a stand up guy, he will understand your concern's....

I will add... That none of my motors ever run lower than 25PSI in my street motors.... That just dosent work for me... but thats me !!!

Just My 2 Cents.....

 

I had a 360 with trashed bearings still had 15-20 psi at hot idle. That is until the crank broke, caused by I think ??? crank flex due to excessive clearances.. That was one of those that sucked the pan dry at 7K on strip in Pomona (2th gear)

 

Yaaa.. Those street legal drags where hard on parts..

 

But it was fun I live 5 minutes away from Pomona It was terrible I would wait all morning to get thru tech & maybe make one run before I had to leave and go to work! (Working Saturdays Sucked ) With street gears 3.23 it was hard the 3.55 worked much better

 

update: changed the oil, added 10-40 valvoline and wix filter. Oil pressure might be a tad better. One thing I noticed though as I was going thru the gears I saw the oil pressure gauge fluctuate between 60-40, it was bouncing around so I let off. This was just on the electric, I have since removed the manual gauge since they were reading pretty much identical. If it really did fluctuate, does this mean the pump may be bad?

 

Cut the old oil filter open. It will tell you all you need to know.

 

I still like this idea, I've had it happen.

 

And the pickup could be too close to the bottom of the oil pan?

 

Could be a bad oil pump. I had the same issue. Went with a miloden pump and cover and now I'm at 80 psi all day long. If I really hammer down lots she will drop to 45/50 psi. I'm using 20/50 oil.

You can also get an adjuster for the oil bypass spring. Highly recommend. The big blocks have an obscure oil path and it takes a bit for the oil to get everywhere. I'd like to see minimum 25 psi when hot. Use a straight 40 or 50 weight oil.

 

I'd go Mildodon and not look back. 10 psi is a little low for my comfy levels.