Oil Pressure Issue
 

I need opinion on oil pressure.
When the car starts I have 15 to 20 pounds on start up. As the car runs down the highway I have about 10 to 5 pounds more then the rpm, 3000 rpm 40 psi. After driving a good distance, and the car is up to temp at idle I only have 5 to 6 psi, idling at about 800 to 1,000 rpm. I have had this problem since it was rebuilt, running 10w40. I went to 20w50 castrol and the psi improves to about 10 to 12 psi at idle.
I pulled the transmission and checked to make sure the oil galley plug was installed and it was.

Any help or opinions.

The motor had great oil pressure before it was rebuilt. They did install a new oil pump.

Motor
455 bored .030 over
Kauffman Dport heads, mild porting
Summit HEI
Edelbrock RPM intake and cam
1.65 roller rockers
780 quick fuel carb

Sounds low to me. Couple questions:

What's your bearing clearances?

What kind of gauge?

Where is your gauge taking a reading from, the filter housing or by the distributor?

What kind of oil filter are you using?

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I dont know my clearances. I will check with my engine builder.
Sunpro gauge from the oil filter housing. Engine builder was reading low on his gauge when it was built.
K&N filter.

K&N filters need to be changed more frequently, try an AC and see what your pressure is. Ditch the gauge and get a quality one, like VDU, SW, or Autometer.

If the builder saw it was low, what was his comments?

Definately ask build on clearances, it's starting to sound like they are too loose. And he knows it.

Out of the box pumps usually get only 55 psi or so hot, most shim the relief spring to get more right off the bat. Search here for threads about shimming the pump.

Might want to remove the filter housing and block the bypass, or check the bypass. I'm not a fan of blockign them, but it would be a crutch in a case where the psi is low. It might be hung slightly off the seat, or the tab is bent, allowing it to open at too low a pressure.

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Change the sending unit and/or gage. You cannot rely on readings from these to determine the engine needs to come apart. I've had at least four sending units give false low readings in my years of driving.

The filter is brand new, prob 60 miles on it.
I will check the oil filter bypass, to make sure it is seated correctly.
The gauge is a mechanical gauge, and I had excellent oil pressure on the motor before it was rebuilt.

Builder told me he checked the clearances and everything was inline.

Because you removed the transmission to check the oil gallery plug, I'm assuming you are not talking about the pipe plug hiding underneath the distributor. Have you checked it?

I checked the plug behind the distributor.

Could this problem be caused by a faulty oil pump?

So what were the clearances?

Pumps pretty much work or don't, maybe the check ball is hung. Was the pump disassembled, cleaned, and the pump ball checked before install? Who installed it, you or the builder?

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A new pump was installed when it was rebuilt, and the builder installed it.
I called my builder last night and he was going to go back and see if he still had the information on the clearances. This motor was rebuilt two years ago and oil pressure has always been low.
Builder said that I should be ok, as long as when I stab the throttle the pressure follows, and maintains 10 psi per 1,000 rpm
I am also having to put 6 qts of oil in it, because they were running out of oil pressure on 5 qts. I assume that the oil pump is too far off the floor of the pan.
Motor has less then 1,000 miles on it, its been one thing after another.

This motor was rebuilt before but was done poorly, incorrect cam setup and many other problems, less then 3,000 miles on it before it was rebuilt.

In all honesty I am starting to question my hobby, getting tired of pulling this motor in and out.

You are having to run six quarts because that is the correct amount. The engine holds five and the filter one.

Karl

:usflag:

It should take 6 qts if you change the filter. In some cases, most suggest adding another qt to prevent from sucking the pan dry.

You need to use a different builder is what I'm thinking. It doesn't sound like he knows some of the Pontiac specific requirements.

My guess is there are multiple issues here, one being clearances. If it was low from day one, sorry to say, you should have fought that battle back then.

Let's see what he says about the clearances, don't let up on him for that info. If he can't provide that, then I would say press him on the subject, and maybe even return the engine to him. Mention that you've contacted Pontiac specific builders and they all say the same thing, most likely a clearance issue.

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How quickly will that pressure kill the motor.

You say that the builder saw that it was reading low on his gage right after he rebuilt the engine? If so then it really should have been resolved back then. Pressure on my engine suddenly dropped to levels like you are describing within 1000 miles of installation. I called the builder and he was just as concerned as I was. I pulled it right away, found the cause and shipped it back to him. He took care of everything including the shipping at his cost and was very apologetic. That was two years ago, and absolutely no problems since.

As for the cause- it could be a lot of things but the only way to find out is to pull the engine and open it up. In my case it was actually a pump issue, but probably more likely to be bearing clearances or some sort of assembly problem. I agree with others about using a builder with Pontiac-specific knowledge. There are a lot of local shops out there that claim to have the expertise but haven't touched a Pontiac engine for many years. They might have good intentions but if they don't have the detailed knowledge and you don't either then its a recipe for problems. My builder replaced the pump and also took the time to inspect all the bearings, double-check the valvetrain etc just to be sure that everything else was OK- he did not want it coming back again!

Just to be sure I would try another gage. Or if you have access to a calibrated gage you can also check yours against it on the bench using air pressure.

Maybe never, but at idle, and under modrate to heavy load, there will be excessive bearing wear. You can step up to like straight 40 or 50 and it will help. I think you should go to the VR-1 Valvoline Racing, and probably right the the 50w.

Just to be sure, you should try another gauge. Would remove that as a possibility.

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When the gauge is that low the oil light is kicking on, so I am assuming it is right?

Alot of guys talking clearances and stuff, First thing is, what oil pump are you running, main thing, secondly(by experience) When you had your 455 built are the front oil galleys been removed?? If not i would not be surprised to find it plugged. Thirdly Next to distrib. you will see a plug witch leads straight to the mains. Thats were you want to pick up your pressure from. May need to invest in a fitting or 2 but whats 5.00$ to do it right. You stated new filter but what one??? I can take a picture if you get confused on the oil line but its right next to the distrib. Its usually a square hole in the middle. Hope it helps somewhat, please tell us what pump you have!!

I did not order the pump builder did, I thought it was a melling.