[1qwerty]

I have purchased my first pontiac a '70 Firebird w/455
Engine reportedly was gone through about 800 miles ago .
I have low oil pressure 10psi or less at hot idle 30 psi at 3000 rpm
I have changed the oil and tested it on a Snap On gauge same results ,no real answers from the seller.I was wondering what the chances are a galley plug came out. If I pull the timing cover and look if I have to pull the pan the motor is coming out, anyone know of a good machine shop in Houston or within a couple of hundred miles
Thanks JWB

[steve25]

If a galley plug cam out I do not think that the pump could hold 30 psi at 3K rpm.

My bet is the oil pump check ball is being kept unseated due to ingesting some crap .

It’s time to pull the pan because even if the issue was due to a popped out galley plug you would want to inspect the bearings, or at least I would.

The rod in cylinder #2 gets oiled last, so that’s the first bearing to put your eyes on.

[Lee]

I use Jeff @ Westside Machine & Performance for my machine work.

I also sent you a message (upper right hand corner of the page).

[bdk1976]

Where are you pulling your pressure readings from? Are you certain your gauge is correct? What weight of oil are you using?

I'm not sure the oil pressure in my stockish 455 is THAT much better? Is there anything other than your gauge indicating a problem? Lifter clatter or other noises?

[1qwerty]

No unusual noises
Gauge in the car and the snap on tester where the same
20/50 amsoil high zinc

[1qwerty]

The old oil looked fine no glitter

[1qwerty]

One thing that bothered me is the dakota gauge is electric the snap on is mechanical
Got alot of fluttering on the mechanical (air maybe?)

[1qwerty]

I apologize for all the posts
One last thing the oil filter was maybe half full or less and I pulled it off about 5-10 minutes after shut down and noticed no bubbles
Thanks again for the help

[Tim Corcoran]

I had a 455 that had about 6psi at hot idle and drove that car for thousands of miles and hundreds of 10 second 1/4 mile runs like that. You may not have a problem at all. 10 PSI per 1,000 RPM is good enough. No unusual noises and if the oil comes out clean I'd say drive it. Now if the oil pressure changes, drops, then I would worry

[jhein]

So you have 30 psi at 3K, is that your max psi? What is it at 4k and 5k?

It sounds like you're saying it runs OK, and has no suspicious noises. So maybe before doing anything drastic, live with it, while monitoring closely and send in a oil sample for analysis.

[steve25]

The pulsing seen with a mechanical gauge is clear evidence of the pumps check ball being unseated or the pick up tube has come out of the pump body.

If you live with it as others have suggested ( of course it's not there money involved) then you will likely have to take the drastic action of having the car towed home and opening up your wallet for a expensive rebuild, that is if a Rod does not fail and blow out one side of your block.

[1qwerty]

I would not run the car as is ,oil pressure is way too low .I have been working on engines and equipment for a long time
(40+years) I would not be comfortable running it.
I was just looking to try what I can and then pull the motor if nothing fixed it
All replies appreciated

[steve25]

Well if it comes down to having to pull the motor then before that and for its & giggles pull the timing cover and take a look at the two front oil galley plugs .

[1qwerty]

That is the plan ,just not betting on it being that simple

[steve25]

Unfortunately I agree!

[chiphead]

Cut the oil filter open first. If there is no metal in the filter pleats, this is a good sign. Usually if an engine is going away, the shredded bearing material gets trapped in the oil filter pleats. I cut my filters, and have a tool for doing it, kind of looks like a big can opener.

No metal in filter means either the checkball in the pump is stuck or maybe the engine was built with very loose clearances. I had this happen with my current 400. I had done a cam change, and then shortly after the oil pressure was like 10 PSI at idle, no higher than 35 PSI at 2500 RPM cruise. I guessed the ball was hung up, so I gave the engine 2 or 3 good revvs and shut it off. The next time, magically it had the proper oil pressure again. I then cut the filter open and found a wadded up piece of masking tape. I had used blue painters tape as a pattern to clearance the valley pan to fit the intake. A piece of blue masking tape got hung up in the ball and bled off a bunch of oil pressure. A few revvs blew the tape from under the ball and it was all good.

The other thing that is likely, is the shop built the engine with very loose clearances. Pontiacs have very big main and rod bearings (compared to other makes), and if you set the clearances loose, the oil pump has trouble keeping up. There is no high volume pump for Pontiac, like there is for chevy. And if the shop set the engine up like a performance BBC, (greater than .001 per inch of journal) it's going to struggle to maintain pressure. A BBC has a 2.75" main journal, a Poncho 455 is 3.25".

*edit* Does the engine have valvetrain noise? The shop could have used chevy lifters, which have the oil band in the wrong place vs a Pontiac. That would bleed off oil pressure.

[1qwerty]

Engine sounds great and runs great
Just no oil pressure
No valvetrain noise at all

[moneypit]

Originally Posted by Lee

I use Jeff @ Westside Machine & Performance for my machine work.

I also sent you a message (upper right hand corner of the page).

x2 on Westside Machine!

[mgarblik]

I agree with Steve. If a gallery plug was missing, even with 20W-50 oil, I don't think the engine could maintain 10 PSI at idle. Probably would be zero and maybe 10-15 PSI @ 3000 RPM. Also, there would be valvetrain noise with a plug pushed out. However, just a small sliver of RTV or other debris in or around the check ball and spring in the oil pump would produce your symptoms. Is there evidence of way too much silicone sealer being used or pushed out of the front cover seal or oil pan? That might be a telltale sign.

[1qwerty]

The use of silicone looks to be minimal
I have used westside before on a old Jeep CJ8 build last year and was pleased with the work.
I am a Owens Racing orphan.