[Navy Horn 16]

Hey guys.

Got a 77 Pontiac TA. 400 block, all aluminum top end. E-Heads via KRE, Headers, hybrid cam setup, a little over 400hp. Got an 800 CFM Q-Jet on it.

Typically, idle oil pressure sits around 20psi, and as soon I get up to anything above 1000K, it sits above 40, around 60 under hard acceleration.

Today, When I got into it, I looked down and had zero oil pressure. Furk. Let off, and it popped right back up to 60. Hit the accelerator a few times and as soon as it really starts to pull, pressure drops. I didn't let it get low at all. Check the oil, and I'm about a quart below my 6Q line. Add a quarter, oil level is back to full, and test the car again.

This time, it stays high until about 70MPH (that didn't take long) and then drops to 20 and stays there until about 120pmh. The second I let off the throttle, it pops back to 60PSI. Tried a few more pulls, and it seems that the oil pressure gauge is linked to my secondaries in the Q-Jet. As soon as the secondaries open, oil pressure drops 20 pounds. WTF?

My last oil change was at Sears, so I didn't hand select the oil filter. I'm running 10W-40 with a can of Lucas. Could this be a filter problem? I've heard of some filters having some kind of relief valve that bypasses under pressure. Could the filter think that it is clogged due to the high pressure and simply bypassing?

It's hot as F right now, and I'm not reaching back behind those headers to undo the filter.

Any ideas, please let me know.

[Formulas]

check your wire on your sending unit for tightness and condition.. engine torques over you lose some contact

[Navy Horn 16]

Sorry, should have added that it is a manual gauge, not electric. No leaks.

["QUICK-SILVER"]

Kinda sounds like the pickup may have fallen off the oil pump. Pump still works but oil level drops below the pump inlett hole when you rev the engine. At low rpm oil drains back fast enough to keep the pump submerged.

When oil pump pressure relief is acting up, pressure don't come back when you let off the gas. Works pretty much opposite to what you're describing.

Filter and filter bypass let oil pressure go on to the engine if there's too much restriction in the filter. So that don't sound like your problem.

I think I'ld drain the oil and and fish around with a piece of wire, through the drain hole, to see if the pickup tube fell off.

Beyond that, IDK

Good luck

[lust4speed]

I'd also go with a detached oil pickup. Was it pinned or spot welded in place?

[steve25]

X2 with quick silver, time to go fishing!

[lfdsteve]

I had a similar problem. After switching to a canton road race pan. Seems I didn't allow for the increase in oil capacity so after running for a while, enough oil would collect in the top of the engine so my pickup would uncover during acceleration and cornering. Oil pressures normal during cold start up and brief normal driving.
Just a thought

Steve

[wheneaglesfly]

I agree.
There is a problem with the Oil pickup tube.
Likely loose and resting against the pan floor.
Needs 1/4-3/8" clearance.

The Stock Pontiac oil filter adapter has a Huge Bypass built into.it.
3X The size of SBC & BBC.
Engineered to delivered Full Flow regardless of Filter used like a Crap one.

Its Hot as Fick here too in Illinois .

[salem1912]

I would try a different filter first. There may be a flow (volume) issue with what on it from sears. at work I see a lot of newer Hemi engines come in for a oil change and have a small 4 cylinder filter screwed on from one of the chain stores.

[gtofreek]

Older E-heads were famous for puddling oil up inside the valve cover.

[dataway]

Gives you an excuse to go out and get one those Milwaukee inspection cameras ... drain the oil and stick that up in the pan look around.