# Oil Pressure and Distributor



## knucklehead12 (Nov 14, 2013)

The engine on my 68 GTO is tired. It usually would show decent oil pressure when the car was first started and the oil was cold and thick. But after it warmed up, the pressure would drop to about 5 psi at idle and go to about 20 psi during acceleration. I recently purchased a remanufactured distributor and installed it. When I started the car, it showed 50+ psi and maintained 30+ during the 30 minute trip. I do not think the original distributor had ever been out of the car. I know the engine is tired and i am waiting to get some cash to build it. The car is running great now, but I am baffled as to why it has more oil pressure with a new distributor. Has anyone else seen anything like this?


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## Roger that (Feb 6, 2010)

At the very end of the distributor shaft is a hex like key (1st pic). This will slide into the hex shaft on your oil pump. If the hex key on your old distributor shaft is worn out and/or the shaft of the oil pump is wore there will be slippage.

If you still have your distributor look at the very end of the shaft below the distributor gear. In my 1st pic that is a Ford distributor shaft without the gear. In the 2nd picture I took an allen wrench (for the Pontiac I think it is a 5/16" size) and slid it up the distributor shaft and twist the two to see if there was any slippage.


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## knucklehead12 (Nov 14, 2013)

That would make sense if it were a hex fitting, but mine is a slot like a flathead screwdriver. Really cannot slip.


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## geeteeohguy (Feb 2, 2008)

Never seen a hex distributor on Pontiac....that's strictly Ford. Pontiac is slotted, as stated. And ONLY slotted. Knuckle, where is your oil pressure line connected....at the oil filter housing or at the distributor?


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## Goat Roper (Oct 28, 2014)

Is it possible that the check valve in the pump was stuck open then closed when the new dist. was installed?
Just spitballin' here but I can't figure out how changing it would affect the oil pressure.


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## knucklehead12 (Nov 14, 2013)

The sending unit is on the oil filter housing. Several months ago I T'ed off the sending unit and added a real gage. That is what I am basing the low readings off of. I can't figure it out either. Makes no sense.


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## geeteeohguy (Feb 2, 2008)

Yes, it's where it 'should' be. I was thinking that if it were connected up near the distributor port, that possibly a chunk of debris got removed, etc. It doesn't make sense to me, either. If it has good oil pressure and runs good now, though, run it!!


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## BearGFR (Aug 25, 2008)

Mystery to me too.... Do you still have the old distributor? I've got one really wild and scary hairbrained idea. If you do have the old distributor still, check inside the drive gear and on the end of the shaft for signs of excessive wear, friction, broken tang on the distributor shaft, etc. I know this sounds nuts - it does to me too - but what if either the previous "installer" either didn't get the distributor seated onto the oil pump drive and the only thing driving the pump (until you replaced the distributor) had been plain old friction? Something like that...

Otherwise, I'm baffled.

Bear


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## geeteeohguy (Feb 2, 2008)

Bear's idea makes the most sense, but for that to happen, the old distributor could not have been installed all the way in the hole. There would have been a quarter inch gap or so. Still, it's _possible._


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## knucklehead12 (Nov 14, 2013)

Sorry meant to reply, but there was a lot of oil around the distributor suggesting that the distributor was not fully seated, but when I looked at the old shaft, it had wear marks on the 2 opposing corners suggesting that it was making the correct contact.


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## geeteeohguy (Feb 2, 2008)

There _is_ a gasket that goes between the dizzy and the block....I make my own out of thin cardboard.........


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## BearGFR (Aug 25, 2008)

What did the wear pattern on the distributor gear look like? 

Bear


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