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Old 06-04-2013, 11:56 PM
MJVAUGHANS MJVAUGHANS is offline
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Default 287 oil pressure

1. What should the oil pressure be, at idle, of a 287 v8?
2. Is it possible to increase this pressure with a modification to the pump, spring? Would this have other effects?

Mine will drop to 5-10 or so when idling, but is about 35-45 when the engine revs/running down the road.

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Old 06-05-2013, 07:38 AM
Pontirag Pontirag is offline
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The rule as taught to us in auto shop, the army and as aircraft mechanics is 10 psi per inch of crank diameter.

5-10 at idle is a bit low

but the 35-45 isnt bad

no problem shimming up the spring a bit but dont go all crazy.

if the engine is a bit tired then extra oil pressure will throw more oil up on the cylinder walls and the rings may not get it all off, that may cause oil burning symptoms,

also may push a bit more oil past the rear main seal, more of a problem if you run a manual tranny, not so much a problem with hydro's

Using thicker oil will cause you more problems with the rings. even when warmed up.

I would put one or two washers behind the spring and use 20 wt and see what happens, maybe go with 30 wt in summer.

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Old 06-05-2013, 08:18 AM
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Increasing the spring pressure will make no difference at idle.

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Old 06-05-2013, 03:13 PM
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then increse the idle speed to the high side of the acceptable range

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Old 06-05-2013, 09:45 PM
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My 62 Pontiac service manual says to test run the warmed engine up to 2600 RPM and oil pressure should be 30-40 psi. There is no idle psi specification, however the low oil pressure switch is supposed to come on at 5 psi or + or - 1 1/2 psi from 5 psi. The service manual also says "Caution: do NOT attempt to change oil pressure by varying the length of the pressure regulator valve spring".
My 69 Pontiac service manual says standard oil pressure should be on a warmed up engine and 30-40 psi at 2600 rpm and 45-50 psi on GTO & 428 at 2600 rpm. It also says H-O engines should be no more than 60psi over 2600 rpm. It also says do NOT attempt to raise or lower oil pressure by varying the length of the pressure regulator spring.

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Old 06-06-2013, 01:55 AM
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probably not a good idea to alter it however its unlikely you will want to alter in to reduce pressure and increasing oil pressure will spray more oil up on the cylinder walls and will put an increased load on the distributor gear to cam shaft drive.....if the oil pump is producing factory spec oil pressure. how ever...

wear and tear will alter it over time typically reducing pressure

and increasing oil pressure by shimming up the spring to return pressure to its normal range does alter its pressure.

but on a technicallity, I dont condone altering the length of the spring, I'm suggesting adding a washer or two to increase pressure of the existing spring. maybe a nit picky detail but read on and see for your self if and what matters

back in the day people would pull springs out and stretch them to increase oil pressure but its an even more temporary fix than shimming up a used spring. and actually worse if the engine is a high milage engine. racers used to groove thier mains to get better lube circulation but saw thier oil pressure drop to scarry levels so as a cheap fix (and on POS used cars!?!? ) the would pull out the oil pump spring and stretch it about 25% and magically thier oil pressure is back in the safe range,

another option would be to buy a brand new currently manufactured pump and strip it of all its guts and install them on the old pump.

you could always search to your hearts content for a nos pump for the 55-58 v8's but good luck there, I have not seen one new for those years for several years and although some are advertised for sale for like 2-300 dollars, they are always out of stock.

rebuild kits for these pumps are also marketed but are essentially a kit of guts from a modern pump repackaged as such.

and be carefull of ebay vendors who do market "NOS or NORS" oil pumps, there are a few unscrupulous vendors that sell 59 and later pumps with a NORS box or packaging from a 55-58 pump in the picture but reading the item description the seller is uncertain or evasive about what it fits, one vendor in particular sells one that fits " 57 to 62 year engines" but the packaging shows a NORS PN# for a 55-58 pump, but in reality the pump itself is a 59 and later pump. further enquiries from this vendor result in even more "confused and uncertain" responses about its provenance. This person knows better and has been called out on it ( he owned several auto parts stores since the 60's so should...and does know better, buy hey! thats the market) what he does is shows a picture of a 59 and later pump with a slightly damaged 55-58 box in the background, when you recieve the pump itself, there is no packaging, but mysteriously the same identical slightly tattered box reappears in the next pump picture where he is advertising yet another "55-62 pump" for sale. he knows exactly what he's doing because he has owned several auto parts stores over an almost 50 year period of time and has a library of parts books that go back to the early 20's. ebay knows about him but since he pays his pound of flesh, our hobby suffers. oh and all sales are final. plus his payment arrangement does not allow you to get compensation from pay pal. soooo caveat emptor.

if you dont feel confortable increasing oil pump pressure then you can always install new rod bearings. that is as cheap and rod bearings are the same for all years.

that will probably bring desired oil pressure back into the low end of safe range for a while but does not solve mains wear.

replacing mains is another possibility but the bearings are getting hard to find in std and .001, .002, and .003 over size mains for the 55-56 engines

Bill is correct that shimming up the spring will not change oil pressure at idle however it takes very very small increase in RPM for the oil pump to pump up pressureto max rated pressure at which time exess oil is by passed. see for your self simply by reving up your engine and watch how just a little increase in rpm's will raise psi quite a bit almost instantly. I think the rule is that doubleing pump rpm's increases psi 4 times.

As a rule I always install a new 60 psi pump in any used engine I intend to run, even at rpm's as low as 325 idle I notice an improvement in pressure and not just guage pressure but the lifters quiet back down too. But since oil pumps for the older engines are not available this wont work for your 55.

something to consider if you buy an NORS pump rebuld kit or use the guts from a newer kit or pump in your older pump:

some new pump pressure relief balls are of a different diameter than the 55-58 factory balls and balls from different 55-58 NORS pumps and even NORS pump rebuild kits are different diameter than factory balls. If you can re use your factory ball go for it but if your ball is bad in any way or wrong diameter no big deal, hardened steel balls are available in many many diameters from several vendors including Ace hardware stores and McMaster Carr. they are sold as individual replacements for use in ball bearings. so are of hardend high quality steel.

also when you pull your old pump guts apart look at the old spring. if it has been working correctly, you will see flat spots on the outer surface of the spring where it rubs against the inner surface of its housing. Thats a good sign that the pump spring has done its job correctly but is badly worn and will show up as reduced oil pressure, squeezing the spring together between your index finger and thumb will show you how much weaker it is than normal but even closer observation will show that when the spring is squeezed and collapses it appears to kink a little bit where it has thinned outthe most due to wear. so shimming a pump with this kind of spring wear is false economy, better to put a 60 psi spring and a new or good ball back in its place.

So as Bill said: installing a new hi psi spring or shimming up an old spring technically will not make a difference at a set idle rpm but it will almost instantly and significantly increase pressure at any rpm's above that idle speed. and apart from rebuilding your engine is the most cost effective way to restore oil pressure. but it wont fix worn parts.

for that you must get those little pills from JC Whitney and drop them into your engine

on a 55 287 a 56 316 and two separate 347's after searching for a new oil pump(they dont come with the floating pick up either) I simply installed the guts from a current melling 60 psi pump and even at idle the increased oil pressure was impressive. I used streight 30 wt in all my engines winter and summer.

Pulling your pan to do this, you might just pull the old pump off completely and soak it in carb cleaner, and pull it apart to look at the gears too. usually the pick up screens are getting close to being clogged up, and sludge may be constricting the picup tube or keeping it from pivoting as it floats, the internal pump gears are helix shaped and are of high strength steel rather than sintered or powdered metal like later ones but they are prone to rust and pit if there is water in the oil, from condensation or cooling system leaks. If your gears are worn or pitted, dont worry either because the gear sets from a newer pump, while streight cut and powdered metal are plenty strong and entirely servicable as a replacement. it is also an excellent time to replace your timing chain and gears too.


Last edited by Pontirag; 06-06-2013 at 02:24 AM.
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Old 06-06-2013, 05:15 AM
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I stand corrected in regards to a statement I made above:

double the rpm's of these types of pumps do not increase its pressure or volume by a factor of 4.

Mia culpa

l


Last edited by Pontirag; 06-06-2013 at 05:22 AM.
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Old 06-06-2013, 07:49 AM
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Are you using a good accurate gauge (and not the stock gauge) to test the pressure?

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Old 06-06-2013, 09:22 AM
MJVAUGHANS MJVAUGHANS is offline
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I am just using the stock gauge on the dash. After these informative postings I observed more intently while varying rpm and cold vs. warm engine temps, and it looks like my idle pressure is probably more like 15 lbs. at idle. Not 5-10lbs. The highway speed pressure is pretty consistently at 44-45 range, and normal around town about 30 or so. I know I have crazy oil flow to my rockers because I have put rocker arms on with pushrod holes now. I was just paranoid about lower end lubrication because I have been fighting a continuous battle with destroying pushrod ends(long story) and I did not want other issues to develop to complicate things right now.

I think I am going to keep an eye on it for now and just run it.

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Old 06-06-2013, 10:20 AM
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Nothing wrong with a Idle and 15psi when the engine is warm. Why don't you hook up a good mechanical gauge just to make sure.

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Old 06-06-2013, 11:13 AM
MJVAUGHANS MJVAUGHANS is offline
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Good idea.

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Old 06-06-2013, 09:07 PM
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there are two places to hook up a guage, the factory uses the fitting on the side of the filter mounting housing, the other place is right next to the distributor. You might hook that guage to either outlet and see if ther's a difference between sources.

sometimes the roof dont leak when there is no rain

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Old 04-23-2020, 01:31 PM
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UPDATE:

For anyone who cares about the outcome of this issue, I discovered after tearing the engine completely down to rebuild, again, that my oil pump had a chunk missing out of the seat where the pressure regulating steel ball sits down in the cast iron housing. Therefore I do not know how much or when the regulation was happening. Repair would be cost prohibitive, apparently 1 year only 1955 Pontiac/Gmc oil pump body is next to impossible to find. I did finally find ONE for sale and paid almost $300 to get it, but in the end I did find a replacement. Still had to do the complete rebuild because of the issues it caused though.

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Old 04-23-2020, 05:50 PM
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What's different about the '55 pump? Both 1960 Pontiac Master Parts Catalog and 1960 GMC Master Parts Book calls out part number 523473 for 287,317,347 and 370 Pontiac V8s and 288, 316, 347 and 336 (before engine number 33635001) GMC V8s. The earliest pumps had helical instead of straight cut gears, but the gearsets interchange.

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Old 04-23-2020, 06:32 PM
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Nice of you to follow up, what did you find and have you made any upgrades?

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Old 05-20-2020, 04:56 PM
MJVAUGHANS MJVAUGHANS is offline
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694.1,

As far as upgrades during the rebuildMemory may be sketchy)
1. Old stock rebuilt complete original configuration oil pump.
2. Machined valve guides and installed positive seals.
3. Machined down and threaded rocker studs and installed ARP screw-in studs.(So no more stud oiling)
4. Replacement stamped steel rocker arms with the hole for oiling through the push rods.
5. Comp Cams chrom-moly push rods in the correct length to account for the changes being made.
6. Stud oil galleries in the heads were thoroughly cleaned, then I threaded the front holes and installed a screw-in plug with a relief hole to allow the oil to continue to flow from the cam journals up through the heads when they were stud oiling, but not have that oil trapped in the heads with no way to get out.
7. Double stacked cork valve cover gaskets so the stock valve covers would not make contact with the new studs and rocker arms.
8. Changed the double valve springs, to single beehive style.
9. Used 1956 hydraulic lifter part#. (1955 was literally 1 year only)
10. Removed road-draft tube and installed a pcv valve venting back into the carb riser block.
11. Timing cover machined to accept rubber seal around crank snout to replace cork/spring setup.
12. Pertronix points conversion in distributor.
13. Oil bath air cleaner gutted to run a paper type filter.

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Old 05-20-2020, 05:08 PM
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Quote:
Originally Posted by MJVAUGHANS View Post
694.1,
6. Stud oil galleries in the heads were thoroughly cleaned, then I threaded the front holes and installed a screw-in plug with a relief hole to allow the oil to continue to flow from the cam journals up through the heads when they were stud oiling, but not have that oil trapped in the heads
Just curious: What is the path the oil takes from the plug's relief hole back into the engine?

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Old 05-21-2020, 10:34 AM
MJVAUGHANS MJVAUGHANS is offline
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Bill,

I wish I had pics with me to show, but here is the gist.

There is a hole in either end of the cylinder head that blocks off the ends of the oil galley that runs under, and feeds, the stud oiling. I removed the plug on the front end, used a tap to thread it to accept a pipe plug that I drilled a relief hole through the center. (notes: 1. The plug has to be ground down so when fully installed it does not hit the bottom of the first rocker stud in the galley, or I guess it could just hang out the front also. 2. I determined the size of the one relief hole per head by adding the diameter of each of the original stud oiling holes and drilled 1 hole that size. Just a logical guess and could be changed.)

To answer your question now. The oil squirts out the bypass hole and just returns to the crankcase by running out the hole at the end of the head per original design.

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Old 04-27-2020, 09:06 PM
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"on a 55 287 a 56 316 and two separate 347's after searching for a new oil pump(they dont come with the floating pick up either) I simply installed the guts from a current melling 60 psi pump and even at idle the increased oil pressure was impressive. I used streight 30 wt in all my engines winter and summer."

That's exactly what I did on my '57 engine. Made a dramatic change for the better.http://forums.maxperformanceinc.com/...attach/jpg.gif
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Old 05-18-2020, 02:35 PM
MJVAUGHANS MJVAUGHANS is offline
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The guts are swappable with later parts. Even considering the straight cut vs. helical gears I believe they both fit just fine. My problem was that the cast iron body was damaged on mine. The mounting holes and alignment is different on the 55-57. I bought the newer style pump and tried to make it work but it just would not line-up. This has been researched by others also on the Pontiac bulletin boards, but I had to see for myself because of the difficulty in finding the correct body.

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