Oil pressure in a 59 ab v8

P

Peatea

New member
I bought a 1932 coupe ,powered by a 59 ab ,(fully rebuilt), on startup and at idle oil pressure is70psi at 50 mph it is 90psi ,I was told it had a high capacity oil pump but my question is, is this oil pressure too high? It does not leak any oil and would fitting a remote oil filter reduce pressure ? Cheers Pete
 
90psi does seem high.

Fitting a bypass filter may reduce it very slightly but not significantly. I'm not sure if having 90psi oil pressure is a problem as such, except that you are wasting engine power by having to generate that amount of pressure in the oil pump.

Experts may have different opinions, but personally I'd take a bit of pressure out of the relief valve spring to bring the numbers down a bit. Someone may have shimmed the spring to bump the pressure in the motor when it was worn (pre rebuild).

If it were mine and it was reading 50psi when driving along I'd be more than happy.

Mart.
 
This can cause crankshaft and bearing failure. We discovered this back in the 60's when we thought more was better. Smokie says 10 lbs per 1000 revs is all you need and that;s in engines that put out more power than a flathead.
Stupid is, what stupid does.
 
It is possible that you have a high pressure, high flow (M-15) type oil pump in your engine that is normally used in a racing engine with more tolerance in bearing fit up.
 
The OEM oil pressure regulator valve may have been blocked off if a late type pump was installed. 70 to 75 is a good upper range for most engines but flat motors can run in the 25 PSI range and survive OK. Much more than 70/75 psi and it washes the cylinder walls too much. The floater bearings can take a lot lower pressure but the oil would be squirting around all over the place with the higher pressures.

A person may be able to reactivate the regulator valve in the front of the valve chamber and lower the pressure. Make sure you have a known accurate direct reading pressure gauge to do adjustments.
 
Ronnie has asked the right question.
Change the oil to something like 10-30 and see what pressure is like.
I use a stock "long" pump and use 5-30 oil. Oil pressure is 50 + at startup
and 35-40 on the road at operating temp of 175-180
 
Sound like the pressure relief valve is not working or not working correctly, as stated by rotorwrench. It would be much easier to replace and adjust the original in the valve chamber, again as suggest by rotorwrench. You can play with the spring pressure to adjust the pressure and, as stated be sure you have the correct oil viscosity and an accurate pressure gauge.
 
As other have said, oil pressure is not a thing where "more is better". I had an O/T Corvette engine rebuilt, and the builder installed a hi-pressure, hi-volume pump. It caused all kinds of problems : oil burning, copious smoke on start-up, a constantly pegged guage, and fouled plugs. In the end, the only way to fix it was to remove the "racing" pump and replace it with a standard pump with a standard spring.

A flathead, which is a simpler engine, probably would not have had all of these problems, but too much oil pressure can be a bad thing. Hopefully you can find a way to alleviate the problem without tearing down the engine and replacing the pump like I had to do.
 
I remember the old cartoon of Lead foot Louie who roared around in his roadster with 90lb oil pressure and the saying goes he blasted his bearings.
Any way are you sure your pressure reading is correct.
 
Here is a wild hair brained idea. Use the by-pass filter system and adjust the restrictor size to drop the engine oil pressure down 20 to 25 psi (90 - 20 = 70). No idea if this would work, but seems like it should as long as the return line was large enough diameter to allow flow back into the pan without building up pressure in the canister.

Or just a small diameter line straight from the rear port to the pan fitting and bleed off the pressure that way by adjusting the line size?
 
If too much oil pressure is bad for a motor, my old 21 stud should last forever!

Mart.
 
Mart said:
If too much oil pressure is bad for a motor, my old 21 stud should last forever!

Mart.
Click to expand...

Now that is funny!:)

We were always told back in the old days that when the oil pressure got up above 60 it started to blast the surface off of the bearings. I would assume that this would be a slow process and not be of any importance in a racing application. But in a street car it would shorten the life of the bearings. No idea if this was theory or based on actual testing or urban legend, but that was the story told.
 
I have a 59AB, stock 8BA short pump, newish engine. Hot idle is about 35-38 lb., hot running- 63lb. I use both pressure reliefs, the 59ab one at the front of the block and the one in the oil pump...

I like the idea of using a mechanical gauge.

Karl
 
I agree with those above. In excess of 70 lbs seems needless and possibly troublesome (?) I would be concerned long-term about your oil seals. If you change oil about every 1000 I think its better to adjust relief valve than to install a filter system. Have a 59AB w/34,000 on rebuild; whoever rebuilt it did good; I use reg 10W-30 no filter; stock pump; 80lb elec sensor, gauge plus a mech gauge - both indicate about same data; 70lbs cold at idle; abt 20lbs hot at idle; 55/60lbs hot at 60mph. Let us know how you resolved the matter.
 
Hi guys ,cheers for all the advice ,sorry I've taken so long to reply but been a bit busy , yes it has got a mechanical pressure gauge and the first thing I'm going to do is try some lighter oil ,cheers guys I will keep you posted regards Peatea
 
Question to the experts ... below stated "installed a hi-pressure, hi-volume pump" ..... so if you install an M15 style pump ... is higher volume (I believe 25% increase in volume is the stated mfg claim) synonymous with higher pressure??

As others have stated - lots of other variables like bearing tolerance set up, oil viscosity, RPM range expected to operate, etc. Correct?? :confused:

tubman said:
As other have said, oil pressure is not a thing where "more is better". I had an O/T Corvette engine rebuilt, and the builder installed a hi-pressure, hi-volume pump. It caused all kinds of problems : oil burning, copious smoke on start-up, a constantly pegged guage, and fouled plugs. In the end, the only way to fix it was to remove the "racing" pump and replace it with a standard pump with a standard spring.

A flathead, which is a simpler engine, probably would not have had all of these problems, but too much oil pressure can be a bad thing. Hopefully you can find a way to alleviate the problem without tearing down the engine and replacing the pump like I had to do.
Click to expand...
 
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