383 Oil Pressure Too High

[lux]

Originally Posted by Richard2112

When I built my 383 I measured absolutely everything and I do mean everything. If it wasnt in my spec range I had it machined into my spec range. Had I written it down as I proceeded I'd have blueprinted by build. My rotating assembly was also balanced. But at each step of the build I was looking for tolerances that gave me assurance that I could run 10w30 oil. I don't recall now what those specs were (I measure for a great many other reasons also) but I do know that my clearances allow for 10w30. If your clearances are greater than the .001 per inch of journal diameter then a heavier oil may be warranted depending upon how much beyond that tolerance the clearances are. I use a standard pressure pump on my build and it does fine.

Good info, Thanks Richard.
I bought a blue printing book and measured everything many, many times. I also wrote every measurement down. It was my first build and a lot of money in parts so I did not want to screw it up.
I think everyone is right and I need to swap to 10w30. Lots of smart guys on here even if some think asking for advise is " A silly complaint"
Actually I'm not sure why the Skip White paper work suggests 20w50 in the first place. But, I'm learning my lesson on their advise or lack of it.
Thanks

[Richard2112]

Originally Posted by lux

Good info, Thanks Richard.
I bought a blue printing book and measured everything many, many times. I also wrote every measurement down. It was my first build and a lot of money in parts so I did not want to screw it up.
I think everyone is right and I need to swap to 10w30. Lots of smart guys on here even if some think asking for advise is " A silly complaint"
Actually I'm not sure why the Skip White paper work suggests 20w50 in the first place. But, I'm learning my lesson on their advise or lack of it.
Thanks

You may yet find that your oil pump gives you high readings. But if you know your clearances are within range to run 10w30, I'd recommend running it. 20/50 used to be the old school solution to having good oil pressure with bearing that had seen better days. Not sure why anyone would recommend 20/50 in a newly rebuilt stroker.

[truckdude239]

Never heard of one dieing from high pressure always hear of them dieing from no pressure my bosses 88 s10 blazer runs 80psi at cold start 60 warmed up and back to 80 when on the gas and its never had an issuse id swap to 10w30 with that said the only gasket I could see leaking under pressure is the disbirtor one. Most of the other gaskets are not under pressure just keep oil that spasheds around

[lux]

Originally Posted by truckdude239

Never heard of one dieing from high pressure always hear of them dieing from no pressure my bosses 88 s10 blazer runs 80psi at cold start 60 warmed up and back to 80 when on the gas and its never had an issuse id swap to 10w30 with that said the only gasket I could see leaking under pressure is the disbirtor one. Most of the other gaskets are not under pressure just keep oil that spasheds around

A small oil leak from the distributer gasket is a strong possibility. I'll look closer, I think it's coming from that area. But, like I said it's small and thats why I'm having trouble finding it. The valve cover leaks are solved, I bought the right gaskets.

Thanks

[geezer#99]

Use baby powder to check for leak sources.
Use a small syringe to apply it.

[hjewell2]

Originally Posted by richard2112

oil viscosity for your engine is determined by the tolerances at your main and rod bearings and also upon the smoothness of the finish of each. A polished finish can work well with tighter tolerances and a thinner oil will develop a good hydrodynamic wedge for the journals to ride on. As your tolerances get looser and the finish a bit more rough a heavier weight oil is necessary. A general rule of thumb for engine building is to allow .001 clearance for each inch diameter of journal.

bingo!!!!

[lux]

My clearances

[lux]

Also the crank is polished

[sweetk30]

my new gm long block L31 is running 5-30 oil mobil 1 . she pegged the stock 60 guage from day one . so i swapped in a diesel guage and sender for the 80 psi and she is good to go now .

[lux]

Originally Posted by lux

My new built 383 oil pressure is high.
Idle pressure is 65psi @ 1000 rpm after warm up
5000 rpm is 95 psi.
Milage on the engine is 1100
The oil I’m running is VR1 20w 50
7 Quart oil pan, but I’m using 6.5 Quarts
oil filter is Fram HP4

I think the problem is the pump
I put in a Melodon 18756 , Standard Volume , High Pressure pump. I thought it was a standard pressure pump.

Do I have a problem?
Do I need to change to a standard pressure oil pump spring?
I seem to have a lot of small oil leaks.

I changed to VR1 10w30 and a 10 micron K&N oil filter. The old filter was 5 microns.
The numbers now are;
Idle pressure is 40psi @ 1000 rpm after warm up
5000 rpm is 80 psi.
So, the oil change decreased the pressure by 15 psi.

That still seems a bit high and I'm considering changing to the lower pressure spring in my oil pump. Any sugestions?

[geezer#99]

If you’re dropping the pan it’s likely better to change the pump.

[lux]

Originally Posted by geezer#99

If you’re dropping the pan it’s likely better to change the pump.

I called the folks at Melodon and they said the high pressure and standard pressure pumps are the same. The only difference is the spring. Am I missing something here?

[gmc684x4]

the spring controls the pressure the pump puts out one spring will relieve more oil then the higher pressure spring will operate at a set higher pressure

40 Psi at idle is good 80 at 5 K is ok as well how often do you keep it pinned at 5 grand ?
most road trips will be around 1600 to 3500 is rpm with the odd spirited ramp to 5000 rpm

I will guess and say it was the diesel truck oil and the low micron filter pushed up your pressure too high

It is an old school trick to either drive a motor with a bad bearing longer or sell it for more as the oil pressure seems more normal to use 20W50 in a sbc
it is thicker providing a better wedge from the worn out bearings and the crank

[geezer#99]

Originally Posted by lux

I called the folks at Melodon and they said the high pressure and standard pressure pumps are the same. The only difference is the spring. Am I missing something here?

Changing the pump could save you pulling it apart again. You’re assuming it’s the spring and not a pump defect.
But then on second thought just swapping the spring saves you needing to redo pan clearance for the oil pick up and brazing the tube to the body.

[lux]

Originally Posted by gmc684x4

the spring controls the pressure the pump puts out one spring will relieve more oil then the higher pressure spring will operate at a set higher pressure

40 Psi at idle is good 80 at 5 K is ok as well how often do you keep it pinned at 5 grand ?
most road trips will be around 1600 to 3500 is rpm with the odd spirited ramp to 5000 rpm

I will guess and say it was the diesel truck oil and the low micron filter pushed up your pressure too high

It is an old school trick to either drive a motor with a bad bearing longer or sell it for more as the oil pressure seems more normal to use 20W50 in a sbc
it is thicker providing a better wedge from the worn out bearings and the crank

Good info, thanks.

In my conversation with the guy at Melodon he explained a lot about the pump, pressure and how to change the spring. Hats off to good customer service. Their pumps cost more but I'll pay for good service any day.
Of corse I'll have to raise the engine to change the spring but thats the only hard part.Changing the actual spring is simple. I think I'll wait a while before I make that decision.

[MySons68C20]

Oops, wrong thread!

[garyd1961]

Been driving mine for 5 years with the gauge pegged at start up and past 3/4 driving down the road with the engine at operating temperature. I think you may be fixing a non-problem.

[lux]

I finally got the oil pump spring changed. I went from a pink(70psi) spring to a green(49psi) spring. What a pain in the @#@! to change such a small part. I should have just pulled the motor because of my after market oil pan with windage tray. But, I got it done.
The new pressure when warm is;
Idle 900rpm = 40psi
4000 rpm = 65psi
This is also after switching to 10w30

I also fixed the oil leaks again and they seem to be gone for good this time.

[cadillac_al]

Problem solved. I was going to say since your clearances are perfect you must have a high pressure oil pump. Oil pressure doesn't need to be that high. Mine has a high pressure pump too and I am scared of blowing an oil filter on cold winter days.

['68OrangeSunshine]

Originally Posted by lux

Yes, The 20w50 is a recomendation from the engine designer,
Also I was under the impression that a Fram HP4 was a good filter for a high proformance engine,, please give me any better suggestion.

I wouold take advice from ''Yankees'' about oil viscosity with a grain of salt. They have no concept of the Summer surface temperatures we deal with in the Southwest. VR1 20W-50 is what I'd use, especially if the designer said to.
Frams aren't made the way they used to be. I prefer Wix 51060 oil filter.