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Oil pressure
https://slantsix.org/forum/viewtopic.php?t=23802		 Page 1 of 2
Author:  Bren67Cuda904 [ Thu Jun 28, 2007 11:18 am ]
Post subject:  Oil pressure
My oil pressure is pretty good when I am not hot. I think I am still going to install a washer behind the oil spring to bring it up a pinch. Right now I am using Rotella T 15-40
Cold idle 40psi
Cold 3000rpm 50psi

Warm = 20-30min driving.
Warm idle 25psi
Warm 3000rpm 43psi

Hot = 45-60 min lots of highway turning 3200 rpm for at least half the time.
Hot idle 7psi
Hot 3000rpm 35psi

Adding the washer may help this, but my question is after another few hundred miles for breakin, I was thinking about adding Amsoil's 10w-30 deseil Series 3000 (I already have a case) . Do you think the synthetic is more temperture stable and won't thin so much? Collant temp has never climbed over 190.
Author:  slantzilla [ Thu Jun 28, 2007 12:23 pm ]
Post subject: 
You can try shimming and different oil, but I have never had one of my motors go that low at idle. What RPM is that, and is that idling in gear?
Author:  Bren67Cuda904 [ Thu Jun 28, 2007 1:22 pm ]
Post subject: 
In gear with A/C running I am at 700 RPM. If I flip off A/C rpm rises to 950 and oil psi to 10.
I can drive all over the place and the pressure only goes this low if I really whip the oil for long periods.
Author:  Dart270 [ Thu Jun 28, 2007 1:25 pm ]
Post subject: 
I don't think a shim will raise the idle pressure. Then again, you don't need too much. You will want to shim to raise the higher RPM pressure, though. I shoot for 55-60 psi at 3000+ rpm.

Sounds like maybe they set your bearing clearances really loose, or your oil pump is not clearanced properly. I have my bearings in the 64 at 0.002" on rods and mains, and it runs 20-30psi at 1000rpm idle when it's hot and been beat on the road course.

Lou
Author:  emsvitil [ Thu Jun 28, 2007 1:57 pm ]
Post subject: 
Quote:
I don't think a shim will raise the idle pressure. Then again, you don't need too much. You will want to shim to raise the higher RPM pressure, though. I shoot for 55-60 psi at 3000+ rpm.

Agreed......

The oil pressure spring is a relief valve. It only affects the highest pressure possible
Author:  SlantSixDan [ Thu Jun 28, 2007 2:47 pm ]
Post subject: 
Spamsoil/Scamsoil: It's easier and faster just to flush $50 bills down the toilet.
Author:  AndyZ [ Thu Jun 28, 2007 3:48 pm ]
Post subject: 
Have you had your valve cover off when the engine was "hot" recently? Was there an ample or excessive amount of oil getting to the top of the motor?
Check with your engine builder and see what he clearanced your rod and mains bearings at. You may need some 50 weight for this paticular build.

AZ
Author:  Bren67Cuda904 [ Thu Jun 28, 2007 4:29 pm ]
Post subject: 
From this picture you can see the clearance noted on the front main bearing. As I remember the front was the highest value of the mains. I don't remember the rod clearances.
http://tinyurl.com/ynlual
.0030
Author:  Sam Powell [ Thu Jun 28, 2007 9:38 pm ]
Post subject: 
That is plenty of oil pressure.Fifty lbs at 3000 RPM is a nice goal, and makes you feel comfortable, but if there is pressure, there is oil everywhere. The rule of thumb is 10lb per 1k of rpm. Too much oil pressure on a slant will do more harm then good. I cannot remember how, but it blows out the gears for the distributor, or some such thing. I remember reading this over and over in the old Slant six news, of guys damaging their slant running too much oil pressure. I would not mess with it unless it drops down lower than that. And forget the fancy oils. Do the research here for the additive that Dan was recommending for older engines. That is where to put your money, and what your particular engine needs.
Sam
Author:  dakight [ Fri Jun 29, 2007 5:24 am ]
Post subject: 
Apparently too much oil pressure loads the oil pump gear and can cause premature wear and failure of both the pump and the cam. 7psi is the factory spec at hot idle, FWIW.
Author:  Doc [ Fri Jun 29, 2007 8:21 am ]
Post subject: 
Bren's engine is running a reworked / rebuilt factory pump. (die-cast alm., 5/8 impreler size)
If the low hot idle pressure is a concern, swapping to a thicker impeller aftermarket pump is a good option.

Which ever pump you use, the high RPM pressure should be set to not exceed 50-55 psi. (relief valve setting)
DD
Author:  Davey [ Sun Jul 01, 2007 6:55 pm ]
Post subject: 
Ten psi per thousand RPM is good...even for racing applications. Or so I've read. It will certainly be enough for street use. Davey
Author:  thomasj6604 [ Sun Jul 01, 2007 7:17 pm ]
Post subject:  What additive is it that Dan is recommending?
Quote:
That is plenty of oil pressure.Fifty lbs at 3000 RPM is a nice goal, and makes you feel comfortable, but if there is pressure, there is oil everywhere. The rule of thumb is 10lb per 1k of rpm. Too much oil pressure on a slant will do more harm then good. I cannot remember how, but it blows out the gears for the distributor, or some such thing. I remember reading this over and over in the old Slant six news, of guys damaging their slant running too much oil pressure. I would not mess with it unless it drops down lower than that. And forget the fancy oils. Do the research here for the additive that Dan was recommending for older engines. That is where to put your money, and what your particular engine needs.
Sam
Author:  Davey [ Mon Jul 02, 2007 4:10 am ]
Post subject: 
GM Engine Oil Supplement (EOS) that contains ZDT, I believe. He had a good post not too long ago about how much to add and how often. Davey
Author:  lindross [ Tue Jul 03, 2007 6:12 am ]
Post subject: 
We run Valvoline conventional 10/30. While hot at cruising speed we see 50lbs of pressure and at idle we see about 25lbs of pressure. That has been what we considered normal for as long as we've had our little slant running. From reading it's good to see that that is pretty normal. :D
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