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fat rat
07-15-2001, 06:57 AM
What is max/min oil pressure for a BB Chevy and how accurate is a eletric Gafrig gauge?

Chestah Cheetah
07-16-2001, 09:58 AM
I don't know the answer to that, but I would also like to ask the same oil pressure ? for a 455 olds. Fat Rat, I added a manual gauge to the block itself for a more accurate read out, ($20).

fat rat
07-16-2001, 12:00 PM
Hey Cheetah, was there a difference in the reading?

Chestah Cheetah
07-16-2001, 01:50 PM
None! Both read 20lbs. Everyone is telling me something different. The last guy that worked on it was the most helpful. No more leaks, smoke, or noises- but the pressure is still at 20. When it's cold it starts out at 45 then gradually down to 20 and stays there. I just talked to him and he says I should switch from 10-30 to straight 50 weight oil- high quality Kendall. Then I talked to the guy who did the heads and valve job and he said to stick with 10-30 and that the motor is not big enough for 50. I don't know shit about motors and who to listen to.

rivercrazy
07-16-2001, 02:07 PM
I'd use a strait grade oil. Stay away from conventional multi-grades in a marine application. A strait weight oil like 40W will not thin as much when it gets hot. As a result, your oil pressure will stay higher.
I use a 20W-50 multi-grade. However, its synthetic. I've noticed higher (when hot) oil pressures with it versus strait 40W conventional oil.
Your 20lbs oil pressure sounds low to me. I don't know much about Olds engines other than they have lubercation issues.
My 454 mag starts out at about 70lbs cold and then runs about 40-45lbs hot (even after running hard for a few hours)

Chestah Cheetah
07-16-2001, 02:23 PM
From my limited knowledge I know that most Olds that have lubrication problems stem from using a 6qt automotive pan. I have a 14 quart. 20 lbs is low so you can see why I'm nervous. What do you think of the 50W?

rivercrazy
07-16-2001, 02:43 PM
I'm not an expert in this area. It seems like if you run in a really hot environment (like Havasu), it might be OK. I'd try a less thick strait weight before trying 50W.
Call Mondello Performance and ask them for advise on your pressure question. They are the Old's guru's..

phillyray
07-16-2001, 02:48 PM
Fat Rat I been using Kendall G-T 50/wt. Oil psi hot at idle about 40-45,when running about 50-55,the mech. guage seems a little more solid than the electric.Mounted mech. guage in the back of the boat,just to compare.Dose this mean your boat has arrived?

fat rat
07-16-2001, 03:16 PM
Yo PhillyRay, got the boat last week and ran it last weekend, the boat looks and runs increditable. I do have some minor problems....I hope. Are you running a blower? I'm getting what appears to be condisation in the breathers......some say its expected.....but what is excessive?

Chestah Cheetah
07-16-2001, 04:00 PM
Rivercrazy, do you have a number for Mondello? I too am getting "steam" out of the breathers.

froggystyle
07-16-2001, 04:40 PM
By the way, it would be really tough to beat the Gaffrig gauge. Top of the line. I have no problems getting a good reading. The gauge is really stable, and accurate as bounced off of my mech I used to have hooked up, but removed due to no need.
I run 45-55lbs running at cruise (3500-4500) and around 40 at idle. 454, 10 qt pan, Melling High Volume pump.

boatnam2
07-16-2001, 04:49 PM
hey guys,i use vavoline racing 60 wt.and my pressure runs 80 pounds at all times cold hot etc etc.i dont know much about olds but 20 pounds dosen;t sound right.

DetroitJim
07-17-2001, 04:52 AM
My experience with many engines of all types is that oil pressure is almost entirely a function of main and rod bearing clearance. Maximum available pressure is determined by the oil pump pressure relief spring. If clearances are too large, oil pressure will be low and vary widely with temperature and rpm. 20 lbs at idle and 40 lbs at speed is what I would expect on an Olds with a stock pump and some bearing wear. On my big and small Chevys I use a stock pump for all applications, even supercharged. If the crank is ground at the high limit dia., I get 55 psi cold idle and 30-50 hot. If I grind the crank 0.0005 smaller, I get 50 cold and 20-45 hot. High volume pumps and high pressure springs will overcome loose bearings, but will hose down the cylinder walls with oil and overwhelm the rings.
Jim

rivercrazy
07-17-2001, 07:34 AM
Sounds like Detroit Jim has some good answers here. Mondello Performance Group's # is (805) 237-8808.

MrHavasuCat
07-17-2001, 08:20 AM
Run a high capacity oil pan, and an oil cooler would probably help as well. I run both on a blown 510 and my pressure ranges between 50-80 pounds. I run penzoil 20/50 and change every 25 hours.

Brewer
07-17-2001, 09:57 AM
Help. Fresh BBC 454 w/ stock oil pump, factory rod/main bearing clearance, Olsen oil cooler, straight 30 wt. Oil pressure cold (idling) was 60-65 psi, after warm-up comes down to 40-45 (idling), back up to 60-65 @ WOT. 2nd day out still had decebt pressure idling, but as RPM's come up, oil pressure was going down to 30!!!??? WTF! Needless to say I didn't keep it @ WOT, with only 30 psi. Anybody have similar experiences or insight?

sgdiv7
07-17-2001, 10:43 AM
I think I know your problem, the clue you gave is fresh motor. I think the oil pump pick up fell out or swung.
Bill

Chestah Cheetah
07-17-2001, 11:11 AM
Here we go! I called Mondello (thanks Rivercrazy) and they said when cold it should be 100, 70-75 hot. That high? I called my guy back and he said thats way too high. We don't know what size the oil pump is but I would only assume since it has a large pan (14qt) it would have a high volume pump also. He says 20 is low, but I'm safe driving it like that as long as I don't mash it past 5500. I asked about the 40W and he said you could but he would go with 50W Kendall. I appreciate all of the great advice on this board and outside, but sometimes it's tough to make a call when you have so many different answers. Thanks!

rivercrazy
07-17-2001, 12:17 PM
That's for sure. Everyone has their own unique spin on things. The main thing is to keep you motor together so you can have more fun!

Racing Ray
07-17-2001, 03:14 PM
.
[This message has been edited by Racing Ray (edited March 12, 2002).]

Chestah Cheetah
07-17-2001, 03:18 PM
Ray, if that's the case, would I see oil leaking? Cause I didn't notice any.

Racing Ray
07-17-2001, 04:43 PM
.
[This message has been edited by Racing Ray (edited March 12, 2002).]

Craig
07-18-2001, 03:38 AM
A standard rule of thumb I've always heard was 11 pounds of pressure per 1000 rpm.
Craig

Chestah Cheetah
07-18-2001, 09:14 AM
Thanks Ray! I'll check that tonight.

sea buddy
07-19-2001, 04:36 PM
stock 454 merc/chevy no spec pressure at idle, and 20 or higher at 2,000rpm. I've had 14 454 or 454 magnums over the years . At 2,000 rpm Low reading was 30 , highest was 65 psi, hot. Never ran any of them over 4,000 rpm for more than 3 minutes. Never lost a motor.

Chestah Cheetah
07-19-2001, 10:17 PM
I'm in the process of changing the oil to a straight weight 50. It's been draining for 4 hrs. and I've got almost a Sparkletts bottle full. Let's see if this oil does the trick.

Chestah Cheetah
07-23-2001, 09:58 AM
I went with 40W instead on 50. Pressure ranged from 24psi at 3000 rpm to 36psi at 4000. A little better.

BLOWNDRAGBOAT
08-08-2001, 03:09 PM
Fatrat....I am running a blown 632 in my dragboat and @ idle I am running 40 pounds of oil preasure and 110 pounds @ 6000 rpm. I am running REDLINE racing synthetic. While this is high for most BB chevy's, most of the engines I build for customers range from 468's to 638's most of which are 540's. I haven't gotten anyone to let me build a 705>>>YET!!!!! anyway, my customer engines are set up for 30 pounds @ idle when the engine is at proper temp and 60-70 pounds at 5500rpm. This will fluctuate depending on oiling system. I would JUNK an electric gauge on ANY engine worth keeping. I have seen a ton of sending units go south. Go with a mechanical gauge (I prefer autometer over gaffrig) and make sure you plum in a low preasure sensor and hook it to one of autometers warning lights. I normally do this on all my engines and set it go light up when oil preasure drops to 25 pounds. Hope this helps.