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Author Topic:   Oil Pressure Problems?
redneck bubbas racing
Member
posted January 09, 2002 11:59 PM
I have oppertunity to buy a 377 short block for $300. Only 2 races since full rebuild. Sounds good so far right? Hers the problem- At start up it has 70-80 lbs of oil pressure, during race it drops to 40, and when he pulls in it goes to 20 at idle. The owner is a quaility guy, he pulls in when the pressure drops so there should be very little damage. This problem has been on going for a while now, he keeps rebuilding it with new parts and it keeps happening. He runs a solid cam and no resticters, could this be the problem? I also have heard that the oil galley can have a crack and cause this, anyone had this happen before? I run a very strict budget, one motor a year and it better be a cheap one too. Should I buy it?


jammin
Administrator
posted January 10, 2002 12:45 AM
What kind of oil is he using?

jammin


hughes
Member
posted January 10, 2002 08:52 AM
You might ask him what kind of bearings he used- cam/ mains. Did he use any special lube when installing them, what brand of oil pump/ was it new or did it come out of the corner of the shop with 100 races on it. Was the oil pump aftermarket high volume or stock and just stretched the spring. How did he break the motor in.

Hey Hendren racing engines this ones for you !! These are just some suggestions. REMEMBER Start out with the simplest solutions first. I have too many times assumed the worst and $300- 400 later it was a $5, $10 , $20 part.

sdhnc29
Member
posted January 10, 2002 09:24 AM
It's not uncommon for an engine to start with that high of oil pressure with cold oil . If your running a light weight oil , and using a B/B or S/B high volume pump , then you should be around 50lbs at full throttle with the engine up to temp . The old 10lbs per 1,000 rpm theory does not apply any more . Most race engines today will run a lower oil pressure than we did 10 years ago , high oil pressure is simply not needed , and only cost's horse power . For instance , our dry sump late model engines will have 50-55lbs at 9,000 RPM . Our wet sump engines will run the same .

The first thing that I would check would be bearing clearance , and side clearance on the rod's . Too much of either will account for lower oil pressure as the engine oil heats up and thins out . I'd also look for cracked main web's !!

As for no restrictors ; Unless you have a limited oil supply , small pan or stock pan , then restrictors are not necessary . You must keep oil on the valve springs !!

I'd want to check the engine and all the clearances before buying it . But for the price , you probably can't go wrong ! Pull the pan , look at the bearings , and if they look good then buy it . Then .... I'd pull it down and fix any problems that you might find , such as bearing clearance . If he pulled in with the pressure at only 40lbs , I doubt if it's hurt .

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Hendren Racing Engines
Rutherfordton , NC
(828)286-0780


6pack
Member
posted January 10, 2002 03:27 PM

6pack ,

It's not uncommon to see an oil pressure drop of around 10lbs when switching to the Royal Purple or the Mobil 1 . But to have your oil pressure drop to 10-15lbs while racing ......... something is wrong . You may very well be pumping your oil to the top end ! When we use restrictors , we install them under the rear cam bearing . The different sizes that my dad spoke of were , .090 for the drivers side , and .075 for the passenger side . The reason for the smaller hole for the passenger side , is to restrict more oil to the bank that gets the most oil anyway . Also , you can buy lifters that have built in restrictors , and eliminate the need for ***** in restrictors .

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Hendren Racing Engines
Rutherfordton , NC
(828)286-0780


6pack
Member
posted January 11, 2002 09:02 PM
I don't think the oil is the problem. I ran the kendall 20w50 all year, started out great, oil pressure was awesome. Mid year, we noticed that one night, the pressure dropped like a rock. Steel block, aluminum head, high dollar stuff (ie pistons, crank, rods, etc)
Didn't always do it though. Tried a couple different filter brands (normally run NAPA). Tried the Bosch Platinum, nice filter. Problem came and went when it wanted. Motor is now at engine builders, and hoping the problem gets resolved. Crank came back from crank shop "A ok". I will keep all up todate on what is found.

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RACERX


holeshot
Member
posted January 21, 2002 12:20 PM
Red Neck Bubba Check the bearings and if they look ok Replace the cam bearings. When you install new cam bearings clock them about one quarter turn and the engine will hold good oil pressure when hot.This will work very well.


bryanb30
Member
posted January 22, 2002 06:42 PM
Bryanb30 When you insall the cam bearings instead of lineing up the oil holes with the holes in the block turn them about one eight to one quarter turn out of line.The holes run from the mains to the cam bore when you clock them around it makes the engine hold more oil pressure to the mains when hot.This does not hurt anything at all.Make sure to center hole in cam bearing with oil groove in block.Use haveline or kendall 50 weight oil and you will be ok. We always have 55-60 pounds of pressure when hot and running at 8000 rpm's. I fill sure Bill Hendren knows about this and probley knows other ways too.From what i have read on his post you can take his advise to the bank anyday and fill safe about it.I will give you the clearance specks i use if you like .


bryanb30
Member
posted January 24, 2002 01:16 PM
My brother's car had a similar problem. His problem was a poor seal at the oil pump. He trued the edges and used red high temp sealer when he put his oil pump back on and it was fine (on the bolts too) . No more problems. Just a suggestion...hope it helps. Rino


marty
Member
posted January 29, 2002 04:53 AM
Hi redneck.One thing to make sure of is that the crank journals are inline & within tolerance & also that the con rods are sized as well.


Monster
Member
posted January 29, 2002 05:19 PM
I'll add one more thing to the pot here. Local engine builder had new engine wipe the bearings first night out. Customer brought it back, complained, builder rebuilt engine on his own dollar, same result on 2nd night. Customer's crew was doing final assembly on engine(heads and sheet metal), so builder redid the engine again, bought a 12 pack, and went to watch them put it together. Everything ok until crewman puts 12 quarts of oil into pan designed for 8 quarts! Big argument ensues, engine builder finally wins, drain 4 quarts out, no more problems! Crank was whipping oil into froth, oil pump was pumping a lot of air, which meant low oil pressure once motor had run for a few hard laps! I beleive he charged 'em for that second rebuild.


Eljojo
Member
posted January 29, 2002 09:31 PM
LOL!!! Seem like that if there is a way to ***** it up---someone will find it! Me included!


redneck bubbas racing
Member
posted January 30, 2002 12:30 AM
Well folks I bought the motor. I was replacing the solid cam with a very mild hyd. and decided to take a look in the pan. As I turned it over on the stand I heard a clink sound. Uh oh. After pulling the pan I found out what the noise was- One of the bolts in the oil pump was laying there. This is not the one that attaches it to the block, its one of the 4 that hold the cover over the gears. When I put it back in I checked the others to, they all were a little loose. Not finger loose but still could turn them with a socket and ratchet pretty easy. I then pulled a rod and a main cap. Bearings are pretty. The mains look brand new, the rod shows a little of the "dull gray" coming off but is smooth. Both journals looked real good too. Hopefuly it was a good deal. Hopefully I fixed the problem too. What do you think-Steve? Bill?


anson holley
Member
posted February 06, 2002 09:06 PM
Sixpack,i had a problem just like you had.Turned out to be a sticking oil pressure bypass.maybe changing oil was just a coincidence

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