tim72

Changed My mechanical gauge to an electronic gauge and found both gauges read the same. My car has about 44 psi when I start up and about 20 psi at idle. After it warms up it falls off to 30 at 3000 rpm and about 400 at idle. Starting to worry. Since the motor has restrictors I wonder if I am getting correct readings at the top of the motor? The restrictors limit the amount of oil to the top end. I can guarantee you I will never put restrictors in another motor. Also wondering if my oil pump is working correctly? any insight would be appreciated.

jeffreyalman

why would restrictors be good?

Lady72nRob71

400 at idle? Must be a typo... What would that value be and what weight oil are you using?
I am wondering about the restrictors also...

442Harv

Restrictors, only limit the amount of oil going to the top of the engine, so you don't pump the pan dry. This is only a problem when running the motor at high RPMs for a long time, like a boat, or racing. The oil pressure amount, is made by the oil pump, that pressure will still be at the bottom of the engine, and where you want it.What weight oil are you using? That 40 when running, os within factory spec. Correct the typo, on the low end, so we all know for sure what it is.

tim72

Sorry guys ! I am running 400 psi at 800 rpm (idle)

Just talked to a guy with an old Hercules 6 cylinder (Used in chris craft wood boats) motor which also during its day had issues with little oil pressure at idle. They adjusted the oil pumps to correct the issue. Discusing the engine with the builder this morning the clearances would have to be maybe 15 to 20 thousandths to have this poor of oil pressure. Bad lifter? Bad oil pump? It is possible that the engine builder did something wrong machining the motor but these guys have a very good reputation around Detroit. Nobody is perfect I guess. Just trying to kick around some possibilities. No rod knock and I run Brad Penn 20/50. Hope it is something simple or a Murphy's law. Lifters take about a minute to pump up at start of motor.

tim72

Restrictors are used in various Racing motors to allow for better flow of oil to your main and rod bearings. The top of the motor in most cases does not require the amount of oil the Mains and rods do. In the case of an Olds 455 some folks think there is a potential oiling problem to the lower end of the motor based on how the oil was originally designed to flow through the oil galleries. Thus the invention of restictors to divert the oil away from the top of the motor to where they feel it is needed most at the mains and rods. My opinion since I have had my motor rebuilt 3 times using restrictors is they are a PITA or not neccasary if you are running at approved RPM's. Most of these motors which probably were not taken care of very well in there day ran over 100,000 miles with out issues. Some guys take them apart at that mileage to find they are still in spec. The resrictors were designed for a guy who is running over 500 hp and shifting at 6500 rpm with his 11 second car at the track. Just my opinion! lol!

jeffreyalman

Tim is that 400 psi @ idle correct? That seems high right?

MN71W30

I shimmed the oil pump spring on my 455 the width of a 1/4-20 nut. I have 25 psi at a hot idle and 60 psi @ 2500 rpm.

80_cutlass

Many, many hours of use of 455 in a Jet-boat with out restrictors. The only thing that slowed us down was valve float aound 5500 rpm. Turned it 5k all day, sometimes for 2hrs at a time.

Never knew we weren't supposed to do it. Oh well.

sb

tim72

Geez rough week i guess. that is 4 psi at 800 rpm and 40 psi at 3000 rpm. It max's out at 40 psi no matter what rpm.

tim72

For some reason I had heard about a different spring in the oil pump. Can I ask why you had to shim the oil pump spring? Do you have the same possible issue I am having?

tim72

Sorry one to many zero's. that is 40 psi at 3000 rpm and 4 psi at idle or 800 rpm.

tim72

Wish I had left them out! I do like the bigger 7 quart pan and the high volume pump. What pitch prop were you running 21? Funny I have a 1956 Cal connel Cadilac that was set up to run at 5400 rpm. Most boats are 4400 to 4600 rpm. The boat does 55 mph. It had a dual Quad set up and roller lifters. Quite impresive for a 1956 Century Coranado with three inch through hull exhaust.

MN71W30

IMHO the shimming with a 1/4 nut seems to add around 30% to the pressure with a stock spring.

80_cutlass

Funny, we actually had a worn out jet drive...it would do about 25 mph @ 5k rpm. The clearances on the pump were way out of spec. But it was a 32 foot cabin cruiser, so it wasn't too bad.

sb

88 coupe

Restrictors only limit flow to the cam journals which are probably already restricted by the bearing clearances. Either way, the oil flows from the cam into the valley and back to the pan. Clearly not the reason for the pan to be "pumped dry".

In other words, those restrictors are a waste of time and money. Upside is, if they are already there, they won't hurt anything.

Best way to keep the pan from being "pumped dry" is to expedite its return with wider main and rod clearances (Rule of thumb = .001" per each 1" of journal diameter) to keep a high volume pump well supplied.

As long as that 4 PSI is not at 3000 RPM you do not have a problem.

Norm

jensenracing77

i agree with norm, i am no expert but if you have a good flow of oil at idle then 4 psi would not bother me.
welcome back norm.

MN71W30

You guys may be right but 4 psi would bother me greatly. What does it read after running down the highway on a hot summer day for 20 miles and you come to a stop? Thats just too close to zero for me. I thought the old oil lights went on below 7 psi. I'd try some 20-50 oil first and see what happened. It may be a defective oil pump. It may be a waste of time and money but I'd be pulling that oil pan faster than you can say oil pump.
Remember it's just my opinion!

jeffreyalman

sometimes ignorance is bliss - but that's exactly what happened to me a year ago in the 88 I was on the highway, 20 miles, got off and was stopped at the light at the exit and the oil light flickered - flashed on once. After I got over the effing shock of seeing that, I put it in N and never saw it again.

Checked oil, was fine on dipstick

Ignorance = not much in the way of gauges

MN71W30

LOL, you are so right!! Thats why my Dad never wanted to install oil pressure guages in his old cars. It gives you other things to worry about.

tim72

I have a 7 quart pan and use 20-50 Brad penn. So the oil is there and no way we will run the pan dry.
thanks for your comments.

tim72

Thanks for the information everybody. At least we learned something about our motors. A lot of smart guys on this list. I will keep you updated as to the decision I make and the effect on oil pressure. 4 psi at idle is in my opinion scary.

88 coupe

Thanks. Projects are still there. I just have less time on the personal computer.

Norm

joe_padavano

Once again, the restrictors that go in the feed holes between the mains and cam bearings do exactly NOTHING to restrict the flow to the top end of the motor. I encourage anyone who thinks that they do to take a good look at the oiling diagram that is in every copy of the Chassis Service Manual and don't believe everything you read in the Mondello catalog.

MN71W30

Are you talking about the restrictors?

I was going to comment on Norms post where he said 4 psi below 3000 rpm is fine. He must have had second thoughts and deleted it.
I had a 400 Olds motor with a tri carb many years ago. The oil light came on and I ended up selling the engine, it never knocked or ticked. I still remember the guy telling me a new oil pump solved the problem. You tend to remember the painfull lessons.
A few years back we had a 700 hp 540 BBC in a GTO that had a drop in oil pressure. We installed a new pump and we were back to more normal readings.
It's alot of screwing around and may or may not be worth the trouble or make any difference. A guy has enough things to do without looking for more work.
Good luck!

jensenracing77

i was thinking at idle, my Rallye 350 is around 6 psi at idle. i have around 10,000 miles on this engine.

380 Racer

You people play with some very scary oil pressures!!

jensenracing77

i can not say i am an expert at all. i just figure i must have good oil flow with this idle pressure or i would have had a problem by now.

tim72

Again thanks for your comments. The Motor seems to run fine but..... I think I will be doing some research onn the pump. I will probably pull the motor, check some clearances on number 7 rod and check the instalation of the pump. Ols performance has a pump that willincrease the pressure by 20 percent for $99. I think this is a small price to pay for peace of mind if that is all that is wrong.

380 Racer

I'll bet that pump from OPP is a stock pump with a shim behind the relief spring. Be careful if he tells you he manufactures anything or is an OPP exclusive.

88 coupe

Not exactly what Norm said. From post #16:

Norm

J-(Chicago)

And to think, I was bummed out when mine dropped to 35psi at idle.
The gauge lets me know when it's time for an oil change. If it goes below 40 the oil is getting too thin.
I admire all of the optimism in this thread.

citcapp

Since the day I built my 455 it has run 20 lbs at idle and 50 psi above idle after it warms up. What was the factory suggested oil pressure for these engines? Does anyone know? Lots of opinions very confusing for anyone trying to figure out what should be. One of the never ending threads I suppose

ziff396

Last year running 20w50 mine ran 40 lbs. @ idle hot 180 degrees. This year running 10w30 for winter (yet to change it this spring) it runs around 20-25 lbs. @ 800 idle hot. I am thinking of splitting the difference and running 10w40 this year. I have a high volume pump. 10w seams alot safer to me than 20w on cold start up and I have heard on other boards that heavy oil is not good with a high volume pump. Myself, I would pull the engine and check everything out to be sure that there is no damage being started before it may be to late. And yeah, definatly the oil pump. It's only one weekend but may save alot of $ later. Just my opinion.