Hot Rods "New" small block oil pressure

If it was broken in on a dyno then 1. there's no need to prime it, it is already primed. And 2. the dyno shop should have recorded oil pressure readings while it was on the dyno. Check with them. If there was a low pressure problem it would have been found at that time. You really think a dyno shop is just going to ignore an oil pressure problem?

 

I wont use those plastic lines, they are terrible, too small, and they are stretchy, so they tend to absorb pressure fluctuations rather than pass them to the gauge. I use a 1/4" copper tube, the gauge will respond to oil pressure changes much more quickly. Moroso actually used to sell these as a "quick response" kit, but I searched their website and Summit, they dont seem to make it any more.

 

out of sight , out of mind , and "think they should" is the variable of your equation , easy way to put a example what happens when you have air in your brake lines ??? well the wheel cylinder is the gauge

 

Wow! This thread got scientific quick.

 

When you have air in your brake lines, you can push the pedal until it hits the end of it's travel, and it stops building pressure. That's why the brakes don't work when there's air in the line. But if you put a pressure gauge on the end of the brake line, it will show the same pressure as there is in the master cylinder.

When you have air in the oil pressure gauge line, the oil keeps flowing into the line until the air in the line is all at the same pressure as the oil...the air will compress some, but once it reaches the same pressure as the oil, it will stop compressing, and transmit the pressure just like a liquid. And it makes the bourdon tube work just like it does with a liquid, it doesn't know the difference.

 

On my old 283 at full speed i was getting 30 psi of oil. And at idle it was at like 15. Never had a poblem. But to prevent opening up stuff and tearing into the motor just try a new gauge. I run 2 gages on my motors the stock in the dash and a after market one. Goodluck

 

No paperwork on the rebuild.
Can you find out EXACTLY what the guy put in there, new ?
I'm reading about a missing plug, etc., but if the guy wasn't in the area of the plug (depending on what he installed), you may be pulling oil pans, transmissions and timing covers for no good reason.
A rebuild in a professional machine shop may include A to Z, but maybe this guy did less than A to Z.
Not a sin, no finger pointing to the guy, just get honest answers from the guy, as to what he did or did not do.
Make a list of what he did, then post that info here.
Another thought.
Did I read where you stated the dizzy was loose or popped out of place (vertically) when you started the engine ?
Did the dizzy loose its connection with the oil pump, at that time ?

 

Air in oil line will still show the correct oil pressure !!!
Make sure line is not crimp off ,
Try a different Guage , it always good to have several test tool to verify when you run into something suspicious ,,
Also check to make sure on yr dizzy is at the correct depth.. If to high or low it can bleed off oil presser , even on a stock dizzy ,, Still Low presser ,check to make sure none of the Oil galley plugs have fell out or missing under Timming cover on front of block , ( will cause low oil presser ,
I had a motor that had 2 pds at idle and 30 @ 2,500 RPMs
I drove it for 50,000 miles ,
Rule of thum 10 pounds for every 1,000 rpm Race engine
MAKE SURE YOU USE OIL WITH ZINC OR ADDITIVE!!!

 

Sounds like a weak suck oil pressure bypass spring or bearing clearances too big. I bet when that sucker gets hot he won't have shit for oil pressure. I would have had the pan off already. JMO Lippy

 

X2 on this allso

 

no the brakes do not work as your trying to compress the fluid and instead the air is absorbing the pressure by compressing , remove the air ( compressible fluid ) and the fluid behaves as a solid and will push the cylinder cups out

plain and simple air bubbles in the line will dampen any fluctuations or absorb any pressure by compressing ( squeezing it ( air bubble ) into a smaller space ) and give you a error in the reading,
the law of hydraulics , Pascal's law or the principle of transmission of fluid-pressure (also Pascal's Principle[1][2][3]) is a principle in fluid mechanics that states that pressure exerted anywhere in a confined incompressible fluid is transmitted equally in all directions throughout the fluid such that the pressure variations (initial differences) remain the same.[ air is considered a compressible fluid , you can decrease its volume by compression and it will rebound to its origianal area when uncompressed

 

Ok, I give up.

 

Squirrel , some just donot know things work opposite of laws !!!

Smoky Yunick said that he was always Desprovean what books of physics said where not possible!!

 

I'm not giving up on the laws of physics...I'm just giving up trying to explain how they apply to this situation.

One thing I've learned over the years, is that folks like to stick to the stories they believe in. Facts are not very important.

 

I go around 2X, prime it every 90*.

 

I am going to try to get a hold of the guy.

This does beg the question.... Why does the oil bleed back out of the line to the gauge? Bet if I got out there right now it's almost empty

Don't know if this is normal but I can't put two hands on the harmonic balancer pulley and turn the motor with plugs in. I figurehead it's normal cause it turns over super easy with the starter. I just used to put a little tension on the belt on my 235 and use the fan blade for leverage to turn the motor with the plugs in and was shocked that I couldn't do something similar here. Although I don't have the fan blade and it makes a difference. With the plugs out it turns over easily


I used Brad penn oil. Has a lot of zinc I think 1200ppm

 

You should not be able to turn a fresh Chevy V8 by hand by only holding the damper, especially with the plugs in. When assembling an engine, I find that after I install about half the pistons, I can no longer turn the crank by just pushing on it, I need a lever.

The reason the oil comes back out of the line to the gauge, is because the gauge and line are full of air. The air compresses when there is oil pressure, then when you stop the engine and there is no pressure, the air expands again, pushing the oil back out of the line. It's all perfectly normal.

 

How come no one ever considers that if the factory set the idiot light @ say, 10 PSI, you probably don't need a whole heck of a lot more than that, @ idle? If you've got more than 10 @ idle, you're good. More than 30 @ 3,000, you're good. If you don't check your oil pressure, how will you ever know if your motor is ok. And running it for 45 seconds IS NOT checking your oil pressure.

 

Drew,
Remember from C.T. discussions, turning the engine with the fan blade on the ole sixes could be hazardous, because of those old fan blades fracturing under pressure, from rotating blades by hand, then the blades coming off like a missile.

 

I've never bled an oil pressure gauge line and have never had any trouble. In my book psi is psi be it air, water, or oil. I had an engine once that only had 5 psi at idle when it was warm and 30 psi the instant you gave it some throttle. It was a cheap triple mini-gauge set that I bought for $5 at a swap meet. I was concerned at first so I pulled the valve covers to see if oil was getting to the rockers. It was and that engine is still running good today. I think you are over analyzing a problem that you don't really have. Put it together and drive that thing!!!

 

Keep in mind that "oil pressure" just ensures there is adequate supply of oil to the oil galley's supplying oil to all the critical points in the engine. The pressure itself is not what provides protection, the protection is provided by the oil as it is trapped in the bearings and other points and it lifts and separates the parts. I could get into theory's of lubrication regimes such as hydrodynamic and elstohydrodynamic and border and mixed film, but I would probably bore the crap out of you; but basically any pressure at all means oil is present where it needs to be. Pumps supply flow, not pressure. Pressure builds as a result of restriction to flow. If there is ANY pressure at all, there is sufficient flow to exceed what can be used by the system.

Uhm, I better add, I'm not saying it's OK to run with extreme low oil pressure, just mentioning some basics of lubrication and fluid dynamics. I think sometimes people think it is the 10 - 60 psi of oil pressure that is keeping the bearings afloat. The actual pressure in the bearings between the journals and the bearing surfaces is much greater than that. At the point of contact the oil is trapped between the 2 surfaces, it can't flow out fast enough to escape, and as the force of the 2 surfaces trying to come together increases the pressure on the oil goes way up. In a pure rolling motion, such as in a rolling element bearing, the actual pressure between the surfaces can exceed 150,000 psi. It's much lower in a sliding motion plain bearing like we have in engines, but it's still far greater than 10 - 60 psi.

 

OMG the guy asked as simple question! I wonder if NASA has a discussion board..... H.A.R.S..

 

I'm suspicious of anything coming from Autozone. Get a good gauge and check it again.

 

Yes, we sometimes forget that this is the HAMB, and some guys start to think guys actually want meaningful, well-thought out answers to their tech questions, instead of a steaming heap of rod-abilly bullshit...
So guys, try to stick to mono-syllabic words when posting a response, and dont explain anything in depth. It makes some guys feel stupid...

 

reminds me of a OIL (plastic) line we had one time...
it would ALWAYS fill up upon start and go back down when turned off....
10psi is pressure as long as it NEVER goes BELOW that EVER...but
when revving the RPM's up... so should the pressure FOLLOW.

 

X2 and if it's a brand new cam you need to break it in properly or that oil pressure problem will be the least of your worries.

Pat

 

You

should use solid metal line for that, Jim.

 

Until Drew posts back, it is not known if there is a new "anything" on his engine.
With no "paper trail", Drew must rely on the seller of the engine to be upstanding.
However, if, in fact the engine was on a Dyno, there has to be paperwork.
A Dyno report is not something you wad up and throw away.
I think a Dyno report would be a heck of a tool, when selling a quality rebuilt engine.

 

Lots of talk about oil pressure which should be an important feature of installing a new/rebuilt engine but often is misleading. For example, I purchased a new Edelbrock Signature Series engine and the oil pressure at idle is never more than 10 pounds when hot which bothered me. I talked to Edelbrock tech's and they told me that was fine as their testing resulted in better oiling than with high idle pressures. I have 40K on the engine with no problems. Ten pounds when cold would indicate a problem — per Edelbrock.

 

How much oil does it to move a gauge from 0 to 100lbs maybe a drop or two. How big a line is needed? Metal lines can vibrate and break plastic can melt take your pick. A general rule I follow 10 lbs oil pressure for every 1000 rpm.