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Discussion Starter · #1 ·
First I know there’s lots of posts on this but I can’t find out why.
stats. 350, 60 over new everything. Forged crank, pistons , H rods, afr heads( 210cc flow)
total seal rings. New oil pump, it’s a shark tooth style hi pressure and volume. The motor is meant for just drag racing.
mains are at 0.0010
Rods are at 0.0010.
oil galley in front has been taped and Allen caps installed. The plug at the bottom of the oil pressure line is there. Running a dual remote filter system (earls)
Prime the motor and it has 35 psi
Start and run for 5 minutes and is at 20 psi , does go up when on the gas.
So my question is where is the pressure going?
no lifter noise ( does have a solid lifters)
No knocking.
gauges are new also I run a dummy light.
 

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More for Less Racer
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20,173 Posts
Agree with Johnsongrass1, filter change is first troubleshooting step.

Was the bypass in the pump removed and checked for trash in the bore and checked for free movement with no sticking??
Bypass might be stuck partially open...
What's the pressure at 5000 rpm?

Any new pump should be dissassembled and checked over before use.
 

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1949 Ford Coupe RESURRECTION
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20 psi at idle? When it goes up, how far is up? What is it at 1500 rpm? 2500 rpm? Is the gauge accurate? New doesn't necessarily mean accurate. Check its calibration before getting worried..

Let us know what you find
 

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Weight of oil, temperature of the engine, RPMs at the indicated pressure is necessary information.

Pressure varies by RPM so where it goes at what RPMs is important information.

Rod and main clearances are awfully tight, at .001 what gives here, are you sure about these?

Gauges being new doesn’t assure accuracy. Are they mechanical or electric? Same gauge used for priming the oil system as used when firing the engine?

Bogie
 

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First I agree that rod and main clearances are too tight for a racing engine. Usually racing engines are built with looser tolerances and that is tight even for a street engine.

What oil pressure does the engine have when cranking?

Could the high volume pump be sucking the pan "almost" dry and most of your oil be up in the top of the engine? Does it repeat the scenario of higher pressure upon start up and then dropping later, or did it do that the first time and then just stay at the low pressure from then on?

What keeps your bearings cool is flow. Even if you put a high volume pump on it, it cannot flow more oil thru the bearings if the clearance is too tight. All of your clearances are basically "orifices" that let oil flow. Smaller clearance = smaller orifice=less flow.............so your pumps excess flow is bypassed and you gain nothing. The flow may however go thru the other clearance/orifices that have less resistance. Here is one of my favorite videos.

and another one

 

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1) rear camera bearing not installed such that it covers the oil groove.
2) pressure regulator Piston stuck in the bore allowing oil to bypass all the time. If it's stuck it will have normal pressure if you rev it up
 

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Google "Tunnel Ram 406"
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Replace dist. You may not have proper seal where oil passes to the lifters.
 

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Member - AMC/Rambler "guru"
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20 psi at hot idle (engine fully warmed up) isn't really low. The real issue here is how much does it go up at rpm? The old rule of thumb is 10 psi per 1000 rpm, which would be 30 psi @ 1000 rpm (idle at 600 or so), 40 @ 2000, etc. Modern engines usually have more than that though. At 3000 rpm it should have about 60 psi, though 50 would be considered adequate.
 
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