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Discussion Starter #1
Background:
When the machine shop built my 406 they used a m77 standard volume pump. I needed to use a BB pump due to the .75" p/u.

I know that the clearances were correct when the engine was assembled. The pressure really hasn't changed from when I first got it running last winter.

Pan is 7qts plus the filter!

Hot at idle it has 20-16psi, 35-38psi at 2000rpm going down the highway. At WOT it goes to 40+psi, and thats it.

The problem I believed is somewhat based on the fact that we used direct lube/cool run solid lifters. each has .020" hole which equates to something like a 3/8" hole, or internal oil leak.

the last engine/pump was an Hv and went 55psi at 3000rpm, but the clearances in that 383 were big and idle was equally as bad and that was w/o the direct lube style lifters.

My question is; how much is enough? I have heard some factory manuals state 9psi at idle for stock sbc, which this really isn't.

I am considering putting in a HV/HP milodon 18760 BB pump. But of course this entails major surgery of removing the entire engine and the car is running nearly perfect!

Any info or suggestions are appreciated. SS
 

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I've always heard you need 10 psi per 1000 rpm. This is from professional engine builders, not my cousin Bubba Ray. :D

First thing I'd do is verify the accuracy of your oil pressure gauge. I've had them go bad on me before.
 

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It looks good except for the WOT part, that might be a little low. My' 69 is below 15 at idle hot. With all you've done I hate to ask but has the gauge been verified to be accurate. My '67 has a HP pump and shows it on the guage and the '69 has a HV pump which seems to show it in terms of leaks. I'll go stock pump next time for sure.
 

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Discussion Starter #4
I put a pro comp guage on when I primed it on the stand, and it read only 34psi from my craftsman 1/2 drill. So to answer the question not in the car as a direct comparison.

It would be easy enough to do though since it is a -3 braided line, a good idea that I will probably try however, I think the auto-meter mech guage is good that is in the car. From what I was told the spring in the pump could be the reason that it won't exceed around 44psi. Not sure but either way pan needs to come off.

I have considerered trying the swap in the car but, with a scattershield and a block plate, I don't know if that is even possible. Probably less of a headache to remove the whole thing. Total PITA, and of course there are no gurantee that pressure will increase dramatically. As far as oil pressure goes it seems to be a curse for me!
SS
 

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I don't understand why you used a big block pump.

That is very old school and is OVERKILL oiling on a small block Chevy.

A good M55 pump, hardened pump shaft, a good oil pan with the matching pick up and proper bearing clearances should be more than adequate.

You can over oil a small block Chevy.

Advances in oil technology have come a long way since the 60's, 70's and 80's with new racing blends ans synthetics.

JMO :D
 

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Discussion Starter #6
I needed to use a BB pump due to the .75" p/u

Milodon road race pan uses a specific p/u that has a .75" inlet and bolts to the pump, if memory serves the body of the small block pump differs.

You can over oil a small block Chevy!


That is why the machinist/builder decided to use the standard volume M77 was worried about too much pressure and volume, something to the effect of washing the bearings.

I guess this is the real meat of my question, at lower pressures are the internal parts getting the appropriate volume(amount of oil) regardless of the pressure?

From what I have been told, BB pump is better in terms of pressure variances and distribution but that seems to almost be opposite in my case.

SS
 

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There are stock volumn pumps available with the .75 diameter inlet.

What are your bearing clearances and rod side clearances?
 

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Motorhead62 said:
There are stock volumn pumps available with the .75 diameter inlet.

What are your bearing clearances and rod side clearances?
Side clearance does not regulate the oil flow its the bearing clearance as we run some piston guided rod engines with almost .100 side clearance and these engine run the same oil pressure as the rest of the engines we build.

I would maybe look at a cam bearing issue some times the rear cam bearing does not get put in correctly or even may have spun cam bearing as we have seen both of these problems brfore and we have run lifters with EDM holes in them before M55HV pumps and no problems and the pump your uising is HV type pump.
 

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not to try and give stupid input
but i switched from 10w-30 to 20w-50
and the oil pressure went up from 5 at idle to 25 and 40 max to 55-60 max
might help
 
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