No Pressure
 

OK, I am at my wits end. My truck is/was at a point that the “builder” motor that I was running was underpowered for what I wanted. I went out an found a nice high nickel 4 bolt SBC block and sent it to one of the best engine builders around. I had it clearance for a 383 crank and bored .30 over. Scat rotating assembly putting it to @ 10.1. I then put on a set of AFR heads with the same shop doing a 3 angle valve job to freshen them up (even though they were never raced) I am running a Comp XS282 Solid lifter cam. I also put in some Howard Cams EDM lifters (91118) and 8/200 push rods. Melling M55HV pump with a 7 quart pan. The pick up is a bolt on from Kevco and is 3/8” from the bottom of the pan. I plastic-gauged the crank bearings and they were all within tolerance. If any thing they were a bit tight.

After using Royal Purple breaking for @ 30min I drained the oil and replaced it with Lucas 20/50. When I fire the motor it has between 25 and 30 lbs of pressure cold. After getting up to @ 180 deg the pressure drops to almost nothing! If I drive it around the block the pressure comes up a bit (12 lbs. at 3,000 rpm) but no where near what I would call safe. The engine temp never gets above 200. I swapped the distributor and nothing changed. I tried a different gauge and nothing changed. I probed down the oil gauge hole to double check that the main bearing had the oil plug in place and it does.

Thinking maybe I should ditch the EDM lifters for traditional ones as one last Hail Marry. Other than that I guess I have to pull it. First I would check to see iff the 3 oil plugs behind the timing gear are there… then take a look at the oil pump to be sure the relief spring didn't stick.

Anyone with other suggestions before things get out of hand $$$?

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What was pressure during break in period?

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The engine sounds like a very nice combo. If it was me I would try another oil pump, especially if I can get the oil pan off fairly easy. You could have gotten the .01% defective oil pump. If nothing changes with another oil pump then it must be the lifters. I have never used EDM lifters but I can't believe they would lose that much oil pressure. Good luck.

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Electric or mechanical oil gauge? There are different sender ranges for the electrics.

IIRC -some(all?) SBC blocks have a 2nd oil tap part way down the drivers side toward the oil filter.

Double check the little threaded piece the oil filter screws onto. The install torque on those is in IN/lbs not ft/lbs. I know from experience that ft/lbs will crack that piece.

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I'm sure you've already thought of it and probably done it but you could replace the oil filter with a different brand. It's the cheapest and easiest thing to do.

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Break in pressure was @12-15 @ 2,000 rpm
Gauge is mechanical
I will inspect the pressure valve between the filter and block

(IIRC -some(all?) SBC blocks have a 2nd oil tap part way down the drivers side toward the oil filter.)
Could you describe in more detail? Maybe a picture?

This is an internal tap right? I have zero external leaks.

Don't know if I can drop the pan w/o pulling the motor. I can give it a try...

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Yeah... on my 3rd filter.

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there is also a core plug under the rear main cap that if not reinstalled will cause oil pressure issuses

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This is the plug I verified by measuring down from the oil pressure gauge hole

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Here is a trouble shooting guide from Melling.

https://www.melling.com/aftermarket-...u-k/technical/

I'm not an HV pump guy but I do like the Z/28 pump from Melling. I tried to find what the pressure on the HV pump is supposed to be but didn't easily. It ships with two springs and you get to choose high or standard pressure, correct? And I assume you have the high pressure spring installed?

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Something I ran into years ago on a motor I built....

when the machine shop installed the cam bearings, they failed to get the rear bearing all the way in to the proper position....

there is a radial groove under that bearing where oil goes up around it and the up into the lifter galley......

if that groove isn't covered by the cam bearing , most of the oil will just pour out there and run back into the pan....the motor would run, just didn't have much oil pressure.

not saying that's your problem but it happened to me.

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MikeC: yes I used the high pressure spring.

A1971 Blazer: Right now I am considering dropping the pan w/o pulling the motor as one last attempt to not disassemble everything again. If successful I should be able to see that bearing...Thanks for the tip

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I dropped the pan enough to get to the timing gear. Once I removed it I found the center galley plug was not there. I took this picture showing it was missing. When I went to send the pic to my machine shop I noticed that the plug was between the crank gear and the block!!!! I think it came out during break in and the sprocket wedged in it there. Had to use vice grips to get it free.

The plug is marked 9/16 and the hole is not tapped. I don't want to tear down the engine so tapping at this point is not what I want to do. I don't think I can tap it without getting shavings into the cam.

I am disappointed that the machine shop only tapped one of the three holes. But thats water under the bridge I guess.

My question now... is this the correct plug and it just wasn't installed correctly?

Am I asking too much of a press in plug with a High pressure pump?

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May sure its right plug knock it back in and the use a chisel to stake it in place

Yup. That would do it. Those front holes are not threaded from factory. The plugs are pressed in then staked in place.

More specifically. Threaded rear galley plugs are removed, front ones driven forward & out with a long rod, stake marks & distortion removed with a tapered reamer, and new front plugs are staked in place again. High pressure pump will NOT blow them out if proper procedures are followed. All this is SBC rebuild 101.

To be honest the work I see in that image looks shoddy as hell.

As for the high nickle thing. Hope somebody did not convince you to pay extra for a "010" cast block.

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Thanks for the feedback. Googled staking the plugs but didn't get a real good description of the process (tools, where to strike, etc.). Just a few pictures of the marks left behind. If you could describe the process in detail that would be a great help. As for the block, it is one that came out of my son's Camaro a few years back. Also wondering what else looks "shoddy"? I read that it would be good to take the lone threaded plug out and drill a small hole in the center... opinions on that?

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Just a good chisel and knock a couple places around the edges

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You just want to peen the metal out bit to hold it in place

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Here is what I found on staking the plug. Some seem to stake the block only, some the block and plug. My guess is it depends on how deep the plug is. Any tips would be great

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Truckdude, thanks for the comments... was writing my response before I saw your input

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good you found a problem .

little story i was told by a old retired vo-tech school teacher .

kid in his small engine class built a sbc at home and it fired up o.k. but no oil pressure and clattering lifters . told him check this / this / and this . if it didnt change bring the engine in class we will tear it apart and find the problem .

well he had to bring in the engine so he could figure out the problem . :smoke: lets just say they found the problem as soon as the oil pan come off . the oil pump pickup was FULL solid with blue rtv and there was atleast 3/4 of a tube worth still in the pan .

the kid used so much rtv he ozzed it in the engine and the oil pushed it all down to the bottom of the pan till it plugged up the pickup and almost got to the pump .

they tore down the engine and re-sealed it correctly and fired it up with 100% perfect results . :lol:

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This would be a great thread to list in the tech how-to section.

It clearly answers questions like...
What about that hidden little plug under the rear main cap?
Do I really need to stake the three front oil passage plugs?
How do I stake them right?
And is there any advantage to using screw-in plugs in those front three oil passages?

Really clear Q&A in this thread.

Cheers to all of you guys!