B Block Oil Presure

TK in LA

TK in LA

Well-known member
I know a lot of you are running "B" motors in your "A"s and I have a question for those that build 'em. The block I'm using was previously done in another car before it started leaking water. It has a full pressure oiling system, inserted mains and rods, Chevy valves, Winfield cam, Chevy rear seal and lightened flywheel. I've had the block vacuum brazed and also cracks pinned and the block was re-sleeved back to Std. . I also reworked the oil pump per Bills Bangers. The motor is also running an external oil filter and relief line to the front cam gear.(see pic) The problem I think I have is that with no head installed and turning the motor over with the starter I started to get about 20lbs of pressure and then it dropped off to about 5lb. I dropped the pan anticipating the plug I made for the pump had blown out but that was not the case. I put the pump in a beaker of oil and spun it with my drill motor (ccw) and I had lots of flow and couldn't stop the flow with my fingers (good pressure?). Could it just be that it isn't turning over fast enough or am I leaking oil internally? Before pulling the pump I had pulled the external line from the side of the block and there wasn't much pressure. I'm thinking I'm leaking past the top of the pump but not sure. Waiting constructive comments. Thanks!
 

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What are you doing to hold the oil pump drive gear down? With the engine out of the car, I can not see from your picture if the distributor is in place?

I see in a later post you have closed the oil passages at the top of the pump....never mind.
 
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Dave, the motor is currently out of the car with the head off. The picture was taken after the pan was removed and I removed the pump from the motor .
 
Correct. If the pressure is to high there is an adjustable pressure relief valve coming from the out port of the oil filter bracket that shifts the oil to the cam gear. I checked that and it wasn't discharging/open.
 
Have you tried backing off the pressure relief valve adjustment?
Have the original oil tubes to the mains been replaced? The originals are rolled from flat stock and can split open if the oil system gets overpressured, relieving the pressure in the wrong part of the system.
 
Thanks guys for the leads. Dan & Benson the pressure seems to be missing before the oil filter so it never see's the pressure relief valve or the valve cover. After asking my question, I went back and re-JB welded the top of the pump. It may have had an insuficient amount and was possibly one of the sourses of the leak. I can't get back to it today but will try on Friday to check the tubes. Thanks
 
Nice plumbing job, I like the Swagelok fittings. I cant answer your question, just a free bump to somebody that can...Good Luck!:)
 
I wish I could take credit for it but this was done before I acquired the motor. I had to replace one fitting and they aren't cheap.
For the others, if the tubes are bad, how do you go about replacing them. It may be obvious but I haven't looked at them yet.
 
I think that you are just getting ahead of yourself, and the engine isn't spinning fast enough to build much pressure. A full pressure B has very little pressure at idle, which is faster than what you are turning it with the starter. I don't know why the pressure came up to 20 then dropped off, sounds like the pressure regulator opened up???
 
TK

I am running a Dan 4 Banger pump. When cold it runs at 50-60 psig. I have to let the oil warm up before an serious RPMs. When he sold me the pump, he insisted on a Thomas valve cover because of the flexing.

Can you tell me more about the relief valve you are using? I have a smaller external one. It looks like the one you are using will pass more oil.

Bill
 
Jim, Thanks for the comments. I removed the pressure relief valve line to the cam gear and no oil present. Cajun, thanks for your comments as well. The oil isn't getting to the side cover yet as it first has to go through the filter. When I tried turning over with the line disconnected there wasn't enough pressure to move my finger off the hole. This is why I'm thinking it was the top of the pump by-passing the pressure or as Benson mentioned it may be the tubes. As for the by-pass valve it came with the rest of the parts. I could probably take it apart again and take pictures of it if you would like.
 
Check the filter that it is not a by pass instead of full flow, Seen that problem before on modern engines, ALSO go buy Jims new book 4- bangers & me ,Really worth the money, Its currently the HOTTEST A & B book out there,
 


Hi T-K


I was thinking the way the center cam brg get's oil, why would you close up the oil pump slot's...I'am running a full flow filter & installed a small pipe plug at the oil gallery...all the oil come's out the block's pipe plug hole to the filter...


I have plenty of flow..did you plug the original feed hole in the oil Gallery ? The way the oil pump feed's the center cam,,,unless the brg clearance is real big then the oil would dump out there



You should have plenty coming out the pressure line to the filter...


Just a thought,,


Greg out west
 
I ordered Jim's book a few weeks ago...read it cover to cover in one sitting and then went back and read parts of it agian. Good sound info...
 
Benson said:
I am puzzled by the oil pressure going from 20 down to 5 while cranking with the starter.

I also wondered about the oil pressure pushing the drive gear up but erased my post when I noticed that the oil passages on top of the pump were closed...

I am speaking of the "flats" on the very top of side of the pump (the flats that allow oil to go into the valve chamber) that are brazed up normally when full oil system is retrofitted ... not the oil outlets and not flats that allow oil to go down..

I also was thinking only about the oil pressure pushing the drive gear up against the spring.

Let's say that the distributor is not installed (with nothing but the spring holding the drive gear down).

Won't there be a point where the oil pump has enough resistance with cold oil where the spring is overcome by the the upward pressure and the drive assembly moves up and disengages the oil pump ... similar to camshaft "walk" with a weak or missing spring in timing cover?
Click to expand...

Bensen...You pulled me back into it...
My thought also at first (oil pump drive gear lifting) but we do not know how he is feeding oil back into the oil pump drive gear assembly. Specifically if he has restricted the opening from the oil galley (or gallery) to this gear/bearing area, the pressure would likely not build enough to lift the assembly due to the flow around the camshaft. If the opening was left wide open...I think it likely would lift acting as a regulator of sorts. I have heard mention the technique of staking the bearing assembly through the block...CAUTION: Pretty thin casting in this area...or using the distributor to hold the assembly down.
BUT..he states that he is getting no pressure to the valve chamber cover...so our theory is mute!
I have a B block I plan to modify for full pressure and I was going to study it tonight along with TK in LA's comments to better understand his current problem. Maybe the light bulb will go on...or not.
Good Day!
 
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Update:
Checked the internal oil tubes and they were replaced probably when the motor was first built for pressure and they were in good condition, nice and tight and no holes. New pan gasket installed and the pan is back on. As per some suggestions I took an old oil pump drive gear, turned it upside down and forced the drive gear down and while turning the motor over there was no change. I think I may be fighting two separate problems? One the motor isn't turning over fast enough as some have suggested and 2 there may be a leak in the side cover which may be why the pressure started to rise and then dropped as the gasket/side cover re-leaved the pressure. I'm at a stand still for now as I wait for the head to arrive but if I get the opportunity I'll try removing the side cover and re-evaluate the stock cover. Thanks for every ones help and suggestions. It's good to have second, third, fourth..... opinion. It may be awhile but I will update the post when I have it figured out.
 
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