Technical No oil pressure on fresh rebuild....

I had the same problem when I started my built 383 Mopar in the Stude following a complete rebuild (it was also primed very well before firing).....Called my late Uncle (was 92 and a mechanical genius) and he immediately told me the problem over the dad gummed phone!! He said the rebuild lube, grease etc had stopped up the new filter......changed the filter and presto pressure went from 20# to 45#....Experience is worth a lot more than an electronic machine most of the time.....Also on this note, I had been using a Fram filter and one day noticed how small the openings were compared to a matching # Carquest....put the Carquest on and litterly raised the pressure another 10# at highway speeds..........Joe

 

We can, of course, ***ume that you didn't braze the pickup tube to the oil pump without dis***embling the oil pump and removing the spring, right? That you have calculated the extra number of quarts of oil needed to compensate for the larger oil pan. That you didn't use a piece of **** Fram oil filter. That you pre-lubed the oil pump. That you didn't leave a rag anywhere inside the engine. That you know for sure the cam bearing holes are lined up properly. That you located the pickup tube properly with the clay test, and made sure it was secured, to remain in place, by some means other than interference fit, or that the pickup tube used was as specified for use with your particular oil pan? What have I missed? (I know I am restating many of the suggestions and questions that have already been posted, but a check-list is important in detective work.) And, I know from bitter experience how it feels to be humbled by a simple failure with so many possible solutions. And, of course I have not touched on clogged oil p***ages in the block, possible kinks in the oil pressure lines, and camshaft issues, or other items such as the filter byp*** valve, and what appears from other posts a whole minefield of potential causes that even when minor can cause serious problems. The bright side of this whole, irritating process is to realize how important it is to have a good machinist who checks every step of their work, and verifies all the elements that fall under their purview. I know you need another poster to wish you 'Good Luck' like you need extra holes in your head; but I'll do it anyway. Good Luck, not only on solving your existing problem but for all the others that may come along, and that you'll manage with a smile. Yeah, I know. The smile comes when the gremlins are all lined up ready to be buried.

 

Oh yeah, Smokey Yunik's rule of thumb was ten pounds of oil pressure were necessary per thousand rpms. And, common sense says, too much oil pressure is as bad as too little --- on account of the issue of gaskets and seals are not designed for extremely high pressure.

 

It gets under my skin a bit when someone says ; gaskets & seals can't stand up to high oil pressure. .... save oil filter/adapter or an external oil pump , there are no gaskets or seals designed or intended to handle oil pressure...... now oil volume , that's a diffrent story...
dave

 

A little late now but you could try heavier oil or a heavy additive like the original STP to see if it raises the pressure much. With it open now you could connect air to it to see if you can hold pressure or hear where all of the air is leaking out. You might be able to borrow or rent a priming tank that injects oil into the engine.

 

Check the notes in the overview from the Summit catalog where it says it primes the pump only. Some of these rods will fit into a distributor housing so they can be used to prime the engine.

 

I almost forgot about the fuel pump pushrod. If you aren't using the mechanical fuel pump, They make the nice chrome block off plates but don't always tell you that you need the pushrod in there to keep oil pressure up.

 

I've run a ton of chevy's with no fuel pump pushrod, never had a problem!! Better pull the bottom end down sounds like.

 

Check the pickup location against the bottom of the pan. Pickup too close will cause this. You also said you had a bolt-on pickup, did it have a gasket between the pump body and pickup tube like a SBF does? Gasket missing will cause this, too.

Screw a mechanical gauge directly into the block. Make sure your gauge line isn't kinked or broken anywhere.

Mechanical or electric gauges tried?

SPark

 

Yea I agree , I primed mine on the stand without a pushrod and got 55 psi.....

 

Here's what I read, "splayed mains"; that tells me this was NOT a stock block, and was possibly a race block that MAY have oil restrictors in place of the rear oil p***age plugs. Yes or no? BUT, if the cam is hydraulic, that would have surely made for a LOT of lifter noise. Bigger pan means more oil, I'm guessing you've addressed that. True that the oil galley needs a distibutor shaft housing to fully get oil throughout; the correct style primer tool is available, but the last time I had one, it actually got STUCK in the block; make one out of an old distributor. Priming the oil pump has never been an issue for me, though I've read you're "supposed" to do it. You also said the block was "clean", as in hot tanked/shake and bake, or just a fairly clean block? Sometimes machine shops don't always replace ALL the plugs, or do it correctly, if they pull them before tanking. I'm a little lost however; you had it "running" without lifters making a racket, but low oil pressure? I'm leaning towards the gauge based on that. Keep us posted. I am Butch/56sedandelivery.

 

I am no mechanic, but recently had low old pressure on my rebuilt 472 it would not prime.
The builder had forgot the o-ring between the pickup tube and the block, once I installed the missing o-ring, everything was good to go. your 327 does not have the same design but some of this info is the same across the board. Since you said you did not have prime to the front of the block but did to the rear I would not fret over the gauge yet, there is an internal problem.
*I would check pan depth in relation to the pickup should be about 3/4 of a inch between the bottom of the pickup and the pan. (did you put in enough oil?) 6qts? 7qts? etc.
* Clean and inspect the screen on the pickup also check for cracks in the pickup tube.
*I would then check or replace the oil pump
now prime the engine with a drill motor with the valve covers off, use some card board as a shield if it gets messy, run the drill for at least 30 sec, you should get even or full prime by then, it you don't, I think the problem is either a galley plug or a blocked p***age.
I always try to rule out the easiest things first. Pulling the intake would be next if the above ideas do not fix it.

Godspeed
MrC.

 

Wow, i feel so dumb.... I must have taken the plugs behind the timing chain out for some reason and forgot to put them back in.... Well that was easy!!

 

Good to hear!

I'll bet you are relieved!

 

I might be relieved, but I sure feel dumb

 

Make sure you distributor fits nice and snug in the block. My friend bought an after market dizzy and when he started it up he had low oil pressure. Put the old dizzy back in and oil pressure was normal. Long story short, the aftermarket dizzy was machined too small and caused low oil pressure . Look at a oil schematic and you will see how this can happen.

 

Glad the OP got his problem fixed. Just FYI. I didn't see any body mention that the oil system is timed in an SBC. You will not get oil through all push rods unless you turn the motor over while turning the pump.

 

I use a priming tool made from an old distributor and spin it with a drill while turning the motor over with the starter. If it's on a stand and doesnt have the starter on it then i turn it with a long breaker on the balancer bolt. Pressure it up before hitting the starter.

 

At least it was a "cheap fix". Good to see that the problem is solved.

 

Dumb is not as bad as the alternative. You could have just gone racin and ruined some chit.

 

good evening, my first post,
glad the solution has been found,

can someone explain how the oil system is "timed" please,
also, has anyone got an oil path diagram for a small block or explain how the oiling sytem works,
i'm working on a freinds 305 (1979, 460777 block)
the first V8 i've ever worked on, so many things to learn.
quite a change for a 2 stroke engine man.
regards, david

 

Here are a couple of diagrams for you. The second is pretty simple but between them you should get where you want to go.

I don't know that the oiling system is times, at least not like say an old Harley Engine has timed oiling. The system is a constant flow system. The distributer is required to be in place to correctly oil the top end, and on some of the older engines (pre '60) the distributer had to be clocked properly but anything newer than an early 283 would not have that problem.

 

Not dumb, you were smart enough to see the problem.

 

The rods only get oil during half of the crankshaft revolution unless the crank is cross drilled or you install fully grooved main bearings. Turning it over while pre-lubing makes sure each rod bearing gets a good squirt of oil.

 

Well, look on the bright side; at least the timing chain/gears got adequate break in lubrication. I've heard of some drilling a tiny hole for lube in the centermost of the 3 front oil plugs to help with chain oiling, but never heard of anyone accidentally leaving them out. It's on my double check list now. I am Butch/56sedandelivery.

 

I cant believe I did it, I must have pulled them back out to double check the front main p***age wasn't blocked in the middle plug and forgot to put them back in. I've been working 12+ hour days, then afterwords wrenching in the cold so I'm ***uming it must have been one of those nights

 

Thanks for telling us what you found. It's easy to do when you try to juggle too many things. When I work on an engine I'd like to be in a locked room with no telephone.

I've seen a Pontiac engine where the nylon timing gear failed and the pieces got into the oil pump byp*** raising the oil pressure high enough to cause the oil filter to fail. A Baldwin filter was installed and that held enough pressure to pop a drive in cam plug out. The p***ages were tapped for threaded plugs.

 

I thought the same thing Spinout. Check the clearance between the pump pickup and pan clearance. Might need some modeling clay. Yep sounds like a long weekend but check all the easy stuff first. Oil filter etc. Could have some problems in there or some weird trash or **** up in there.sorry for you bad fire up hopfully it isnt ruined inside,yruhot

 

Glad you found the problem. I've primed a bunch of Chevy sprint car engines using an old distributor shaft with the teeth ground off the gear so it wouldn't catch on the cam gear. I never needed a distributor housing or a fuel pump push rod, so I hunted up a schematic of the Chevy oiling system. It's a pretty basic system and goes nowhere near the distributor or pump rod.

 

Done exactly the same thing on a 390 Ford FE