Please someone help me! I have built dozens of small block Chevys but never had this problem. I have a 383 all new parts rebuilt. Engine is in the car , go to prime it and have NO OIL PRESSURE! I tore the oil pump out and replaced it but the problem persists. If I force air down the rear of the block where the sender goes it moves the distributor shaft so I know there is no blockage. There is also no oil being forced out of the engine anywhere. It’s obvious to me there’s a hole in the system somewhere that I can’t find . The rear galley plugs are tight . Does anyone have an idea what I’m missing! Thanks

 

Good thing: if they're loose, or missing, they'll spew oil all over the back of the flywheel.

​​​​​​​What about the front ones?

 

the block was professionally done . Not that people don’t make mistakes. I’d hate to tear the whole thing ago find nothing if there’s a simple fix . I’d like to check all the simple stuff first. Thanks for your reply.

 

Well all you'd have to tear down to check, is as far as the cam sprocket.

 

Do you have the plug in the block that's above the oil pump when engine is upright?

 

That won't cause "no oil pressure".

It separates pressurized unfiltered oil straight from the pump and rear main cap, from pressurized filtered oil returning from the filter going up to the rear cam journal where it gets distributed into the 3 front-rear passages along the cam tunnel. The pressure above it is lower than the pressure below it by only the couple of psi drop in the filter. If anything, lack of it will RAISE the oil pressure reading on a gauge, from not forcing the oil to pass through the filter. Leaving it out essentially turns the filter from an in-line component that all the oil must flow through, to a reservoir of sitting-still pressurized oil off to the side of the active flow path.



(not my spelling mistakes; I ganked it off the web somewhere already like that)

Which is of course, NOT to say "don't bother with it", or "leaving it out can't hurt", or "it doesn't matter", or ANY SUCH; please don't accuse me of saying that. All I'm saying is, leaving it out won't cause "no oil pressure". Other problems, notably accelerated wear and damage if the oil isn't kept scrupulously clean; but not "no oil pressure", at least not until the bearings get destroyed, which is pretty much inevitable.

 

I know that you said the parts are "all new"...but new parts today?....

I would check the front of block plugs first, too....BUT....I've had a lifter plunger fail and cause essentially no oil pressure, as all of the oil simply puked out into the valley, through that POS lifter.