Help! No Oil Pressure on Rebuilt 421 Engine
 

I have put a 1965 421 motor in my 63 Tempest. Motor was a running motor. Lower half of the engine was in good shape so just replaced the main and rod bearings. Top half of engine is rebuilt with #62 heads and a solid lifter cam. Has new stock oil pump and I stretched the spring about a ½ inch. I installed a new manual oil pressure gauge and had it visible during startup procedure. We fired this motor up but did not get any oil pressure registering on the gauge and within about 30 seconds we cut if off. Thinking the gauge might be faulty or that the oil pump needed to be primed, I pulled the distributor and tried spinning up the pump with a drill and homemade shaft. Still no oil pressure reading on the gauge and no resistance at all on the drill. I spun it both clockwise and counter clockwise. I even over filled the oil pan a little to get more volume. I am thinking I must have missed a gallery plug or something else is going on. Before I pull this motor out and disassemble it or pull the front cover, does anybody have any ideas as to why I have no oil pressure?

Detached pick-up?

Got to pin them.

There is one plug at the back of the engine down the distributor hole that is often forgotten about and is sometimes left out. You can feel the plug if you take the distributor out. There is a soft plug at the back of the block that you can take out to put it in, or you can put it in from the top of the engine with a little patience. Hopefully it is something simple.

Check the small galley plug inside next to the distributor gear.

or weld them

2 front galley plugs are missing.

Doesnt have Chevy lifters does it? With some solid cams, the base circle is too low to use the Chevy style lifters. Check your part numbers and call your supplier. The oiling groove is too far down and it bleeds all the pressure off. If the oil gallery plugs are in the back like they have mentioned on here, I would pull the timing cover and check the front gallery plugs. If they are in , then I would check the lifters. Also, even if the pickup fell off, if you overfill the engine about a quart, it should still build pressure.(if you get pressure doing that, then that is your problem. And it isnt usually a good idea to stretch the relief spring. It can build too much pressure when cold and blow filters off, gallery plugs out, etc.:2cents: Good luck and let us know what you find.

If there's really ZERO resistance to the drill, the pump is probably "bad". It happens, though not often with good pumps like Melling and Sealed Power. Perhaps the relief ball is "hung" from some debris.

Unlike a Chevy, if the pickup "falls out", the pump is still completely submerged in oil (unless a seriously "deep" pan).

Prior to pulling the "front" off, use the drill to spin the pump and look through the fuel pump "hole". If you see a TON of gushing oil, there it is! The gallery plugs. If it's not a torrential flood, that's probably NOT the problem. (a labor-saving tip...)

FWIW

Jim

Even if an oil galley plug or two were left out, you would still feel resistence on the drill while spinning the pump. You would also have prpessure with the pick up installed too.
something is wrong with the pump itself.

I had a 389 that had all three plugs left out, and it had some oil pressure. The lifters made a hell of a racket, and I knew something was wrong, but I still had a gauge reading of a few psi. I agree with Steve and Mr. P. The "quick look through the fuel pump opening" is an excellent idea.

No Oil Pressure on Rebuilt 421 Engine
 

Thank you all for your responses. I will perform the checks described. I don't feel any resistance at all on the drill. I also agree that with one or two galley plugs missing, I should still feel some kind of resistance. I'm wondering if the pump is bad also. I hate to have to remove this motor.

Mr. P-Body: Did you say look through the fuel pump hole or did you mean through the distributor hole itself? Just want to clarify.

Fuel pump. With a priming tool in place, you can't see into the distributor hole. With the distributor removed, you CAN actually SEE the plug (or lack of it...).

Jim

Is it possible when you took out spring to stretch it the ball fell out and you left it out?

All part of the deal... not much you can do with this one.

In the future, before you drop the motor in, it's worth it to spin the motor and check for oil pressure while it is still in the crate or on the stand. Much easier to sort that way.

FWIW, I've visited the engine build center that does the GM ZZ 572 engines (as well as the Circle Track engines and a few others) and they have a cold test 'reverse dyno' stand before the engine goes to hot test.

There is a big stainless tub, with a big electric motor and a u-joint drive that connects to the crank. With that engaged, and the plugs removed, the engine is primed with a big air tool then spun on the test stand's motor while they check oil pressure and cranking compression.

One engine, many years ago, had one cylinder with cranking compression in the 230 psi range (pass was 170-180). Everything was okay in teardown; but the Roush guys were there going nuts trying to figure out how to replicate the error for their cup engines, LOL.

Probably the relief ball is stuck off the seat.