After finally getting everything together and getting it on the run stand, I'm not able to get oil pressure from just spinning it over with the starter. I have included two videos, one spinning it over with just the starter and one using a drill on the pump. It basically shows it takes quite bit of speed and time to get things started. I am using a Milodon pan, pickup, pump and a Meiling pump cover-all new stuff. The videos are after three days of sitting. The line from the pan to pump has a curve to it, where it is higher than the pump for several inches. I didn't take the time to measure the pump, but after this I guess that is my next step.

I looked through several threads and this does seem to be a common issue, it just seemed there was no single bullet-line routing, oil filter drainback, pump drainback, air leak, etc. I didn't plug the internal pickup, as the Milodon pump is solid where that hole is thus it shouldn't allow any air flow.

https://youtu.be/Os7D8fHTSQg?feature=shared
https://youtu.be/epGIRQvukyM?feature=shared

The oil pressure gauge is sitting in the middle of instrument panel, you can zoom in on it.

What happens when you spin the drill atfull speed from the start? I guess i'd remove the line at the pump itself after setting. See if it's full of oil. if it's empty drain back is happening. Mine has no loop. Has no issues. Even when the pump gears got chewed up from a broken valve spring. It still primed and had good pressure.
Doug

I installed a simple brass swing check valve near the pan on mine. It was unnerving how long it would take to make oil pressure without it.

Just a thought………
If the anti-drain back valve in the filter leaked a little, would it exacerbate the losing prime situation?

Even when I hit the drill full tilt it will take 4-5 seconds for it start picking up oil.

Anyone have a link or picture they are using for a check valve?

I dont have this problem with my melling pump, but i did with my Milodon oil pump and was told by Best Machine to either switch out the O ring on the end of the snout/shaft for a larger one that will fit or smear a small dab of rtv around the O ring. If the O ring leaks it can suck air. Dont use too much RTV, if it gets into the pump it will snap your oil pump shaft. Just a thought.

I've had several different Milidon external oil systems loose the prime after sitting a short while, 8 hours upto 5 days, others that never lost the prime after I started making my own oil pump to block gaskets that fit around the oil hole to the block and snug against the boss that the oil pump drive fits into.
As far as the O ring on the boss, snout, it shouldn't slide up into the block easily, even with oil or grease on it, it should have to be work and have to be twisted around a little while pushing it into the block

I think I remember reading in the instructions for the pump that said you have to use the included larger o-ring and not a standard one.

Would the motor being tilted forward make a difference? I have my back legs on the run stand a little high right now so the engine actually tilts forward a bit, which in mind should help prevent draining the line.

Cab-do you have any pictures of your homemade gaskets?
What material are you using to make them?

I don’t mind making gaskets, I actually made some .015 intake gaskets for this motor-the Fel-pro material is like $6.00 on Amazon.

At this point I am going to pull the line off the pump to see if I have oil in the line. How much oil should be there? Is it a go-no go situation, where if there is any oil there, then it has to be an air leak situation with the pump?

I have a brand new meiling high volume pump sitting on the shelf, so I would be tempted to bolt it on and give it a try. My only issue there is that the Milodon pump cover (top port) interferes with my Schumaker mounts, which is why I bought the Milodon pump and shaft to start with, plus I hate the idea of having bought $600 of oil pump only to not have it work ($400 pump/$200 shaft).

I have no, repeat NO, experience with remote pickups. But the way you have the suction hose with the loop at the top, is there any way you could route the hose with the loop at the bottom? When I did piping design I always tried to eliminate a high point on a pump suction as it takes a lot of flow to eliminate the air pocket at the top. If this is a stupid comment just ignore it.

Sorry no pics. Plumb this in down near the pan and it will solve your problems. Just be sure to install it in the right direction. At least it worked for me.

https://www.amazon.com/Eastman-Brass-Swing-Check-20425LF/dp/B00GZ3H5JA/ref=sr_1_3?keywords=swing%2Bcheck%2Bvalve&qid=1696080923&sr=8-3&th=1

What Milodon pump number is that? Most have this note:
NOTE: This pump does not use stock Chrysler O-ring around gear set. Special supplied O-ring must be used, also available in system rebuild kit #21590.
I don't know if that is the problem.

I would try a different filter and, if that doesn't help, install a check valve in the suction line.

https://www.summitracing.com/parts/hse-4152-12-1

Quick update:

Pulled the line and there was very very little run out. I pulled the pump and it was extremely easy to pull out of the block. It looks like I used the stock o-ring on the snout, so I used a larger o-ring and made a full gasket to go between the block and pump. I primed it and will try turning it over with the starter tomorrow. If no go, then I will put a Baldwin filter on and it try again. I will likely go ahead and get the check valve.

Thanks for all the help.

No pictures, I bought a sheet of fiber type gasket material years ago, not paper type, that is around .030 thick.
I would use a stock type OEM oil pump to block gasket to trace that on the gasket material and trace the hole to the block bolt holes, cut it out and punch the bolt holes out with a hole punch and then install it with 4 3/8 short bolts with large fender flat washers and then cut out the oil pump snout hole carefully

I fought this issue for quite a while. I did all of the above mentioned tips and tricks. Nothing fixed it. I even plugged the old oil pickup, filled it with RTV and made a custom gasket. Didnt help. I ended up replacing the pickup line, and all the fittings including the one into the pan.

That finally solved the problem. Still dont know if it was a bad fitting, a leaky hose, or something with the pickup????? All i know is now itll sit for days and have oil pressure right away.

If you do that make sure you mount it horizontal with the hinge for the flap up top.

I have always had this problem with my single line setup. Both static and swinging pickups. Had the line above the pump, below it. Run a 51515R wix filter with a drainback. No difference.

I have an accumulator so I never worried about dry starts but when I change oil I have to pull the distributor and spin it at high speed and it still takes a bit to pick the oil up.

I need to go through it next oil change and check some things mentioned here. Because priming it every oil change is a PITA.

Put the drill to it this afternoon and ran it pretty slow, I had pressure within 2-3 seconds running it slow. I went ahead and traded out the filter to a Baldwin, primed it again and will let it sit another day and try again.

What is the trick to getting the intermediate shaft in place? Seems like everytime to go install it, I spend 20 minutes slowing turning the oil pump shaft then dropping in the intermediate shaft only to find I am one tooth off one way or the other. It is like the intermediate shaft doesn’t engage the pump until the shaft is already engaged with the cam thus if the hex isn’t lined up it will not fall the rest of the way in.

Drop the pump drive in. Then turn it backwards so it hops up on the cam teeth. Then back in the forward direction. go back and forth like this. It'll skip a few teeth then drop in. If it's still in the wrong position keep at it until it drops where you want it.
Doug

Get a longer priming rod and use it to turn the pump shaft to were you want it