Last fall I had issues with the oil system priming after sitting any length of time. I pulled the NEW Milodon high volume pump apart, and found it to have .004 end clearance. I hand sanded the housing down till I have .0017 end clearance, and now the pump pulls a prime right away. Milodons spec for max end clearance is .004. Why they would send them out the door already at max end clearance is beyond me. But I am now somewhat happy. Next problem, I have a big leak at the rear main seal. I put phosphorescent dye in the oil to help locate the leak, and after running the oil pump with an electric drill for over a minute, the only leakage is coming out of the seal area, so a new hi performance Felpro tan colored seal is on order.

I'm surprised the leak at the seal shows up just priming the motor. The only oil that gets to that area would be dripping down from the lifter area or coming out the rear main bearing. With no crankcase pressure to blow the oil out the chance of that leaking would be minimal. So with a static leak it would almost seem like you forgot to install the seal altogether.

One of my friends ran into rear main seal problems last year. Had 2 new ones leak. He said the black fel pro are made in china now? I decided to use the tan colored Fluoroelastomer in mine this year to be safe.

Doesn't leak. (thank god)

Seems odd to me as well...I'd bet Cam plug before a static rear main leak

I got the opposite; I have one that locks up when bolted on...Like no clearance at all. Luckily, I have a surface grinder at work.

A surface grinder is the perfect machine to do the job!

I found my notes from 2008:
I disassembled, measured, and checked out my new oil pump for the motor. It is a Mopar Performance high volume pump, P4286590. It appears to be a Melling high volume part since cast into the body is "63 HV". Here are the details:

Cover flatness: Checked with precision parallel bar, none (spec <0.0015)
Rotor to housing face (flat) clearance: 0.002 (spec <0.004)
Outer rotor to housing bore: 0.008 (spec <0.014)
Rotor tip clearance: about 0.0035 (spec <0.010)
Inner rotor thickness (height) 1.1873 (spec ?, std is 0.943 min)
Outer rotor thickness (height) 1.1873
Outer rotor diameter: 2.473 (spec >2.469)
Spring free length: 2.245 (spec 2.25)
Spring diameter: 0.473

Win and Stanton, i fired the motor, and had a puddle about three by six inch in short order. I put in a new seal, and tried again, this time with a vacuum leak plugged that had kept the vacuum at zero. This time it only leaked about half as much, but still a small puddle. So i bought some dye and a UV light and ran the pump with a drill only to see if it was something other than a seal leak. After about two minutes of 80 psi oil pressure, no leak. Overnight some oil with dye in it showed up below the seal, but only a couple drops of oil formed on the motor plate below the seal. So that leads me to believe i have a seal leak only.

Personally I like the factory seal retainer housing. I've started opening up the holes in the housing by one drill size. This allows the housing to center on the seal itself. Offsetting the seals halves in the block and cap helps with alignment as well. I use Ultra Grey by itself to fill the side cavities, no seals. The rear main seal in my motor has been in there for years. Even reused after freshen ups. If it aint broke, don't change it. It uses the red seal.
Doug

Is that their black billet one? Mine does the same thing don't know when but it's going to happen.

All I have ever used was factory retainers. Split halves 1/4 inch or so. Slight dab of ultra grey on ends and thin coating on outsides of seal halves being careful not to get any on seal lip. Seal outer with Ultra grey. Never had a leak.

Its the Milodon high volume, black aluminum body pump. Now, after reducing the end clearance, it pulls a prime very quickly.

I ordered a hi performance Felpro seal, tan in color. It is listed as for race motors with vacuum pumps. So i will do the best i can to clean all surfaces, use ultra black silicone (oil resistant), guide pins to install, and rhere is wiggle room around the bolts so the retainer should self center.

Get the seal retainer flush with the back of the block.

RESPECTFULLY, I'm not sure what's being conveyed by DVW and Moparacer is understood. when you install the preferred 'tan' seal in both the block and the retainer there are ways to see the lips are 'line-to-line'. Also, putting a dab of rtv on the seals where they are cut is a good idea. Be conservative so it won't squeeze onto the crank surface. Let it cure a few days too.

Ok, i spotted the mention of ultra grey, GASKET MAKER. That and the use of stock retainers. Hardcoreb, not sure what else you feel i am missing hear. I have room for the retainer to "self center", but with the motor in the car, not sure i can gaurantee that i will fill the side cavitys properly. I am getting a bore scope to see if i can identify rhe leak area better.
The retainer i am using sealed fine on the first assembly, dyno and some runs.
Feel free to comment on what you think i am missing.