Distributor trouble

I recently rebuilt my 5.0 (87 engine) and my boyfriend and I cannot get this distributor to install all the way.....

We've got over 10 hours trying to get this to install...we tried every trick in the book:
1. Turn the hex oil pump shaft slightly and tried re-inserting the dizzy like a million times
2. Tried the above and tried turning the crank....when 180 degress backwards and forwards and it doesn't help
3. Tried putting some grease to stablize the oil pump shaft also no luck
4. Tried using new (summit) and old distributor (stock motorcraft...both same install height
5. Tried slightly beveling the bottom of the old distributor

Car rebuild info that may be helpful:
> The deck is stock/unmodified
> new melling high volume oil pump
> same block and we are also trying the old dizzy too...

Here's my picture of the lowest intall we get on the beveled old dizzy, I also illustrated what I beleive is happening...the angle of the shaft is being maxed out so it cannot go on all the way???

....we've taken measurements of depths of the oil priming tool and we can see a hex shape being formed in the distributor shaft from the lube we've used...so I know it's going in the dizzy and we're convinced it is inside the dizzy but again the angle won't let it go in farther.....so I think it is engaging the shaft!

Is this installed enough to tighten down the hold down?
Could the oil pump shaft be floating slightly higher in the pump causing this issue?
What are we supposed to be doing at this point?






Here's a pic BEFORE the rebuild and where the same dizzy sat before:





Please help me get my new baby running this weekend!!! This is the last part to be installed after a 7 month rebuild.....

After some additional checking we're convinced the distributor is bottoming out on the retaining clip....we even went to the store and pulled the same HV melling pump from stock and compared the retaining clip install height to the old one; I also recall the retaining clips being in different positions but didn't think it was something that had to be modified.

So....we're probably going to shave 1/4 or so off the dizzy shaft after we verify the exact measurement.

the old shaft discoloration seems to imply it sits at least an inch or so inside, so removing 1/4 shouldn't matter too much for functionality.

looks like I've found a few people have had this issue with the high volume melling pumps...the retaining ring being installed too high and the dizzy is bottoming out on it.

I've revised my concept drawing:

I'm going to take my dizzy to work with me tomorrow and have the machine shop trim it down, this way it's more precise

I'll follow up and confirm how it all works out

shaved .27" off the dizzy worked
We're sure we're still getting approx .90" engagement

dizzy sits flush

starting the engine tomorrow after this 7 month overhaul!

My oil pump shaft was installed properly, meaning upside down with the engine out of the car at the time, the shaft was put in the block pilot hole, then the pump bolted down with the shaft seated in the pump. The pump primes perfectly So; I installed it correct where...the retaining clip prevents it from comming out after the pump was bolted down. What I failed to do was check and modify the clip install height.

The issue is, the melling high volume pump installed the retaining clip way to far up on the shaft...this is confirmed by pulling a unit at the store, our own measurements, and someone else's experience with the same exact pump

....being totally new to engine building or even installing a pump or dizzy before; I didn't think the different install height would have hit the dizzy (at least looking from the bottom side of the engine I didn't realize it would have been a concern). I didn't test fit the dizzy...and should have. I left it last for install so we could prime the pump before start up.

We talked to a Rick at RNH Performance of PA who had a block on the stand at the time and he took measurements for us. We then measured on my stang where the oil pump priming tool was bottoming out at...and sure enough it was hitting the clip! He told us that the clip should be installed at a 5.7" depth and the dizzy will normally engage the shaft 1.28" when fully seated.

Based on this info; we took measurements with a copper rod and it bottomed out at 5.4"
We also double checked this using the oil priming tool. So; my clip is sitting .30" higher than where it should be. We checked the dizzy and to ensure I wouldn't drag on the clip decided to go with 0.27", I think .25" would have been enough but with a chance of hitting the clip. Based on the 1.28" normal engagement, our engagement should be around 1.01" or so.

I shaved the dizzy because I felt the clip is too tight pressed in the shaft, and I didn't want to tap on it and risk it falling too far down or falling off, many other guys would have done this without an issue- but I wanted to take a safer route (eliminating the chance of clip failure).

Here's my final concept drawing for what we learned

She runs!!!!!!

gotstang.com - 4nomore Overhaul: Update #36: It's ALIVE! by Nicoleb3x3