Distributor-oil Pump Question

I have been fighting a poor fitment between my distributor and my oil pump since I rebuilt the engine. It seems to me the oil pump shaft is not quite centered under the distributor shaft, or maybe the dist. shaft is a bit off. Either way, its always been a PITA to get it the distributor to sit back down and seat all the way down into the pump (one time I pulled the pump gears and put the dist. in place and then put the pump gears back in). I also think the dist. shaft is just a bit too long - when it heats up the shaft is lengthening and pushing down on the oil pump and causes some extra oil leak out of the pump gasket.

But recently the amount of leaking oil increased a bit, and after some searching, I found oil is coming up through the distributor shaft (inside the shaft - not around the outside between the o-ring and timing cover) and the oil was pooled in the bottom of the dist. base. If I had points this oil would probably have killed my ignition a while ago, but with the Pertronix it hasn't been an issue (yet).

So, what is going on...how does oil come up through the distributor shaft? I am going to pull the oil pump and see how that looks - the pump gears may have 'machined' some clearance in to the pump housing.

Pic of the oil in the distributor - it looks like a shadow but its a pool of oil under the breaker plate:

 

Here is the oil pump bottom surface that the gears ride on. You can see a bit of sheen from the gear that is directly below the shaft. I cannot feel any ridge or surface wear but you can see the slight coloration. It's a bit asymmetrical. I thought it would be worse.


I think the temp expansion is pushing the distributor shaft up into the breaker/points area. I could add a spacer washer/shim at the base of the distributor against the timing cover. Or I could add a thicker gasket at the pump?

 

Sorry if I use the wrong terminology - I think you are saying the oil pump 'drive' shaft (that the distributor sits in) has a gap between it and the 'hole' in the surrounding housing of the pump and/or the timing cover that is allowing oil to go into the timing area. Guess that means I am getting good lubrication into the timing area - but somehow its working its way up the distributor shaft and past the bushing and press-fit connection with the bottom distributor plate. I will post a pic tonight, but I think there is some indication that the shaft has been pushed up and has damaged the pressed fit bushing-baseplate connection. Maybe this is allowing oil to come up and through into the breaker/cap area.

When I pulled the oil pump drive shaft out of the housing, it basically slid out an inch on its own, then stuck slightly - I had to very gently work it down and out of the housing turning the gear by hand and a slight tug. Combine that with the slightly asymmetrical wear pattern on the oil pump face place below the drive gear - i think there is a bit of a mis-alingment between the distributor and pump shafts. I think its leveraging the pump shaft to the side just a bit - and this may be opening up the drive shaft hole in the pump and timing housing allowing oil through. Not sure what is the best way to create better alignment - file open the slot in the pump drive shaft to allow for more slop with the distributor? I don't really have any way to tell if the pump drive shaft is perfectly straight and centered below the distributor.

The distributor, pump and timing cover are new from the rebuild (well the distributor is a cardone rebuilt unit from RA). I have to check the pump order form and box, but IIRC, the pump is the Melling high volume replacement pump. I think it came with 3 different springs for the valve, and I think I went with the middle spring. Wonder if I should put the softest spring in to reduce pressure a bit?

 

Its the usual 12psi or so at idle (800-850rpm - seems to not like any lower rpm with the new cam) and ramps up quickly with additional rpm.

I will check tonight and take pic of the of the pump shaft.

 

I run an open breather on the driver bank and the pcv valve to base of carb on the passenger bank. No smog or smog plumbing of any kind.

 

Agreed - what confuses me is with Pertronix, I am supposed to shim (spacer ring) the bottom gear to reduce end play so the magnetic pick-up and ring stay withing a certain spacing. I will have to check what that requirement is again, but it seems to limit how much expansion can occur. Pertronix has been run by a lot of people for a long time without issue, so it seems I may be doing something wrong - maybe I am reducing the endplay too much but I think I would have done it to the pertronix spec. I do currently have a shim/spacer ring above the dist. gear - but if I remove it, I think i will have too much endplay according to the pertronix specs (will have to check all these measurements this evening).

The last distributor I damaged had the felt ring in it. I didn't take this new cardone unit apart - so maybe it was left out.

One more question with regard to this...what is the best way to seal up the oil pump gaskets. I went with the provided paper-esque gaskets and installed them dry - no rtv or permatex or the like - didn't want to risk getting any of that into the oiling system and didn't want to add any additional thickness to the system. But they seem to leak a lot of oil. Considering there are two gaskets there - even if both leak only little, it adds up with two of them. These have leaked from the very start- make a complete oily mess of everything behind it (which is pretty much the entire engine and drivetrain).

 

Getting closer to that route - and would be better for the TBI I hope to install one day. But given my inability to even install this distributor i will probably never figure out an HEI. But honestly the pertronix has worked great for me - and it worked fine on my dist. before the rebuild.

Okay had a chance to look at this a bit more and disassemble the distributor. According to pertronix, it needs a gap that is maintained between 0.01-0.06" - which is plenty to allow the 0.015-0.02" endplay that Walt mentions. I had shimmed the distributor, but still had about 0.03" endplay on the bench - so that should have been fine. With the oil pump out, I cannot test this next theory, but I think I may have lost the endplay once the distributor was installed. In other words, I may have needed a spacer between the distributor and timing cover to raise it just a bit as there may not have been enough room down to the oil pump shaft. When the distributor was installed, it might have pushed the distributor shaft all the way up and used up all the end play and had no room to heat extend. I will definitely be more cognizant of that upon re-install. I remember I originally looked for a spacer of some sort, but never found one that would fit - even tried to make one.

Some other stuff to think about - I disassembled the distributor and found no felt disk to help minimize oil traveling up the shaft and into the cap/housing area. Anyone see any other issues?
It would normally look like this:


I believe the cam lobe plate should be able to move independently up and down on the shaft? The oil is coming up between the cam lobe bushing and shaft and coming out between the rotating advance plate mechanism.


The top of the lower plate has some gouging of some sort - no idea what made it, but it doesn't allow for the top mechanical advance plate to rotate smoothly on top of this- sometimes it feels like it would stick - maybe it doesn't matter at actual rpm.


Finally, here is the underside of the cam lobes - it should have some sort of felt oil seal - any idea what I can put in there as a suitable replacement?

 

I think my plan will be to smooth up the gouging on the plate the weights sit-on, try to find some sort of oil seal to put against the interior cam bushing to minimize oil flow. I might have one in my back-up distributor - have to disassemble that one to get to it. Will try to find some sort of spacer to put between the distributor and timing cover to allow for a bit more clearance between the two shafts. And just for fun and to try and keep some of the leaky oil under control - I will try putting some shellac on the gaskets.

 

ahhh yes....should have recognized that...thanks.

exactly...it's sticking a little bit...will try to smooth it out just a bit without loosening the staking...
Now off to find a felt or similar oil seal for the shaft and a spacer to raise it up a bit. Maybe I will go to work as well....

 

so where does the felt seal go? Think I remember...it goes in the housing bore base...