Been helping a friend out with a 350 SBC, mild performance bolt-ons, etc. - he just got it all put together.

Anyways, the distributor doesn't seem to seat all the way down on the intake like it should. The distributor gear is fully engaged, the oil pump rod fully engages, there's no damage to the gears or oil pump rod that's evident but the base of the distributor housing isn't squeezing down on the gasket at all....even when the hold down is fully tightened after the timing is set, it doesn't take much force to turn the distributor. It seems like it's maybe
1/32nd of an inch from seating on the intake.

The engine will start, runs and has good oil pressure. He's been cruising it around with no ill effects. I only noticed it when I was helping him set his timing. The distributor had a little "wobble" to it when I loosened the hold down clamp which is weird. I pulled his distributor out and everything looked fine. I even took out one of my old distributors to stab it in his engine, thinking that maybe he had a defect distributor somehow, and it "wobbled" too!!

Any ideas on what's causing this?? I've never ran into this before...

 

Don't take this negatively, but I don't understand how you can be so sure that the distributor is fully seated into the gearing and the oil pump shaft. You can't see inside, it's all about the feel and the fact that the distributor sits on the intake to know that it's seated. Man, I personally wouldn't have driven it with a "wobble". When I've reinstalled my distributor, I've gotten close, and thought it was there, but still required more fiddlin' to get it to completely seat.

Is the intake aftermarket? Was the oil pump changed out?

 

Not taking it negatively at all. I've installed plenty of distributors and know what a properly seated distributor is like. This one doesn't seem to seat properly which prompted me to post this in the first place.

I know that if it weren't properly engaged with both the cam and oil pump shaft, one or both things would not happen - 1. There would be no oil pressure or 2. the engine would not run at all. I looked closely at the dist. gear and it appears like it's wearing normally...

No matter how much you try to readjust the oil pump shaft to align with the distributor slot on the bottom, it didn't make a difference. It was fiddled with for over an hour. The intake is a Air Gap, and it's a stock pressure Milidon replacement oil pump for a SBC.

About the only things I can think of is that the cam gear is set too far back due to either a defect in the cam, or maybe the cam is thrusted too far back somehow? Or - Oil pump shaft is too long??

 

Could be tolerance stackup: the block and/or heads have been decked, the intake is too thin (its dist place is cut down too low), and the dist is shimmed up tight. Similarly, align-boring (moves the cap, and therefore the pump, up) could add to it although that's usually only a couple of .001"s at most.

It's also not impossible that there's something either about the block or the dist housing, that makes the dist hit something when it goes down some certain distance into the block.

First thing to do would be to figure out what's hitting, the dist shaft or the housing. If the shaft still has vertical play, then the housing is being obstructed; if the shaft has end play when lifter up but is tight when installed, it's the shaft, gear, oil pump, or OP drive rod.

 

what did you use for your intake gaskets if their too thin that will throw things off I have always used the rubber end cap gaskets on the front and back end of the block they about 1/4 inch thick and I have never had a problem with the dizzy with them cork and rtv always ends up in a goopy mess.

 

You said you tried a second distributor, I would think that would eliminate any possibility of a defect there... I had experience with Edelbrock intakes once, and it was my last. Maybe give their tech line a call and see if you can get the dimensions from the bottom of the intake to the distributor surface? I'd at the least put some kind of spacer between the distributor and the intake so it doesn't wobble any more if he's going to continue driving it, I just can't imagine that being good for anything.

 

Thanks for the replies....I've also thought about maybe the intake dist. mounting surface being off somehow....no china wall gaskets were used, just RTV. The intake manifold gaskets are just the standard run of the mill replacements AFAIK.

It's so close to seating properly that if I were to stack another gasket on top of the existing one, I think it would seat, but it should'nt have to be like that. I have done a couple internet searches and found that shimming is done in a few cases but I'd rather try and figure out the root cause of this really.

There was no decking or special maching done that we're aware of....just a standard hot tanking, bore, hone on all cylinders and replacement of cam bearings.

I guess the best thing I can do from here is try and figure out what's holding it back from seating this weekend. I have some machinist bluing...I guess I could put some on the dist. gear and on the bottom of the oil pump drive slot and hopefully see where the interference is...or at least if the gear is fully engaging maybe. I'll post back up if we find anything...

 

The "China wall" gaskets won't make any difference. They're real soft material regardless; the main intake gaskets, up against the heads, take up probably 95% of the clamping force, maybe more.

The odd thing is, there shouldn't be anything keeping it from going down all the way to the intake, except for the oil pump rod. You DO NOT want to tighten the dist against that, as all you will do, is load the end of the oil pump drive gear and the shim on top of the dist gear. If that's what's limiting the dist travel, it needs to be addressed, right away; either by un-shimming the shaft, or shimming up the body, or SOMETHING. Keep in mind, the shaft is pushed UP during normal operation, by the gear; so having extra play when the dist is out of the motor, if it goes mostly away when it's in, by way of sitting on top of the OP rod, won't matter. But there needs to be at least a small amount of end play in each joint along that train of parts (shaft - drive rod - pump).

 

Did anyone ever solve this? I've just come up against the same situation myself. Pulled the intake a few weeks ago, now just putting it back on. Same intake/distributor - but now dist won't seat by a mm or so, same little 'wobble' as the OP. With the dist clamp tight, can push the gasket around with a screwdriver (just barely).

It's not the shaft - still has vertical play. Something seems to be propping the dist housing up the tiniest bit, but its not the intake. Any ideas? Just double-gasket and leave it?

 

If the engine has hand any machine work, it can be off.

same goes for an intake, if allot of machine work was done to block and heads, it may not seat well either.

 

Probably not anything to do with the intake, heads or machine work.

The bottom couple of inches of the dist goes through the block, and completes the passage drilled all the way from front to rear of the block alongside of the cam tunnel that feeds the right bank lifters. That's what the 2 "ring" looking features around it are for. It's not impossible that something is stuck down in there somehow or that sort of thing, or that the block is incompletely machined or damaged in there.

 

I can’t believe I’m offering a solution. I just had the same exact problem. I removed the oil pump shaft and it seated perfectly. To fix problem I just made the notch deeper in the shaft where it goes into the bottom of distributor. Also had to grind the very end of the shaft equally because the shaft can only recess so far into distributor. I only removed an 1/8” from pump shaft. Don’t go crazy. Don’t thank me. I’m still learning all the time even at 47. God bless my brothers

 

Didn’t bother to learn this post is 14 years old

 

Is it just me, or is there really an unusually large number of new posters dredging up ancient threads in this site lately?

 

I've been seein' that on other tech forums I am on as well..... 15-20 year old threads dredged up looking for a solution..... Even though NONE of the original participants are still around.

 

And it also seems to me that this phenomenon always occurs at the first of the year for some odd reason.

 

yet here you are wasting your time criticizing it. WOW. This is the first thing that came up in Google last night when I toured in my problem. You’re being very petty son

 

Nothing petty about it. Just because it came up in a google search didn't mean you needed to resurrect it all these years later...

 

Not your son.

What makes you think a 14 year old thread will have any relevant information? Ever consider including a YEAR in your google search? Tends to bring up more relevant info......

 

It would be nice if these older threads were locked. It’s a hack of a repair to suggest.

 

^^^^THIS.

Using the correct parts, installed correctly, there should never be cause to have to "modify" the oil pump drive.

 

Old or indifferent, the thread still has some relevance for someone searching for a solution.
And I recently had to find a solution as the new oil pump (Melling Shark Tooth), melonized distributor gear (to go with the new billet cam) and original distributor (MSD) didn't play nice and the distributor wouldn't seat on the intake. Nothing else had changed.
I addressed the stack up of shims between the gear and housing and there wasn't enough in thickness to get the distributor to seat fully.
The solution was a Moroso distributor housing shim kit.

https://www.moroso.com/distributor-h...YR4ODIGVXybGts

Added the .060" (IIRC) and it all fit as it should.

 

If you are reviving an old thread to pose a question to someone who has not posted for years , I understand the distaste for that . but if you are adding relevant info to an old post I am all for it. These cars are very old and the problems are not new either. When we go looking for solutions old posts often pop up. If a new post adds to the resources on this site I am greatful.

 

Which is why I posted my findings.
Hope it helps somewhere.