Distributor shaft end-play - did I correct it properly/safely?

Matt Kennedy · Mar 31, 2006

When installing a new Ford Motorsport distributor gear in my stock ’89 Ford 302 distributor last night I noticed the shaft end-play far exceeded the specs that were on the Ford Motorport gear install instructions. They indicate that the shaft end play must be between .024 to .035. Mine was over .050. The difficulty was the instructions simply stated that if the end-play was not in spec “modify the collar if necessary” and nothing more.

As I pondered how to approach this I kept coming back to how they were instructing me to install the new gear. Basically press the gear onto the shaft to within spec and drill a hole through the gear (it comes without a hole) and the shaft so that the new hole is 90 degrees away from the original hole through the original gear & shaft.

I decided at that point that I could just follow this same approach with the collar to correct the end play. I drove the roll pin out of the collar. I pressed the collar up the shaft until the end play was within spec and then drilled a new hole through the collar at 90 degrees to the original hole and drove the roll pin back in.

My main concern and the reason for posting this was to see if anyone with more experience than I might know whether my approach to correcting the end play as described above is safe/sound/correct.

Lastly of course after correcting the shaft end play I then pressed on the new gear to within spec and then as recommended in the Ford instructions I drilled a .125 hole through the new gear and the shaft at 90 degrees to the original hole and drove the roll pin back in.

I’ve triple checked and everything is now within spec. Would really like to hear from anyone with an in-depth understanding of such things as to whether my approach to correcting end-play was appropriate/safe/sound/correct…. Not to make a big deal out of such a small thing but I also realize the potential distributor problems can have…

Thanks a million.
-Matt

Bongo Bob · Mar 31, 2006

Do you have the gear to match the distributor.I believe there are 2 different shaft diameters. A possibility for the gear tightening up on the shaft my be due to burrs on the inside of the gear from the drilling process, Bob

1686 · Mar 31, 2006

Matt,

I've never run into that issue, but your remedy sounds appropriate. The reason for limiting the end play, is that the gear will ride up higher on the cam because it is helical, and cause the teeth to wear at a faster rate because they aren't engaged deeply enough. If I'm understanding what you did correctly, it seems that you determined the excess play to be in the part of the shaft that isn't controlled by the gear position. By taking up the slack with the collar, you were then able to have the gear at a lower point relative to the thrust surface in the block so that the shaft wouldn't be able to move up and down more than the .030", or so - right?

Brian

p.s. I haven't gotten a chance to reply to your email, but I'll try to get to it later today...

Matt Kennedy · Mar 31, 2006

Bob, Thanks but I think you misunderstood. My concern with how I corrected the end play in my distributor really has nothing to do with the gear install other than I decided to check and correct the end play before replacing the gear as recommended by Ford.

Brian, thanks. These are two completely separate specs your distributor must meet according to Ford. They are independent of one another. The first is the end play which can be felt if you hold the distributor cap body in one hand and attempt to slide the shaft up and down with the other hand. My shaft slid up and down over .050 but should have been limited to between .024 and .035. The way I resolved this is the part I am questioning.

Once you have the end play within spec you push the shaft downward and hold all the end play at the bottom and then measure the distance between the bottom machined surface of the gear up to the surface of the distributor that sits on the block when it is installed. That dimension should be between 4.031 and 4.038. Has to be within .007!

It is the the way I resolved the end play that I want to be sure is OK. In doing some searching on the internet today I do see that some parts suppliers offer shims that appear as though you can slip them in between the collar and the distributor housing to correct end play. Although I am still fairly confident in the approach I took to correcting my end play (as outlined above) it may be non-standard so I was hoping for some reassurance that it should be OK.

Note to anyone using high-mileage distributors in your builds: ...be sure to check and correct the end play in your distributor (or replace it) if it is out of spec. This can result in poor timing and possibly issues with the wear of your distributor gear and cam gear.

Here is a link to the instruction sheet I was following - Steps 1 and 2 address end play http://www.fordracingparts.com/download/instructionsheets/FordInstShtM-12390-A.pdf

[ March 31, 2006, 03:06 PM: Message edited by: Matt Kennedy ]

Matt Kennedy · Mar 31, 2006

OK, I *may* have found the answer. I just got off the phone with Ford Motorsport Tech line. The guy on the tech line said he would have corrected the end play using the exact same procedure. Of course I am always just a bit leary of the advice I get on free tech lines but I am feeling a little better. Just wish this was in a text book somewhere - “modify the collar if necessary” is just a tad on the vague side for me still.

mustangII460 · Mar 31, 2006

If you get time this is kinda interesting. http://www.cobralads.com/butcher63.html

Distributor shaft end-play - did I correct it properly/safely?

Our Vendors

Top Contributors this Month

Recommended Communities