distributor gear bottom to block clearance?

[Jim Comet]

I have an MSD 8594 distributor and put a steel gear on it for my forthcoming solid roller cam. I installed it to MSD's specs of 3.050 from the upper seat to the bottom of the gear. When I installed the distributor in a dummy block it makes light contact with the lower pilot and I cannot get a feeler gauge under it. I am assuming I need to reinstall it so I have clearance under the gear and there is no contact with the block. I should have checked before drilling the new hole. Now I will be adding a 3rd hole in the shaft. Is there a clearance spec that is recommended between the gear and block? Jim

[blykins]

Did you take the play out of the shaft when you measured?

[Jim Comet]

I pushed the shaft up to take the play out as I measured. I am using a digital slide caliper for what it is worth. Jim

[blykins]

Stab the distributor in, clamp it down, and pick up on the rotor to see if you have play there.  If so, and your install spec is good, then let her eat. 

FWIW, I always shoot for the low side of the spec when installing gears.  Also, if you end up having to move the gear and drilling another hole, I would suggest buying another shaft from MSD and swapping it out. 

[scott foxwell]

I had to put a bronze gear on my MSD. The one hole in the bronze gear was nbo where hear the original. I don;t like having two holes in my dist. shaft so I measured carefully and put one hole in the bronze hear exactly where the hole in the original gear was. I measured from the face of the gear that would rest on the block. Once I did that, I put the gear on the shaft and left it a little long, put the distributor in the block and let the gear find it's "home". I did not push down on the shaft to take up the end play. I previously measured my end play at .023", so I moved the gear up the shaft half that distance. What was really nice was that the hole I drilled in the gear lined up perfectly with the hole in the shaft. All I had to do was finish drilling though the hole and through the other side of the gear. Took a little while to get all the measurements, but it came out perfect and was right on spec with MSD's numbers. What I don't get is how far apart MSD's numbers are, and Ford's numbers. I don't see how they can be different and still work.

[blykins]

They are not apart from each other.

One is taken with the end play removed, and the other is taken with end play.  The MSD spec requires you to push the gear it towards the rotor. Ford want you to pull the gear out away from the rotor.

[scott foxwell]

This is a good final check, from Ford:

With the aluminum distributor housing fully seated against
the block, verify that the distributor gear can be lifted off the
support in the block at least .005". Next pull the distributor
gear down against the support in the block and hold it there.
Pull up on the aluminum distributor housing and verify that you
can lift it up at least .005" while holding the gear against the
support in the block. This procedure will confirm that the gear
is not being forced down against the support and not being
held up off the support in the block.

[Jim Comet]

Good info Guys. I will check tonight. Thanks. Jim

[Jim Comet]

Well it looks like I am going to have to redo it. When clamped down tight it does not bind or drag but I cannot get a .005 feeler gauge under it. I marked the bottom with a grease pencil installed and spun it and it smeared the grease but did not wipe it away. I hate to take the chance of wiping out a custom cam/engine over a $300 distributor. I will call MSD and ask about a replacement shaft or just having them rebuild it. Jim

[C6AE]

Note that with some distributors, pulling up and down on the rotor will only verify end play in the mechanical advance mechanism. I have taken apart engines and distributors that were pretty well fried from lack of clearance at the thrust washer above the gear. I like to check them with the advance mechanism removed.

[scott foxwell]

Note that with some distributors, pulling up and down on the rotor will only verify end play in the mechanical advance mechanism. I have taken apart engines and distributors that were pretty well fried from lack of clearance at the thrust washer above the gear. I like to check them with the advance mechanism removed.

Good point. That's why they tell you to check everything at the gear.

[Falcon67]

Also, if you end up having to move the gear and drilling another hole, I would suggest buying another shaft from MSD and swapping it out.

I have a damaged 351C MSD distributor here, missing "teeth" off the reluctor. When I asked MSD about buying a replacement part (shaft with reluctor) they would not sell me one.  They insisted I send in the whole unit for expensive rework.  If you have the stick to get a replacement shaft for an MSD 8580 unit, I'd like to know about it because I have $250 of junk here that could be put into use.

[blykins]

Been a few months, but I have regularly bought replacement parts in the past. 

[Jim Comet]

Pretty sure MSD show a reluctor on their website.

[Yellow Truck]

Not exactly on this topic, but I had the strangest interaction with MSD last year when my new distributor went bad twice. I installed it and it ran for about 2 minutes and quit, so I sent it back for repair or replacement.

I was told that they confirmed it had failed, but then had to put a new shaft and gear in because the shaft was bent, when I called next to ask why it hadn't been returned, they told me it was because they had removed the gear and would not re-drill the shaft, and then they told me they couldn't return it because they were out of shafts and had no idea when they would EVER get any new ones, and they told me they couldn't replace it with a new distributor because they didn't have any of those either.

After I had a bit of a fit on the phone the guy said it didn't make any sense to him either and he'd get back to me. He then told me that everything I had been told (including in writing) was wrong, and there was nothing wrong with the distributor and they were returning it. I got it back, put it in the truck and it ran for 10 minutes and quit. I returned it for a refund and bought one from Faron.

My point is that MSD has some real internal issues and it seems really hard to get an intelligent response from them.

[Jim Comet]

I called MSD this morning and they had the parts in stock (shaft, bearing, seal and shims). just under 70 bucks for all and said I should have it next Tuesday. Jim

[Falcon67]

Pretty sure MSD show a reluctor on their website.

On the 8580 it is welded to the shaft.  Not separately replaceable.  Have to have the entire shaft.

>My point is that MSD has some real internal issues and it seems really hard to get an intelligent response from them.

They are part of the Holley group and having been part of mergers and acquisitions in the past, that's not unusual - but still not acceptable.  Maybe I ran into the same deal - will have to try again.