Dizzy - Mystery washer and nasty powder

[PrimeMvr]

I took apart my dizzy for cleaning/lube and when I set it on the workbench, half of a fiber washer fell out, but I don't know where it came from and the other half is nowhere to be found.

Did it come from the end by the gear? If so, between the steel washer and the shaft casing, or the gear? Some threads indicate yes, some say it's under the mech advance, some say both. None of the posts I've found were for a 930 (1987).

Also, the roll pin that holds the star wheel from turning on the shaft was crumbled to pieces. Anyone know where to get one of these as well as the gear pin?



My vacuum retard side is shot. All of this powder came from inside. Boost side is solid and will hold a steady 1 bar. Obviously I've had a bad vacuum leak I didn't know about! I don't really like the idea of vacuum retard anyway, so I'm just going to cap it at the TB.



Thanks,
Steve

[fletcher0780]

If you decide to replace your dizzy, I have a low mileage 87 930 one I'm parting with.

[PrimeMvr]

Fletcher, the internals look really good and there is no play in the bearings at all. Obviously there is a ton of axial play due to the missing shim. Do you have a pic of yours that might show where it's missing from? I can't find an exploded view of this particular dizzy. Thanks, Steve

[JFairman]

The gap under the gear you have the red square around is way too big and the washer was probably there.

Because the distributor drive gear is helical cut the timinng will be jumping forward and backward as the motor runs with that clearance.
There has to be some clearance there but I don't know the spec and thats way too much. The shaft and rotor may lift higher in the distributor and the rotor may touch the contacts in the cap.

If I had to guess I would say the clearance should be around .010 -.015 from bosch distributors I've worked on. If you can't get the right part new you can go to you pull it junk yards and pull bosch distributors from seventies and early eightees BMW's and other old German cars that still had them. Alot of little bosch distributor parts like that washer are the same size and interchangable.
A banjo fitting copper sealing ring that fits on the shaft nicely there with a little axial clearance or end float play would probably be better than nothing but maybe I shouldn't suggest trying that.

[HFR_Racer]

Steve:

The black fiber washer does go where you've shown the RED box on your photo. I just refurbished my distributor for my 87 930. I purchased a BOSCH Distributor Shaft Kit Shim Kit w/Seal Ring 059-998-211 from TexasAirCooled.com for $11. This kit comes with the fiber washer and the stainless shims for setting your end play. You need the igntion advance/retard canister. If yours hold vacuum then its good. You need this to retrard your timing under boost or maybe a big $$$BOOM$$$ will happen There are several threads on Pelican discussing retarding your ignition under boost. New ones are available from Napa

I set my end play at 0.030" since I felt that 0.015" was too tight. The aluminum housing of the distributor shaft should be allowed to expand/contract due to heating/cooling. I also cleaned up my mechanical advance and added a new shim to hold the rotor (mechanical advance) off of the aluminum distributor housing. My stainless shim was almost gone and the rotor was starting to touch the alumimum housing

You also need the OEM drive gear pin since it's a special part. I considered using a double roll pin until I found the following.... The hole in the distributor shaft is smaller than the holes in the drive gear. This pin must be crimped tightly to ensure that the gear doesn't move. I made a die that I used in a hydraulic press to mushroom the ends of the pin. This pin is pretty tough material.

If your distributor shaft is tight in the housing then you likely don't need the bronze housing bushings. Mine did not nee these and I've got 97k miles on the clock. I lubed the shaft with engine oil prior to re-assembly.

Anything else?

[PrimeMvr]

Excellent info HFR, thanks. Do you know what the spec is for the gap between the bottom of the housing and the top of the gear? Is one fiber washer, one shim and .03 play "perfect" to line the gears up? I love working on this car, but there is so much conflicting and incomplete information out there because everyone's is different from 25 years of mods.

Did yours have a fiber washer under the advance mechanism also? I've read a number of conflicting posts. Replaying in my mind, I really think the half washer fell out of the inside and there wasn't one on the gear end (ugh, probably disintegrated inside the case).

What's the theory behind this type of washer? They seem mighty brittle.

I understand the detonation danger of too much advance on boost. The boost side of the can is operating fine. It held 1 bar for several minutes with no leakage. It's the vacuum side that is toast. The lever seems to move a little roughly though. Once I get it timed I'll apply some positive pressure and see what happens to the advance. I've been reading up on using the MSD boost retard and that sounds like a more reliable solution, but I'm not ready to pull the trigger on that until I see the results of the dizzy clean up and retiming.

[HFR_Racer]

My distributor has several shims + one-(1) black fiber washer between the drive gear and the distributor housing. The multiple shims are used to set the distributor shaft end play (approx. 0.030"). The faces of the driven and drive gear are pretty wide and the contact surface is fairly narrow so the gears lining up isn't really an issue. I did not have a fiber washer underneath the advance mechanism when I took mine apart. I've added one now and I plan to keep a sharp eye on it to see how long it lives there

It is likely that the other half of your fiber washer fell down in your engine case during years of wear. This fiber washer is oil lubricated and I believe mine to be original so they seem pretty robust.

Info on the vacuum.boost canister: The vacuum advance side of the canister has very limited travel. The distributor uses mechanical advance so there really is not need for vacuum advance.. This is why the canister arm travel is limiter during vacuum ( advance ) and allowed to travel during retard (boost). You should study this canister further once you get your distributor apart for cleaning. You will see that the canister only has one diaphragm inside and that the vacuum portion is mechanically limited in its travel

[PrimeMvr]

I've decided to delete it and go the MSD route. I've ordered a 6530, tach adapter (just in case), 8222 coil and a 3 bar MAP sensor. Now off to research plug choice and find a resistor-less rotor...

Serious case of "while I'm in there"!

Thanks for the tip on the shim kit, I ordered one of those as well.

[mooney265]

keep us posted on the change-out... I'm interested in doing this some day...