Distributor wobble

[lee_rob]

I have noticed that my distributor appears to be oscillating in its slot quite a bit, now when I overhauled the engine I used a new distributor drive gear from sports and vintage as the old one was damaged coupled to a new Bosch distributor. Do you think that the slot in the gear for the distributor may not be machined correctly and is causing the wobble??

[Ian Grace]

Lee,

The distributor should be free to rotate through the angular range of the manual advance/retard slot, so any wobble must be due to unwanted backlash somewhere. Can you feel this by playing with the rotor when the cap is off?

[Trevor Wilkinson]

I got over this problem by fitting "O" rings to the groove(s) in the distributor shaft housing to hold it central in the block.

[Ian Grace]

Not sure why there should be any play between the distributor body and the engine casting - it's not like one revolves inside the other? All the distributors I have ever fitted to Minors have been a nice sliding fit.

[Trevor Wilkinson]

I think that we are talking about a Bosch distributor that is slightly undersize.

[Ian Grace]

Interesting. If the Bosch replacement is loose in the engine casting, and enough to cause a visible wobble, then I'd be surprised it's a valid mod, unless it is sleeved?

I have heard that the Bosch mod transforms performance for the better. I'd be interested in other owners' Bosch experiences - good and bad.

[lee_rob]

It does make a massive difference to performance as you get a better range of advance throughout the rev range, I might try the O ring trick and see if that stops the play. I will say you have to be careful about setting up the ignition timing though as the Bosch has quite a lot of auto advance built in to it

[plj]

I presume the Bosch mod is an early 6volt Beetle distributor. Does anyone have the part no. plus source of supply to hand?

Regards,

Philip

[lee_rob]

I got mine through sports and vintage

[Simon]

On e-bay search for Bosch 009 distributor, the one without the vacuum advance. They have to be modified - see MMM website for details.

[lee_rob]

The ones from S&V are already modified ready to fit

[Ronald]

I assume everyone that has fitted this distributor has also added a seperate earth point, as, especially with the o rings you're effectively isolating the dizzy from the block, or even without them if the dizzy is loose it's less likely to get a good and constant earth, when MT's engine was rebuilt i made a little earth strap from the dizzy body to the block, wether it did much who knows, but i know for sure that i always have a decent earth!!

also, any idea how much they are from S&V.....??

[Trevor Wilkinson]

No I didn't add an extra earth,as the manual advance lever and linkage is still connected (but not operational) I am confident that this provides a more than adequate earth path.

My distributor was not supplied through S&V, it came from a VW tuning company in Scotland and was about £50.

[Toby]

I believe there are also lots of details of the mod at the pwmn site.

[Ian Grace]

From VMR Magazine M 125, written by Roger Lucke:

"I had been looking into fitting a distributor with an automatic advance and retard mechanism to my car. Neither Autojumbles nor eBay had produced anything suitable, when I heard that MG owners were fitting VW Bosch 009 distributors to their cars. This distributor is readily available, new, at a cost of £40 + vat complete. Spares for this are also cheap and readily available.

It needs a couple of small modifications before it can be used. Remove the driving dog from a Lucas distributor, noting its relationship with the rotor arm, and drill out the hole for the fixing pin to about 4.2mm. Remove the drive dog from the Bosch, by removing the spring ring and knocking out the drive pin. This pin is quite tight, and so a good parallel punch and hammer will be needed to remove it.

Assemble the Lucas drive dog to the Bosch, again ensuring that the relationship to the offset dog and the rotor arm is the same, and that you have about 0.5mm endplay. I don’t think you need to refit the spring ring, as the drive pin is quite tight, but if you want to, machine a groove in the Lucas drive dog to take this ring.
Remove the cap and rotor arm from the Bosch. Unscrew the condenser, and hold the whole lot securely with a binding of adhesive tape. Put the whole Bosch in a lathe, and machine back the shoulder by about 4 mm. The finish does not need to be particularly good, as only the distributor clamp fits here. This is an easy job, which takes about five minutes. The Bosch gives about 22° of advance. A Morris engine needs about 30° in total, and so the static timing needs to be set to about 8° BTDC retarded. The suppliers of the unit say that the best way to time it is with a strobe, as mechanical distributors always vary a bit.

For a source of Bosch 009 distributors, I can recommend John Maher Racing at http://www.johnmaherracing.co.uk/ Tel.01870 602519. For an in depth article on the Bosch 009, and engine timing in general, have a look at http://www.geocities.com/vwresource/dis ... _questions.