I've known the gear on the main shaft inside those mag/coil conversions to slide completely out of mesh. Had to rebuild Eddie Williams' one in the paddock at Loton once (just to let him then soundly beat me!)
Given that it's a bevel gear if it's moving on the shaft it would be altering the timing, messing up your performance and then sliding back into place again.

Charles

I have heard about this happening as well Charles.

Are you talking about the gear inside the body of the conversion?

The gear is solid on the shaft of the distributor but there is some play (2-3 thou) at the cam end of the shaft - which I was surprised at - what symptoms did Eddie experience when his failed please?

Yes. It was the gear on the main shaft through the conversion. The gear is keyed to the shaft - it's a bevel gear that mates with the distributor gear so any axial movement will alter timing. In Eddie's case the gear slid completely out of mesh and he stopped. We fixed it by making a spacer out of petrol hose and lock wiring it in position.
It struck me as odd that the design allowed this mode of failure as a positive location isn't hard to incorporate. It may be hard to mimic the loading causing a possible gear movement on the bench.

C

Thank you Charles.

Can anyone who has suffered the failure of a Bosch distributor shaft/baseplate/bush describe the symptoms please?

Is 2-3 thou play normal in units as new as this, the appear much more sensitive to timing than Lucas models?

I have recently been having fun and games with Bosch distributors. In my case the problem has been the points. On some they are not flat faced but male/female which I believe is to prevent a pip forming. When I replace this type of points with a flat set from AccuSpark everything is hunky dory. The symptoms were idling okay and misfiring above about 2000rpm.
If ordering Bosch distributors or parts for them my experience is that the AccuSpark products are of superior quality. I have heard of people using the coil conversions and having problems with the Bosch distributor which are of inferior quality in some cases.

I find a magneto works well for me...

Thanks Malcolm.

Do you know hat kind of problems have they had - were symptoms similar to the ones I have described and what was the cure?

I have to agree, I fitted a fully rebuilt BLIC to own car 8 years ago and have never looked back.

In this instance I understand the conversion was fitted because the magneto had become very unreliable and several rebuilds had not improved the situation so I have some sympathy with the decision to change.

Thank you for all the suggestions, very helpful and appreciated.

My plan is to fit another conversion that I have and know to work perfectly - if this cures the problem then I know something is amiss with the new unit and will investigate it further.

If it does not cure it then I will substitute the carb with one that I know to work and go on from there, I will report back what I find for those interested.

Thanks for all the pointers here and also to those who emailed and phoned, what a collectively great resource you all are!

Lots of fake Bosch parts out there!

At the risk of upsetting your supplier try asking them to return it to Bosch or take it to an authorised service centre for testing

Location: Near the birthplace of Morgan cars (which isn't Malvern)

HI,

I recently replaced my Dk4 with a bosch 009 and TBH have had loads of issues with it ever since. I restricted the advance as per different threads but have found TBH that the points gap seems stupidly sensitive which is driving me nuts. I have had pretty similar symptoms, lumpy/misfiring idle, refusal to rev beyond about 3k revs and lots of popping back. Almost came to the point of asking if anyone had a spar DK4 to do a test with!

David

Interesting.

The first 009 I bought, many years ago via Mick Kirkland was ace on my car. It ended up with dad via musical engines and is now on my daughters RP. What is odd in that it doesnt was to rev in 3rd. It just hits a flat spot. Which isnt there in 2nd at similar revs.

Its replacemen to me, which I assume came with a rebuilt engine from Vince Leek to father was on my RL (with the same engine) and went like a rocket. As did the special engine once I fitted it to that. I fitted a new one from Willie on my RL and it still goes like a rocket.

Ive never bothered with fitting the limiter to any of them.

But now youve got me thinking about the RP and why it hits this flat spot in 3rd. I had thought it to be a jet issue. Hmm

Sorry Mr Dunford Sir. No help to you

Something that hasn't been mentioned, and is possibly irrelevant, is that the original genuine Bosh distributors as used in VW beetles had the cam lobe modified to give slightly different timing on No.3 cylinder (I think it was No.3!) This was to overcome a over heating problem with that cylinder due to it's location on the air cooled engine. I can't say that this seemed noticeable when fitted to a Seven. Bosh stopped making this distributor several years ago, any supplied in the last few years would be repro and may not have this mod. The quality of the repro types has always been suspect!

Location: Moonraker country

Update:

I have fitted my own coil conversion to the car and it appears to be running fine now, fingers crossed.

I have found the following issues with the unit that was fitted:-

Rotor arm - the black circle is not carbon as I originally thought, it is a hole that goes throughout he brass and into the plastic below.



Cap - the carbon brush has been pushed up into the cap and disintegrated, the cap does not fit down on the body of the distributor. Either the spindle or the rotor arm is too tall or the cap too small.



Spindle - after approx. 1000 miles of use the spindle is worn with 4-5 thou of play at the top evident when pushed as shown below:






Thanks again for all the help and suggestions.

Must say fitted the latest version of coil conversion from Willie McKenzie runs well on my Twelve.

Location: The Centre of The Universe

The original Bosch rotor arms had a single piece of brass from the centre to the outside. The nice AA man removed the one on my daughters Beetle when she broke down near Bristol and fitted one like Ruairidh's photo, that lasted as far as Stoke. When another AA man came to her rescue he couldn't fix it and she was relayed home and it was my job the fix it. In the space between the two bits of brass is a suppressor which is well known to fail, there was a warning about it in the PWA7 club mag a couple of months before this incident in 2003, so I knew to dig the suppressor out and solder a piece of brass in. Then I had to find the original fault-a leaking air manifold joint.