Distributor failure identified

[Andy Bennett]

Further to my earlier post about my lack of spark, I thought I would round off the story as I don't like not knowing what went wrong as it usually means it will happen again.

Having got everything running with my old bosch distributor, I went back to the Accuspark unit and nothing, no spark, back to Bosch and all was good. At least I now knew I was looking at a distributor issue.

As a reminder this is an Accuspark unit bought in Sept 2017 and installed early 2018, it has covered fewer than 500 miles.

I have investigated and found that one of the weights is free. The result is that there is no advance and retard mechanism working, the spindle just freely slops backwards and forwards and rotates through the advance and retard allowance. This tied in with my first problems of a near misfire as I tried to start the engine.

I have attached 3 photographs.
The first shows the weights sitting incorrectly and not closing up under the springs.
   


The second shows the one weight working correctly and centralised having been pulled back in. I have annotated it with a note to the pivot point where the peg is secure).
   

The third is annotated to point out the pin (as on the previous picture) and the plate with the hole which should be located on the pin but is floating free allowing the weight to move around and the spindle to rotate freely.
     

The pin is not sheared. It is just proud of the surface and you can juggle the plate back to catch on the pin and then all appears to work fine on the spring return mechanism, and then it slips off again. 

It might be that it has been in this precarious position since new and has just slipped off a pin that was simply too short. Or the pin may be a push fit into the weight and may have slipped down. I don’t want to take it further apart having spotted the problem.

It appears to need a new pin inserted and either secured properly or just a new pin of the correct length used so that the plate cannot slip off it.

I have contacted Accuspark and will let you know what happens.

Andy

[Ruairidh Dunford]

I have seen one of the brass spring location lugs broken off these.

What has caused the lack of spark though?

[Ruairidh Dunford]

Found the picture - this still ran but not as smoothly as it had.

Was replaced immediately, as you’d expect.


   

[Andy Bennett]

Thanks R
Although I say no spark, I couldn't see one and it wouldn't start. I didn't spend too long playing with it.
Having said that, if you look back at my first post, it was misfiring when trying to start and ultimately ran for a short time but very badly, so it was consistent with very poor and erratic timing.
Interesting to see your failure on a different point. Given other comments in previous posts there does seem to be a frailty running through the design in a number of areas both mechanical and electrical.
Andy

[Ruairidh Dunford]

The Bosch replacement had no spark either initially, is that correct?

The Accuspark unit is mass produced and the very low price reflects this, some issues are inevitable amongst such production, as you will be aware. Yours and the one pictured above are the only mechanical failures I am aware of - so far.

Most of the electronic issues I have experienced with these units can be drawn down to set up, the unit will fry if any connections are loose or poor.

What Ω protection does your current coil provide? Anything below 1.5 will eventually destroy the trigger units, I have found.

If the trigger has run well for 500 miles I would suggest that something else has upset it, rather than faulty workmanship this ties with the Bosch unit not sparking early on either. I would suggest looking carefully for a wiring fault somewhere in the loom or switches, if you intend fitting the replacement Accuspark unit, otherwise you will be facing similar issues not too far down the line again.

My advice comes from fitting over 50 units now, hope you find it helpful.

[Andy Bennett]

Hi Ruairidh.

Appreciate further thoughts but re the Bosch operation, not quite, what I noted on my original post was that:

'I then took the Accuspark distributor off and replaced with the Bosch (again was fine when removed). Would not start, but when I played around with a lead on a head stud I saw a very faint spark.'

When I then tidied up the points, and HT leads (different from those on the Accuspark) then it fired up. So I always had a spark with the Bosch, just not enough to fire her up.

Having said that, I have today been going through all the leads etc and remaking/soldering crimped joints and making up new HT leads with soldered ends to try to remove any potential wiring problems, so agree with you that I need to have all bases covered.

Om the mechanical frailty there was also a report of a rotating shaft from a 'crimp' coming loose and of course the (once removed) problem of the meshing gears. Again, having said that, the performance difference from the unit was clear to me and I hope that I can get a repaired unit back in.

Interesting question re coil resistance. I will measure that tomorrow, especially if it is that critical.
Thanks as always
Andy

[Ruairidh Dunford]

Glad you are moving forward Andy, all good news in the long run.

I am confident it will all work out, it usually does.

[Andy Bennett]

Just to bring this to conclusion.
I have now received a bright new free replacement distributor from Accuspark. Full marks for replacing it outside of the warranty period. Took it apart and it has full pins right through the weight plates.

Now my dilemma is that in the meantime I got the car running nicely on its Bosch distributor and it is definitely too cold to be changing over again right now.

Perhaps my electronic distributor will become my backup to my Bosch, although that seems a little bottom about face...

Andy B