Vertical movement in the distributor shaft causing no spark.

So the van had no spark and after a quick examination I find the the rotor isn’t moving, a quick play and I can push the shaft back down to engage it and the van fires - the distributor is clamped well and there’s no movement there, just the shaft.

Obviously, after this it doesn’t run for very long as the shaft pops back up and there’s no spark again.

Is this a new distributor job or if I remove the distributor can this be corrected?


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Have you loosened the clamp right off, and pushed the dissy body down as far as it will go? (With the drive lined up obviously)

 

^this, as a starting point. A stock dissy should sit right down on the crankcase.

 

Yes, the dizzy is right down and the clamp is nice and tight.

I did this first after reseating the shaft. There’s just loads of vertical movement, so much that it pops up and no longer spins.

The base of the shaft and as far as I could see and feel, the cam is fine too.


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Obvious question, but was it working ok before? Have you got the little spring in place between the driveshaft and the dissy?

Worth pulling the dissy out and seeing if the fibre spacer washer at the base of the shaft has disintegrated.

 

Yes, was working fine until a few days ago when it just wouldn’t start after I drove it outside my workshop and wanted to bring it back in a few hours later.


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Isnt it usually a lack of Vertical movement in the distributor shaft that causes no spark?

Asking for a friend.....

 

Check you havent tightened up the clamp so much so that the distributor rises up as it bows.
Also the chrome EMPI clamps tend to lift the distributor as the nut clamps it to the engine block.
Once it starts slipping, the drive dog burrs off on the Chinese drive dogs faster than OG.

 

Another set of nightmare thought are

• That the brass gear on the crankshaft has worn after being damaged by turning the engine without a distributor , the drive shaft rises up and chews the brass gear.(more likely scenario)

• The distributor drive shaft has worn and the gears are no longer meshing properly
  
• The shims under the drive shaft are missing and it has chewed its way down into the engine block.

These nightmares would largely have have root cause in an engine builder messing up.


If you use the blunt end of a pencil jammed in the circular hole in the drive shaft you can lift it up, or use a 25mm diameter neodymium disc magnet securely fixed to a stick to lift and inspect..


But first check the distributor has functional drive dog with square teeth, and about 1mm of shimming between the drive dog and the distributor nose.

 

Thanks for all the info, I’ll take a look tomorrow.

 

More likely the fibre washer has broken up.

 

Thanks for the help, I've removed the distributor and all looks ok.

Looks like mikedjames was right, as I've tightened the clamp it's pulled the distributor ever so slightly out causing the shaft to freely rotate - I've ensured that the distributor is engaged properly with the clamp tightened and she's now running well.

I'll get Autohaus Dolby to give it a good once over when she's in for a service.

 

I just bought half a distributor at Slough where the clamp was bowed, and somebody had heaved on the nut until it stripped the thread..Neither was necessary.

Hammered it flat and welded a new bolt on it..