Problem with my Mark III diagnosed!

marshg246 said:

There are several types of camshaft bushings. Only the MK3-style (06.5428) has an actual thrust surface against the inside of the camshaft sprocket. The others only have the thin wall of the bushing protruding through the crankcase. I've seen those worn flush with the crankcase. Generally, the camshaft can only move so far towards the timing side but can move towards the drive side significantly depending on the bushing and bushing wear. This really didn't matter with points but can with electronic ignitions.

I don't know much about Boyer or Pazon, but Tri-Spark has rotors available to resolve this issue. Fortunately, I've only ever heard about it - it has never happened to me with Tri-Spark but then if the bushing is worn, I replace with the MK3-style. Of course, that requires splitting the cases.

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SteveA said:

Does Boyer make a range or rotors?

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The yaki said:

I fitted a pazon system on my mk3 as I read that it would spark at a lower voltage than the fitted boyer while using the electric start . Seemed a good idea. No spark ! Didn't seem as if the pickup pins on the rotor were in far enough to reach the coils on the stator plate. Was informed by pazon they had to produce a rotor with longer pins to address this problem. Not free ? Slight improvement but according to the measurements requd still 3 to4 mm short ! Got back in touch and was told to make a spacer to bring the rotor out farther. Tapered fit !! Had to make up carefully made shims using a variety of bits of an old set of feeler gauges so I could get it right . Works now but not impressed to say the least !! Roy.

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The yaki said:

I have no idea but the previously fitted boyer worked out of the tin. No spacers. Same camshaft ! Pazon suggested that I had an aftermarket camshaft that was wrongly machined ? As I said, the boyer worked !

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marshg246 said:

If you mean 3-4mm short, IMHO, that's huge. I tried to find the gap recommended by Pazon but could not - have they told what it should be?

I would turn the engine where one valve is just opening and then backoff that rocker adjuster to release the pressure on the cam. Then you can see how far in and out the cam moves. On a MK3, it shouldn't be much - not sure how much but if a lot then maybe it will lead you somewhere.

BTW, Tri-Spark requires 1.4-2.6mm between the rotor and back of the Tri-Spark stator. Sounds like you would be WAY, WAY too far in to run Tri-Spark and I've never personally come across a Commando that won't work with Tri-Spark.

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