As some have seen, I keep a log of my experiences with 123 here ...

 

https://zclub.net/community/index.php?threads/123-ignition-for-datsun-l6-on-my-l28.25467/

 

I wanted to share my latest experiences with you without duplicating that thread as I know quite a few on this forum also use / are considering 123.

 

In summary random missing and rough running that plagued me for months turned out to be a cap breaking down and doing a lively plasma ball impression under the bonnet. Short video below that explains what just happened ...

 

 

I will be experimenting with insulating the cap and clips with spray on insulation and clear nail polish respectively - I’m sure my wife would be delighted [emoji1787]

 

I am wondering if I should put the ballast resistor back in and reduce the coil voltage to avoid future antics - which does defeat the object of a flame thrower coil of course but I do wonder if the Z really does need 40kV!? [emoji848] If the spark is able to jump the 1.2mm gap then surely that’s sufficient.

 

What are your thoughts about ignition voltage?

The spark would have to pass through the cap material, or along the surface of the cap, to get from the electrodes to the outside.  A thin layer of nail polish is not likely to stop that.  Is there carbon tracking inside the cap?  Follow the path of the spark from the coil's center electrode, through the wire to the cap's center electrode, and then through the "button" inside and out the rotor to each spark plug electrode.  The lowest resistance path will be used by the electricity, of course.  It seems like bad cap material just based on the video.  There are conductive paths on the outside of the cap, probably on the inside too.

So Mr Z head - I did look for that but was unable to find anything really obvious. It seems like it’s going horizontally through the material from the bottom of the post inside the cap and arcing onto the clip.

 

What I did do was to cover the clips with heat-shrink and that took away the visible arcing you saw in the video. But engine still running less well than it should. So I suspect there is more arcing inside the cap or through material to a low resistance path somewhere.

 

When I was trouble shooting previously I found that when I unplugged no. 6 and no. 3 HT leads while the engine was running, there was a clicking sound from the dizzy side of the car - but no other leads made that happen. So I’m pretty sure the cap is defective on that side. New cap on order so let’s see what happens next.

 

 

 

Be careful with disconnecting your plug wires.  And sparks in general.  My experience has been that electronic ignition modules do not like stray electricity.  I fried a GM HEI module by leaving two wires disconnected by accident.

http://newautoaa.blogspot.com/p/secondary-circuit-of-ignition-system.html

Thank you sir - interesting reading for tomorrow a it’s past my bed time now ;)

But I agree - read this earlier today [emoji33]



It seems old tricks don’t suit new electronics!

Use a standard .. what is it.. 20-25 Kv  coil..  all that 123 ignition nonsense with 40+ Kv… gives you only one thing… trouble!!!…  just my 2 cents... 

Use a standard .. what is it.. 20-25 Kv  coil..  all that 123 ignition nonsense with 40+ Kv… gives you only one thing… trouble!!!…  just my 2 cents... 

Good advice chap! Thank you, will have to try it. [emoji106]

21 hours ago, AK260 said:

Good advice chap!

Yup!  That reminded me about Hugh Laurie and Stephen Fry! ( should there be someone who do not know them.. google them!)

Yup!  That reminded me about Hugh Laurie and Stephen Fry! ( should there be someone who do not know them.. google them!)

Jolly good then and bully for you old bean. My work here is done! ;)