[T3] Arc's sparks and missing the mark's

Jim Adney jadney at vwtype3.org
Tue Jun 4 05:40:38 PDT 2019

On 3 Jun 2019 at 20:48, Keith Park wrote:

> That what I thought, if its jumping at idle imagine whats going on at
> higher RPM. Im running .025, nothing higher, it's a solid core coil wire
> with the resistor At the cap end (Beru 1K 110degree removable end.)
> I cleaned the coil nose pretty well, there could be a microscopic trace,
> it seems to be jumping mainly in 2 spots.  I may try the NOS bosch coil I
> have as well.

First thing to do would be to push the boot up and out of the picture. That 
would allow you to see if the spark is coming up and over the end of the coil 
nose or diving thru it. If pushing the boot up stops the arcing, the boot itself 
was the problem. In that case, replacing the boot is simple.

After that, I'd try the different coil. If the arc doesn't happen with that, I'd 
suspect a track, crack, or puncture in this coil. I've had punctures in rotors, 
and there's nothing I could ever see, so the only option was replacement.  

One thing you could try, to save the coil, would be to pack the space inside 
the coil nose, all around the HV wire, with dielectric grease. That would 
probably have no effect if you've got a puncture, but it would probably stop a 
track, and maybe stop a crack.  

The Delta spark has a faster rise time than the standard Kettering system, 
which puts a bit more stress on our insulators, but the problem you're having 
doesn't happen to me with any of my Deltas, so there's something different 
about your system. I suspect the coil or boot.  

This IS a stock coil, isn't it? The Deltas don't work as well with fancy coils. I 
assume you know that.

Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA

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