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

Keith Park topnotch at nycap.rr.com
Mon Jun 3 17:48:47 PDT 2019

That what I thought, if its jumping at idle imagine whats going on at higher
Im running .025, nothing higher, it's a solid core coil wire with the
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.

If anything, the voltage required at idle should be lower, because the
pressure inside the combustion chamber is lower. (Higher gas pressure makes
a better insulator.) You're setting the SP gaps normally, at .027 or .028,
aren't you? If you've gone to the larger gap that Delta says you can get
away with sometimes, that will cause problems, but the problems I've seen
have always been elsewhere.

Cap is new and looks good, carbon button is here, using a resistor rotor
(the rev limiting kind)

Yea, 3"  My goodness!  That seemed quite excessive to me. Don't remember
this problem on the stock T3 except when something was wrong like an open
wire or resistor and this all checks out, and of course the T4 system is
essentially the same.


Have you cleaned all the dirt off the nose of your coil, inside and out?
That's one thing that I do occasionally, because black crud seems to
accumulate there. It's also possible that you have a coil with a crack or
track there. I've never seen that, but it's possible, and it's also possible
for it to be so small that it's almost invisible.

Check the resistance of the HV coil wire. Some wiresets put a carbon core
resistor wire there, and those can develop a break in the core.

Check inside your cap to make sure the carbon center contact is still there.

You could try sliding the rubber boot up on the wire, to see if that helps,
as the problem/track might be in the boot or in the first inch of insulation
on the wire. Normally, any spark would have to run up the inside of the coil
nose and then down the outside. That makes for a nearly 3" track, which
seems way too long for a sound, intact insulator.

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

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