[SEL] Ignitor question

[Rob Skinner]

On Jun 29, 2008, at 5:08 PM, Michael Tucker wrote:
> I have a couple of igniter questions. I know that with spark plugs, a
> spark plug may have a reasonable spark outside of the cylinder but  
> fail
> to spark inside the cylinder under compression. Is that the case  
> with an
> igniter? I'm getting irregular spark out of the igniter on my 1907 4  
> hp
> IHC Famous. Although there are times when it doesn't spark at all and
> I'm not really sure which wiggle or other assorted voodoo seems to get
> it to spark, whne it sparks it seems to spark well when it's grounded
> outside of the cylinder. However, when it's installed on the engine I
> don't seem to be getting spark (plenty of gas, plenty of compression  
> and
> timed correctly). So, back to my question, are igniters like spark  
> plugs
> in that they may not fire correctly under compression?
>
> That's the situation and question for educational purposes but I guess
> that the bigger and more important question is who have y'all used  
> that
> rebuilds igniters who will be able to do it BEFORE Portland?

Heya Mike,
I'm assuming that you've already checked that the trip is operating  
satisfactorily and the moving parts are moving freely.  I'm also  
assuming you've got it all clean and the contact faces are parallel  
and smooth.

In my completely unqualified, unestimated and unconsidered opinion,  
most ignitors are poorly designed.  I don't even know what an  
International ignitor looks like.  BUT... most ignitors rely on the  
current traveling through the ignitor body and the movable contact.   
Got that?  It's an electrical connection that isn't solid and is  
contaminated by oil and goop.  It makes my head hurt just thinking  
about it.

Maybe the design is good when the ignitor is new, but the more it  
wears, the worse the electrical connection becomes. you can test this  
by taking a jumper wire with alligator clips and jumping between the  
movable contact and a good ground.  If this alleviates your problem,  
you can drill the end of the shaft, tap it, and make up a permanent  
jumper by winding some old-style wire around a pencil.  It can look so  
original that no one will know it's not original.

Improvement of that connection is the main thing you get out of an  
ignitor rebuild.  You'll get new insulation, as well, but that's  
nothing that you can't do yourself in ten minutes.

Rob