GM-HEI Modules

[Tony Bryant]

> From:          bamcknig at postoffice.syspac.com
> To:            diy_efi at efi332.eng.ohio-state.edu
> Date:          Tue, 17 Feb 1998 13:01:09 +0000
> Subject:       Re: GM-HEI Modules
> Priority:      normal
> Reply-to:      diy_efi at efi332.eng.ohio-state.edu

> Sandy
> 
> I have adapted HEI to VW.  The small pins(2) get the AC voltage from 
> the reluctor (maybe around 5v).  Check it with a scope as it is not a 
> sine wave.  My understanding is that it has to go negative to turn 
> off, so it may have an SCR(silicon controlled rectifier).  I don't 
> think you have to worry about the coil drawing too much current.
> The old HEI transformer(coil) put out one of the hotest sparks going.
> Their problem is that if there is no load on them(spark plug), the 
> voltage goes so hi that it arcs internally and ruins the coil.
> 

On a related topic, my '85 V12 Jag, uses a lucas ignition module, 
which is just a repackaged HEI system. This drives two standard 
looking coil wired in parallel firing NGK BP7EFS plugs @ .025" gap.

There is visible arcing showing through the ceramic, on all 12 plugs, 
just at the base of the plug. You can only see it at night.

It looks like it could be arcing between the ceramic and the hex, or
perhaps its just showing acting like a colourtune?

Is this normal for HEI systems or a sign that something is wrong? 

Thanks.