Dual ign system question

[Roger Heflin]

On Thu, 17 Feb 2000, Garfield Willis wrote:

> On Thu, 17 Feb 2000 09:54:31 -0600 (CST) Roger Heflin
> <rah at horizon.hit.net> wrote:
> 
> >On my car right now I have two fully functional ignition systems.
> >Both have coils and plug wires, on one system is setup to generate
> >spark at one time.   Is it possible to have one wire running to a plug
> >and two different systems feeding that wire with spark?   Would one
> >coil sparking backfeed the other in a bad manner and possibly damage
> >one system or both systems?
> >
> >One system is a DIS system and the other is a basically a classic
> >coil/distributor type setup.  I would expect both systems to fire at
> >roughly the same time, but I could adjust the dis system to fire
> >several degrees after the optimal fireing position that would be taken
> >by the coil/distrubitor setup.
> 
> WHOA, I just noticed this. You're talking about joining a dizzy IGN with
> a DIS/wastefire system!!?? I wasn't following the thread closely enough,
> I see. If your DIS system is a wastefire system, I take back what I said
> about the MSD coil-joiners being suitable. I don't know of a way to
> combine these two types of systems, because the dizzy IGN wants to fire
> the plugs all in the same polarity, and the DIS wants to fire the plugs
> in pairs of opposite polarity. There exist coil-joiners for waste-fire
> systems, if you want to combine two of those IGN systems in a redundant
> pair, as well as the MSD joiners, if you want to join two dizzy-based
> systems (one dizzy w/two pickups & coils), but I don't know of any way
> to mix up the two (DIS with dizzy) when firing the same set of plugs.
> 
> Shoulda stayed out of something I wasn't paying close attention to.
> Argh. Sorry for the mislead.

So on a dis system on of the two towers is -50kv (ref to engine
ground) and the other is +50kv?   I could see there being a bit of an
issue with that, esp if both systems fired a the same time.   So
anything wired on one of those -plugs would always fire a -50kv pulse,
so depending on what the stock coil is firing, 4 cylinders firings
would always have the wrong polarity.

Just in thinking about this, I am finding out alot about how each ign
system really works.

It sounds like the easiest way would be a plug with two completely
separate electrodes/insulators/connectors, which would be not dooable
in the given space.   

It is starting to sound like to switch I deactivate the power to one
ign system  and switch plug wires.

			Roger

----------------------------------------------------------------------------
To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes)
in the body of a message (not the subject) to majordomo at lists.diy-efi.org