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MSD question

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janjon:
So I bought an MSD Pro-Billet distributor with the intent of running it with a Blaster 2 coil and no box. The installation instructions show how to hook it up to a 6 or 7 AL but not without a control box. This is a two-wire setup. The box the distributor came in states that most MSD distributors require a box. It also mentions "ready-to-run" distributors that have three wires. Anybody have any idea whether the two-wire setup can work, and how?
I will call tech support tomorrow, but I'm posting this on the off chance somebody might tell me what I want to hear tonight, in which case we might yet piss off the neighbors this evening.
Thanks for any comments,
John

janjon:
Well xxxx!
Tech support says no way will it work, gotta run thru a control box. The distributor I need to wire it like I want to costs $50 more than the one I bought. I do have a 6AL that I got from somewhere, swap meet, maybe, but I have no idea if it works. If not, $200 or so for a new one. So my question becomes, do I get significant performance increase from the multi-spark aspect of the control box? Or other spark characteristics?

Spud Miller:

 Hi John,

 Most distributor setups need at least 3 wires...

 - Trigger wire: the distributor usually has some sort of trigger device in it and this is the signal out to your box. You don't HAVE to use this if you have some other means of triggering the ignition (crank trigger pickup, etc.). This device is usually a reluctor/pickup, LED....

 - +12V: The trigger device inside generally needs 12V input to create the output trigger signal.

 - Ground: Even though the distributor probably is grounded internally, everything always has a real ground wire as part of the harness.

 The multi-spark thing is a farce for a race car. The MSD boxes only have multiple sparks below 3500 RPM. Usually, they make three sparks per firing below 3000, then they drop back to only two until 3500. By 3600 RPM, they are ONE spark per firing.

 For a street car running down the road, this is great. But it doesn't do anything for a race car at all.

 The most UNDESIRABLE spark characteristic is that as RPM increases, it'll need another AMP per 1000 RPM. As supply voltage and current to the box drops (unless you're running a charging system), your spark will diminish. More spark cycles means it needs more energy and after starting your car, the batteries take a dip and spark suffers.

janjon:
Thank you, Spud, for the reply. I read somewhere that the primary benefit of MSD would be to possibly facilitate the transition from idle or thereabouts to WFO, if the "atmospheric conditions" in the cylinder didn't allow the fire to get lit the first spark, the subsequent ones had a chance to do it. At some point there simply isn't enough time for second chances.

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