connecting MSD 6AL to one-wire '87 930 distributor?
 

I'm changing engines and lost the paperwork for my MSD box.

Does anyone have instructions for connecting MSD 6AL to one-wire '87 930 distributor?

Send me a direct e-mail and I'll shoot you the instructions.

Hi Steve,

I'm at Chris@Laughary.com

http://forums.pelicanparts.com/uploa...1301016920.jpg
http://forums.pelicanparts.com/uploa...1301016941.jpg

Oh boy, I seem to only have one wire into my 3.3 disty.

I'll post a pic soon.

Thanks much!

You have two, its a coaxial cable: a center conductor surrounded by a braided shield.

If you have the distributor coax wire polarity wrong at the MSD CD box the timing will be advanced quite a bit because the trigger signal from the distributor is a square wave and from what I've read the MSD is triggered at the end of the square wave when the squared off slope falls.
If you've seen a picture of the distributor's square wave from an oscilloscope or computer monitor it's easier to see that.

Both polarities will run the motor but the wrong polarity will usually make it idle higher because the timing is being advanced and that will very likely hurt the motor if you get into boost with it like that.

I thought it was AC voltage coming out of the dist. If thats the case what would it matter what wire went to what wire. Also isn`t the coaxial wire there just for RF interference.

I don't know about the 930, but the SC dizzy output is voltage ramp up (or down depending on polarity) followed by a rapid voltage reversal and another ramp down. The trigger is meant to be on the rapid voltage reversal. If you hook up the wires backward the MSD will trigger on the ramp instead of the reversal. This will be about 30 degrees too soon and is very ambiguous because it's not a steep ramp.

-Andy