alright i have been reading this write up on how to do the leading http://www.smbaker.com/rail/msd6a.html and it says to take everything out on the leading ignitor connect things together right. well would this work for the trailing also cause it also has a ignitor. just thought of this now and wonder if i am right.

 

yes , if you wanna run the MSD on the trailing you need to modify its coresponding ignitor, but run its MSD through the cap instead of directfire

 

Why is that and how?

 

run the MSD to the coil, the coil wire to cap, just like normal. from what ive read, running wastepark/directfire on the trailing plugs could unintentionally spark the chamber thats just starting its compression "stroke", which is bad news. hopefully someone will confirm/deny this from expierience, as i too will be adding another MSD for trailing ign. soon

 

cause if you run the MSD direct fire on the trailing it'll be fireing into the intake stroke with the wasted spark and it won't run... For example if your traling is at 10* BTDC like most of yours are then it will also fire 90* before that and be fireing at 100*BTDC.... it's not experiance,but math...

 

here is a quick diagram of how i wire the msd units with the ignitors

msd white wire ......... igniter negative side
msd small red wire......... switched 12 volts
msd orange wire.........coil +
msd small black wire...... coil -
msd big red wire........ battery+
msd big black wire...... chassis ground
you will need to give switched 12 volts (+) to the + side of the ignitor also
now the tach wire, yellow with green stripe that was attached to the coil (negative) now goes to the plug on the side of the msd trailing box
the job of the ignitor is to convert and amplify the signal from the distributor to fire the coils..
repeat steps twice if you installing 2 msd boxes



if you want to hook up the msd boxes without running the igniters follow these instructions



msd white wire ......... dont use
msd small red wire......... switched 12 volts
msd orange wire.........coil +
msd small black wire...... coil -
msd big red wire........ battery+
msd big black wire...... chassis ground
msd green wire..... directly to the magnetic pickup green wire bypassing the ignitor
msd purple wire..... directly to magnetic pickup red wire bypassing the ignior

now the tach wire, yellow with green stripe that was attached to the coil (negative) now goes to the plug on the side of the msd trailing box

repeat steps twice if you installing 2 msd boxes

 

ok so for the leading direct fire and use that write up and for the trailing use Roberts way to do it. alright i am set. forgot this but with the two boxes for the tach wire do i just connect them together and run them to the tack wire?