i have a 440 in my 74 cuda i am installing a msd6al ing box will i need the ecu and ballast resistor and is there anything else i can get rid of iwant the least amount of stuff in my engine compartment that i can get by with

the msd needs the full 12 volts so no ballast resistor, you could just run a jumper aross it or run the wire behind it. the msd eliminates the factory ignition module too. thats the only things you can take out of there.

You can ditch the ecu but I think you need to keep your ballast resistor, not sure though. The installation diagram for the MSD shows the red wire going to your old coil + wire. The coil + wire gets its power directly from the ballast. The ballast is there to step down voltage to the coil, because full voltage is too much and will burn it out. I know some aftermarket coils don't need ballast resistors at all, but some do, so you probably still have to run the correct ballast resistor for your specific coil. Or does the MSD unit somehow 'know' how much voltage your stock coil gets? I can see if you run an aftermarket msd coil, but for a stocker?

Anyone else, am I wrong or am I right? I've had a msd 6al sitting in a box in my garage for a while that I never did get around to using yet...

I ran an MSD 6AL for years W/ a balast and never had a problem.

Then I kept hearing everyone say I didn't need one and should take it out. So I did.

Guess what. Burned up a coil the same weekend.

Put a ballast back in W/ a new coil and not an issue since.

thanks for the help

I'd leave it all there and keep your old ECM in the trunk...you never know when it will go out. Same w/ ECM's and ballast I keep extra of them too.

The ballast resistor limits current through the coil so it does not burn up. The MSD box wants no resistor so it can generate maxium current flow in for max current out for the multi spark sequence.

It does not make sense to me to add a MSD without adding a HP coil that can live without a ballast resistor.

Exactly, if your using a stock coil i believe you need the Ballast or it will overheat. Put a Blaster 2 coil (12 volt) and get rid of the Ballast.

Guys, honestly the number of times this is debated!!

It makes no difference (to the MSD) whether you leave the ballast resistor in or not. Yes originally it is there to step down voltage after cranking, but the MSD supplies the coil +ve via the orange wire and earths through the black wire to the coil -ve. The small red wire just needs an ignition-switched source, it doesn't feed the coil at all. MSD often show that switched source as the original coil +ve feed wire - it's just a handy switched source, that's all. The MSD unit can live with that being 12V or less (i.e. via the ballast resistor). It does not affect the output, the coil etc.