Switched power question.

[Shakin66]

I am having some issues on the MSD Digital 7 box I have installed and need some help. The box has a wire for switched power and I connected it to the stud on the back of the key switch but that does not show 12volts while you hold the key on "start" so the box shuts off and I have no spark....Any ideas as to a good spot to wire it in that is off with the key out but on while on while in the on & run positions?
Thanks in advance

 

[Tim65GT]

The stud on the back of the Ign sw is for Accessories. You should pick up switched power for your box from the red/green coil (C) wire where it comes out of the Ign sw before going to the pink resistor wire.

 

[Shakin66]

Thanks! I had run it on full power just for testing reasons. I have found the wire and now it shuts off with the key.

 

[brianj5600]

Mine is hooked to the pink wire. It has no trouble turning on an MSD. The pink wire has battery voltage at low current loads.

 

[Shakin66]

Just an update. The car did great on the way to work this am and I am very happy with the MSD box & coil. I cant believe the differents in the power and it starts up easier as the box retards the timing under 500RPM to help it start. Thanks for the help yesterday!

 

[brianj5600]

Where did you set the timing with 0 retard? I keep a program for setting the distributer that has only start retard on run retard and no boost retard. Did you set it up for vacuum advance?

 

[Shakin66]

I have not had a chance to play with the programing as of yet. As an old school mechanic the program seems a bit intimadating. I am getting the current gains strickly from the switch from a vacuum dist. to this mechanical advance. I cant wait to dial up the advance some on my way home. If you have any tips please let me know as Satuday & Sunday I will be working on the programing.

 

[brianj5600]

I locked the timing in the distributor and set it for 42* btdc. This is with no retard in the box. Always hook up to a computer to verify 0 retard when setting the distributor. I pull 20* start retard and leave it out until 1000rpm's when it starts feeing back in and have all timing back in by 2500. This is all on the run retard chart.

On the boost retard chart I start retarding at 10psia which is around 10 inches of vacuum. At 14psia or 0 vacuum it has 8* retard which puts it at 34* btdc. From there I pull about 1.1* per pound and end up at 23* at 24psia or 10psi. It is a little confusing thinking in absolute pressure. If you turn on the key motor off and look at the monitor box it will tell you your local pressure. There will also be a red line on the run and boost retard charts telling rpm and absolute pressure.

 

[65fastbackresto]

Question about how I wired my MSD box.

I had the same problem Shakin66 had, where I couldn`t run the wire off the MSD box off the back of the ignition. So I ran wires to the battery and MSD box with a toggle switch under the dash, is that ok?

 

[brianj5600]

As long as you remember to turn it off. Have you tried the pink wire?

 

[65fastbackresto]

I have to turn it off to kill the motor.

Could call it an anti theft device of a sort, unless you know the switch is under the dash, you aint starting this car.

I actaully planned on leaving it this way, I have 43 yr old wiring.....and I`d rather just leave it alone.