rally pac and msd box

Hi, David...

I don't know didley about the MSD box (I'm sure others will chime in about it), but if you're new to Rally Pacs, you need to remember that since the Rally Pac tach is wired in series with the coil, if it fails, your car dies. This is NOT an uncommon occurance for a 40+ year old electrical part. Maybe the MSD box changes this dreaded tach wiring. Someone on here will know...

I've had this happen to me, as I'm sure others on here have as well. When you hook the Rally Pac tach up, it's good to route the tach wires for easy access under the ignition switch. This way, if it fails, you can just reach under the dash and jump the tach out of the circuit, and you are back on your way in no time.

BTW, I'm in Stamford, CT

Gerry

The Ford/Mustang Rally Pac used the distributor's points grounding to generate a signal indicating RPM. Electronic distributors, Pertronix included, do not have points so original Rally Pacs will not work. There are supposed to be aftermarket Rally Pacs that will work on electronic type setups so that's your choice.

Jim

I don't think that the comment about Pertronix is correct.

My 67 Shelby's tach is hooked up exactly like an original

Rally Pac (have in fact tested my Rally Pac in the Shelby)

with a Pertronix and it works fine. An original Rally Pac

is hooked up in series (like stated above) and is connected

through the resistor wire from the positive (+) side of the coil.

/Bo

Yup, you're correct. It's the type of electronic tach that requires a wire to the negative of the distributor to function that I'm thinking of, the type that is sitting in a box in my garage cause it don't work on my Pertronix.

Jim

I have the same wiring as the rally pac on my tach & am using the MSD dist. & box. I had to add an MSD tach adaptor to made the tach recognize the ignition signal. Works great.

Z. Ray

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Now when you wired it did you only run the single wire from the box to the tach or did you still run it off the coil. I'm a little confused on where the wires go when wiring the rally pac. I have seen people ask this on here before and most of the time they get reffered to the wiring diagram from a place like Mustangs Unlimited. I bought this diagram and it tells me nothing. I need to know where the wires go not just plugged into under the dash, due to my harness being spliced all over. Please keep the comments coming you guys have been great on everything I have ever asked on here.

Duke

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everything you need is on the MSD website.

http://www.msdignition.com/1download.htm

you will need to buy a MSD 8920 tach adaptor.

here are wiring instructions:

http://www.msdignition.com/pdf/8920_frm22049.pdf

there are 2 illustrations.

are you using a MSD ready to run dist (can be used w/o or with MSD box) or a MSD billet dist, or some other dist.? The answer will affect how you wire in the tach adaptor.

Z. Ray

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Edited by - zrayrichter on 05/07/2008 16:34:11

Edited by - zrayrichter on 05/07/2008 16:35:35

Hi Duke,

I have the 66 Shop Manual in front of me now and the

Rally Pac wiring can be seen in section 15 page 16.

If you have an original 66 Tach you just hook it up between the

wire that is coming from the coil (pink resistor wire) and the end going to the ignition switch. To be precise: Black wire from Tach (female connector) shall be connected to pink resistor wire (male connector) and red wire (male connector) from Tach shall be connected to red-green stripe (female connector) going to switch. If you connect the pink and red-green wire together, i.e. bypass the Tach the car shall start without any problems.

The light hook up is also shown.

If you have a repo tach it is most likely to be connected differently.

Good luck!

Please keep me informed how it's going

/Bo

checked on my car and made revisions to post.

The hot wire from the ign switch goes to :

the red tach wire and to the red wire from the MSD box.

White wire from the MSD box goes to the points.

Orange wire from the MSD box goes to the positive side of the coil.

Black wire from the MSD box goes to the neg. side of the coil.

White tach output wire from the MSD box goes to the tach adaptor.

the red wire from the MSD 8920 tach adaptor goes to the tach black wire

Violet wire from the tach adaptor not used

Heavy Red & Black wires from the MSD box go directly to the battery.

Z. Ray

Edited by - zrayrichter on 05/08/2008 09:38:06