Here I go again trying to avoid mistakes before I make them! Can anyone help me out as far as how they wired in a MSD 6 to their ignition system? I am about to install mine but I am terrified of burning up my new tic-tock-tach and I want to make sure I can get it working with the MSD. There are a number of different wiring diagrams outlining the installation which one has anyone followed, with success for a 68 with a factory tach?

http://www.msdignition.com/pdf/6%20series/6series.pdf


Thanks

What type of distributor are you using?

I have a MSD pro-billet 85551 that I was planning to use.

Are you converting from points?

When I converted my car from Points:

Heavy Red Wire from the MSD box on the junction block under the fender near the battery (constant 12 volts).
Heavy Black Wire to the Frame or Body (I have my box on the firewall and used the fender to body bolt).
Thin Red Wire to Ignition Switch wire.
Thin Orange Wire to Coil Positive.
Thin Black Wire to Coil Negative.
Harness from MSD Box (Green/Purple Wire) to MSD Distributor Harness.

If you are converting from Points you have to remove the wire that runs from your coil to starter solenoid. This wire provided a full 12 volts to the coil when the key was turned to start the car. If you don't disconnect this wire you will pop your MSD box the first time you start your car. It happened to me and resulted in a lot of screaming, cussing and more $$$.

Also your factory tach may not work with the MSD box and distributor and may require a Tach Adapter from MSD. The original tach is designed to work with Points where as the MSD distributor has a magnetic pick up.

Use the MSD instructions and reference my post if you get confused. I don't believe they say anything about tossing that coil/starter, but it's a must.

Good Luck!

here is what you are looking for:

http://www.msdignition.com/downld1.htm
i just installed a MSD 6 AL in my 69 camaro.
its a piece of cake.
And with the probillet distributor its even easier.
just use the supplied wire harness and run the big red and black wires directly to the battery.

Dawgs, are you using a factory tach?

no AUTOMETER gage

but original DOES require a adapter harness from MSD

Which style tach was original magnetic pickup distributor voltage triggered tach
or a current triggered tach to points/amplifier or magnetic pickup? The reason I ask is the install instructions for the adaptor I was told to use an 8920 has 2 different wiring schemes.

http://www.msdignition.com/downld3.htm
Thanks

You can use the original tach, but it must be wired to the Msd6al box's tach output terminal, it DOES NOT get wired to the coil like the original points ignition system, in fact nothing goes to the coil + and - terminals except the orange and black from the Msd6al. If its wired to the coil it can ruin the tach. On original factory tachs in a factory gauge car, you only need to bypass the inline filter ( a small cylinder in the wire from the tach, looks like a condenser) Now I have heard (no first hand experience) that with repo tachs the filter is inside the tach, you would have to check with whoever you got the tach from or MSD on what to do in if the filter is inside the tach.

OK now I am getting more confused...I have a repo tach are you saying that I do not need the 8920 tach adaptor? This is the return email that I got back from MSD:

Dear Sir,

For your stock tachometer to function correctly, you will need to
purchase the 8920 tach adapter. It would be cheaper if you get pricing
and availability through an MSD Dealer. Our prices are 30 to 40% higher
because we are contracted not to undersell our dealers. You can obtain a
list of dealers who can provide you with prices and availability off of
our website at www.msdignition.com (http://www.msdignition.com) under AUTOMOTIVE DEALERS.

Thanks,
MSD Tech

I would like to knoe what needs to be bypassed in the tach before installing it.

Thanks

I'm only telling you what i know first hand. All Gm tachs are voltage triggered. Factory original GM tachs do not need a adapter, only to bypass the original inline filter. Repo tachs, if built exactly as the originals would not need one either. Just try wiring your tachs trigger wire to the msd6al tach output terminal. Even MSD tell you this. It can not damage anything. If the tach doesn't respond correctly, then you would need a adapter. All a adapter does is keep electrical noise out of the tach. From the Msd6al instructions, pg 7 ...........................

INOPERATIVE TACHOMETERS
If your tachometer fails to operate with the MSD installed you may need an MSD Tach
Adapter. Before getting an Adapter, try connecting your tachometer trigger wire to the tach
output terminal on the side of the MSD. This output produces a 12 volt, square wave (see
page 2). If the tach still does not operate, you will need a Tach Adapter. There are two Tach
Adapters:
PN 8920: If you are using the Magnetic Pickup connector (Green and Violet wires) to trigger
the MSD, you will need the PN 8920.


From the Msd6al instructions, pg 2 ...........................

TACHOMETERS
The MSD Ignition features a Tach Output Terminal on the
side of the unit. This terminal provides a trigger signal for
tachometers, a shift light or other add-on rpm activated
devices. The Tach Output Terminal produces a 12 volt square
wave signal with a 20% duty cycle.
Some vehicles with factory tachometers may require a Tach
Adapter to operate with the MSD. For more information on
Tachometers and MSD Tach Adapters, see the Tachometer
Section on page 7.
If your GM vehicle has an inline filter it may cause the tach to
drop to zero on acceleration. If this occurs, bypass the filter.

Msd 8920 tach adapter instructions http://www.msdignition.com/pdf/8920_frm22049.pdf

Msd 6al instructions http://www.msdignition.com/pdf/6%20series/6series.pdf

If you need more help or have other questions post back.

Thanks for the direction Greg I will follow your suggestions before buying anything else. I plan on starting the engine next weekend and will let you know what happens.

Thanks again.