MSD Tach Adaptor

[jabb]

I have the MSD Tach adaptor 8920 for magnetic pickup.....
I am a liitle confused about the wiring.... It has 4 wires....

Red, Blk I know how to wire.....
The White and Purple I am confused about....
In the directions it says the purple is not used ???

Also where do I tie the Blk and purple tach wire into.....

This is a replacement for and 82 SC that was running a 6 pin permtune box.

Thanks

[A Quiet Boom]

The white wire goes to the tach output of the MSD ignition box, the purple wire goesd to the blk/purple wire from the tach. Which MSD box are you using?

[jabb]

I am using the 6AL MSD.....

Where does it pickup the trigger from what is happening in the distributor. I was thinking the Blk/Purple would have to also splice into the green wire from the distributor ??

The Car starts and runs fine just need to figure out how to wire in this Tach.....

[si2t3m]

Hi Joe,

I'm running a MSD6A box and didn't need a tach adaptor.

3.0L using the magnetic pickup wiring (violet & green) to trigger the MDS box.

Wire connected in the tach output of the msd box going to the tach (tach is a 73 from a 911).

HTH

Marc-Andre Morin
70 914-6 conversion 3.0L Webers

[StanChung]

Marc-Andre,

I'm getting ready to install an MSD into my 1973. Any advice? On the site, there seems to be so many opinions. Any tips? Where should I go for the clearest instructions. I don't want to screw it up. Thanks.

[A Quiet Boom]

The consensus that I got was the the tach might work when connected directly to the MSD box but would definately work with a tach adapter. On the end of the 6al where the violet and green wires come out there is a spade connector for the tach output which usually goes to the tach (black with purple strip on 911s) to wire up the tach to the MSD using the 8920 adapter connect the white wire of the 8920 to this terminal, the violet wire to the cars black and purple wire, red to power and black to ground. DO NOT connect the tach to the coil or the mag pickup. For the record, I've hooked up MSD components on many different vehicles and my P-car was the first one that needed the 8920, my tach did not work without it. The 3.0's green wire from the distributer is coaxial, it has a sheath and a core wire, these connect to the violet and green wires of the MSD, I'll have to look at my diagram to be sure but if I remember right it was the green wire to the core and the violet wire to the sheath. Also be sure to connect the heavy red wire to the starter terminal that the battery connects to and the smaller red wire to the ignition switch. Make sure that the heavy black wire is grounded to the engine. The white wire of the MSD is not used but can be connected with a normally open switch to ground as a kill/anti theft switch when the white wire is grounded the car will not start.

[StanChung]

Thanks for your detailed reply, Quiet Boom. Very helpful.

Does anyone have a picture of one installed? Is it difficult
mounting it?

[jabb]

Got it working with the adapter.... Marc tha Tach I am using is an 82 tach and needs the adapter to work....

Other notes for the Magnetic pickup you need the MSD adaptor 8920 for the tach not 8910 the 8910 is for points.

The Grren wire from the distibutor gos to the Grren wire on the MSD and the outer shield part of the green wire goes to the purple lead..........

[jluetjen]

I posted a wiring diagram of how I installed the MSD into my caron this thread. I believe that there was a change in the 911's Tach technology somewhere along the line, and so this set-up may not work for a lot of cars. I don't know when the tach design (and as a result the wiring) were changed.