Finding tach wire in engine bay

[mimccloskey]

I started to install a MSD system in my 1970 914 that has carbs and a 009 back in the fall. Well the weather is getting nice and I have gotten motivated to finish the install. The box is in and the car runs great, but my tach doesn't work. I have the tach adapter from MSD installed. The prior owner did some really crappy rewiring, and I have no clue (can't remember) where the tach wire comes into the engine bay. Once I find the wire, I also need to know if that wire goes to the MSD tach out or joins the other wires. If you have done this same install, your advice would be greatly appreciated!!!!

mimccloskey@starpower.net
Arlington VA

[SteveStromberg]

It is in the harrness with the Coil hot lead. Black with red strip. see http://www.pelicanparts.com/914/parts/Electrical/914_electric_73C.jpg

the coil wire and tach wire are on the very bottom of the page. Look for 1,2,3,4 thats the dizzy next to it is the coil. Steve

[Dave at Pelican Parts]

The tach lead is black with a purple stripe, not red. It goes from the tach, through the center tunnel to the relay board, then from the board to the coil (-) connection. That's the same connector that the wire from the points goes onto. The purple can be tough to see, but it's there.

The MSD will hopefully have a "tach out" pin. Try hooking the tach wire up to that. If no joy, then hook it to the transformer (the "tach adaptor") and hook the transformer to the "tach out" pin.

--DD

[Bee Jay]

Does the tach wire plug into the MSD tach pin, or the - coil lead? The tach adapter has a red and white wire and plugs into the msd red and white wires, according to the insructions for the adapter. The instructions don't say.
Bee Jay

[Dave at Pelican Parts]

The tach wire should most likely plug into the tach pin.

If you don't have an MSD, then you'd plug into the coil (-) terminal.

--DD

[CGNJ]

I run a MSD-6. I also purchased a tach adapter. Wouldn't work, so I tried the tach output of the MSD-6. It worked on my car. I have run it like this for about 2 years. The wire is the black with purple tracer.

Carlos

[Bee Jay]

OK. I tried four different ways this weekend.
1. MSD in, no tach adapter, tach wire left on - coil.
Car runs great, not tach.
2. MSD in, no tach adapter, tach wire plugged into MSD tach pin
Car runs great, no tach.
3. MSD in, Tach adapter in, tach wire plugged into MSD tach pin.
Car runs great, no tach.
4. MSD in, Tach adapter in, tach wire back at - coil position.
Car runs great, no tach.
I'm running the Pertronix ignitor points eleminator too. Maybe that is the problem. The Monster tach is looking better and better.
I'm gonna call MSD when they open up.
Some interesting notes though. Even though the tach isn't working yet, I took it around the block a couple of times, to see if the MSD made any difference. Well the popping and sputtering I first blamed on leaking heat exchangers, and then blamed on the carbs, went away. No popping and spitting. The AF meter leaned out a lot, and I get LOUD backfiring on long over runs in gear. What'sup with that? Do I have to rejet with MSD. I didn't have to on the Vette.

Bee Jay
I'm gonna move this to a new topic so we can get more people helping.