I know it's a very common problem but i'm not sure how to fix it. I don't have a direct fire setup...just installed 2 msd boxes in addition with already existing msd coils. Started the car up but no tach.

MSD manual talks about some kind of a adapter in case that happenes but it's for other domestic cars.

Anybody ran into the same problem? What do i do to fix it? Any info greatly appreciated.

 

the same happened to me and I cant figure it out. Any suggestions?

 

Plug the tach wire into the tach output terminal of the MSD. It worked for me when I tried it. It's just a pull-down quare wave (I believe). I also have a dead tach in my Cosmo, so anything's possible.

 

jeff is right. you have to connect the tach wires directly to the msd box single male connector.

 

That sounds easy enough but where does the stock tach wire plug into?

Also if i have two boxes, i would have to plug it into the leading box?

 

stock wire is connected in the trailing's negative terminal. you can connect this on either box.
ie. in my rx-3, the stock tach is connected in the trailing but my autometer tach is connected in the leading. its hooked up this way to give me a warning signal in case the stock trailing goes bad or the msd.

BTW, this is using direct fire and one msd 6a box.

 

Wackyracer, is that your car in the picture? That rx3 looks magically delicious.

Thanks for the info everyone...but i can't get the car started anymore..doesn't matter what i do.

I'm going to open a new thread for this one.

 

One more thing you should know. The square wave signal is around 12V, as is the rest of the electrical system. The tach is designed to take this signal. However, when you hook up an MSD to your car, you can't simply put the tach signal wire on your coil anymore. The CDI output of the MSD is way too high for the stock tach and may burn it out (the MSD has never been in my Cosmo, but anyway). Most people only get one MSD and hook it on their Leading side, so the Trailing side remains the same (with tach wire to boot). Since you're going with another MSD on your Trailing, you WILL have to hook your tach wire to the little male dude on the MSD.

Hey, good luck with starting your car. Just remember that an MSD box can fail at any time due to space dust and moon rocks, or whatever.

 

Man, i hope not they were only about $350. Now that i think about it i wish i did get only one box.

But yeah, i defenetly might need some kind of luck with my new problem.

 

yes, thats my pos RX-3. Currently running a 13-B big street port with 48 ida. but switchng to 13-B big bridgeport with 51.

 

13b bridgeport rx3

 

Thanks. The only problem is I only have 1 set of axles for spare and I kept on breaking the u-joints. I have looked into other rear end but after speaking with Robert @rotary shack and my other bro, Ben Alameda @ Ben Alameda racing, a ford 8.8 is the best to go. Its lighter than a 9".

 

What is your 1/4 mile time? Probably like 12's or something.