I have a 70 Chevelle, with the 454, and i ordered at Shiftowrks tach conversion, to put in place of non working clock. i know some people have said they have converted as well. Well i have a MSD ready to run distributer, with a SS blaster coil, and I cannot get it to work. the tach has 3 wired, a red for power off the fuse box, a black for ground, and a green to go to neg side of coil. I hook all of it up, and it idles fine but when you push down on the throttle, it goes backwards. i called MSD and they told me i have a bad tach, so i tried it on my monte carlo 72, with an HEI, and it works great!
I called MSD back and they told me I need an addapter, i bought that, and it still does not work, now they tell me i need to put on the MSD box, even thought i have a ready to run dist, Isn't there a cheaper solution?
the MSD tech had a pretty crappy attitude the last time i called, and told me i should not work on cars if i do not know what i am doing. So needless to say after buying 4 MSD systems i am taking my business elsewhere. He promised after insulting me that he send me a way to fix it in the US mail, that was 2 weeks ago. Please anyone, help....
i just want my tach to work. thanks
Will

Why don't you contact shiftworks and see what they say. Sounds like a problem with the tach. Could be that the ground and power are reversed but thats only a guess.

well i tested the tach on my monte carlo, with HEI, and it worked great. The instructions on the Shiftworks tach says do not put on MSD ignition , if i would have known that before, i would have never bought the tach. But i cannot believe that you have to have a MSn box to make a tach work