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just installed a msd 6a box,blaster coil and pro billet dist on my 1985 mustang. tach does not work. removed msd box tach works with box out of loop tried running new wire from tach out put to tach wire still doesnt work. the car is equiped with eeciv (a9l) has anyone had this problem?
 

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Do you have the tach hooked up to the factory harness? If it is you need to move it to the green wire coming out of the MSD box. (I think it is the green wire)
 

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Call MSD they have a item you will need to put in between the box and the harness ( or somehting like that) I had the same problem on my 85 with an MSD box, they sent some kind of voltage regultor or supressor, sorry this was over 10 years ago my memory does not serve me well.
 

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Dark 7068 is selling a tach adapter in the classifieds. WIll that work for this guy?
 

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I have the same problem (73 Mach1) ... got the adapter ... still no work.

These tachs were made to work on the old "Points" style ignition system and I have a feeling the power spikes from the "electronic" higher voltage ignition systems can "fry" the inerds of these old tachs.

I'm listening too ... would love to get mine back "on line"




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Larry Madsen
Las Vegas Nevada



<font size=-1>[ This Message was edited by: MonsterMach on 5/19/02 10:39am ]</font>
 

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The problem is the tach is not seeing enough pulse. Normally it is fed from the coil, but once the MSD is installed the iginition module is just triggering the MSD, not the coil. You need the tach adaptor MSD-8910 in Summit catalogue. It connects across the the input wires to the MSD(just two wires). Same also applies to the older points systems, I have that same adaptor with a Crane HI-6, on my '69 Cobra Jet. Factory tach works fine.
 
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