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Discussion Starter · #1 ·
Hello All,

I am installing a MSD Tach Adaper #8920 into my 1983 fox body that has the original tachometer. This will be hooked up to the MSD 6AL Ignition box. The tach wire that comes off the 6AL ignition box would only make my tach vibrate? So I bought the Adapter but it gives two sets of instructions, one for voltage based tachs and the other for current based tachs? Which does the original 83 tach use?

Thanks!!
 

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Discussion Starter · #3 ·
Still not working

Ok, so I followed the directions to a tee. It still does not work. I even decided to wire up the tach both ways that were pictured in the directions, nothing. All I get is a tiny "bump" in the tach gauge when I turn the key on.

My "original" coil wires were still intact, just wrapped in some tape over by the battery. I wired the adapter up as pictured with the adapter red to the original red coil wire and then back over to the red ignition box wire. The adapter purple/violet wire to the orginal coil green wire. I then took the gray wire from the MSD ignition box and connected it to the adapter white wire. Lasttly I grounded the adapter.Nothing, nada. Just the "bump" when I turn the ignition on.
FWIW, before I got the adapter I tried to go straight from the MSD box gray(tach output) wire to the original coil wires and thats when the tach would flutter. Thats why I bought the adapter. Now I even went back to see if I could get it to flutter again, nothing at all. Another odd thing about the wiring diagram is that it wants me to connct the Ignition boxes red wire to the adapters red wire and then to the original coil red wire. But the original coil wire is allready a hot 12 volt source once the key goes on, I don't know why I still have to access the ignition boxes red wire for?

How to tell if the adapter box is working or is no good?
Any suggestions welcome.
 

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Discussion Starter · #4 ·
I ended up sending everything back for a warrantee. When I received the new tach adapter and 6al ignition box, it all worked!
 
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