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Discussion Starter · #1 ·
OK, I've done a search, but I have not found my answer. I installed a 70SS dash, new dash and engine wire harness. I also have a complete MSD ignition system,(ignition box, coil & dist.) I ran the brown distributor wire to the tach port on the ignition box, but the tach doesn't work. With the MSD ignition, the stock coil wires are not hooked up. My question is, how does the factory tach get power? Is it the yellow wire that's attatched to the factory coil wire that goes to the + side of the factory coil? I checked an aftermarket,(autometer) tach and it works fine. I have the assembly manual, but it doesn't refer to the tach. Someone please help!!!

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1968 Camaro RS
1972 Chevelle SS clone
 

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Some factory tachs won't work with some MSD systems. You may need to get a tach filter add on for the MSD. The multiple sparks from the MSD confuse the factory tachs.
Power for the tach is through the cluster connector and flex circuit. Tach signal is via a single brown wire that runs through the firewall and to the negative side of the coil for points. If you have an hei distributor it would connect to the tach terminal on the cap.

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Steve Strasemeier (70SS 396, Fathom Blue/White Stripes)
My 70SS

[This message has been edited by Steve S (edited 10-11-2002).]
 

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<BLOCKQUOTE>quote:</font><HR>Originally posted by Steve S:
Some factory tachs won't work with some MSD systems. You may need to get a tach filter add on for the MSD. The multiple sparks from the MSD confuse the factory tachs.
Power for the tach is through the cluster connector and flex circuit. Tach signal is via a single brown wire that runs through the firewall and to the negative side of the coil for points. If you have an hei distributor it would connect to the tach terminal on the cap.

<HR></BLOCKQUOTE>

The MSD Tach adaptor should have came with your MSD Dist. in the same little bag with the different springs for re-curve.



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'70 SS 396
4spd, 4.10's and a smile
TC# 1341
ACES# 5388
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Life is a gateway drug that leads to Chevelle addiction.
 

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Discussion Starter · #4 ·
Thanks for the help guys, I installed a "MSD Tach Adapter" and the factory tach is working fine now.

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1968 Camaro RS
1972 Chevelle SS clone
 
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