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71K20chevy · 05-21-2014, 10:41 PM

One wire goes to negative side of coil (TACH terminal in your case of HEI) and the other goes to IGN UNFUSED on the fuse block. The cluster needs to be grounded good as well.

My truck has HEI, my factory tach is wired exactly like this and it works fine. Is your tach fried?

05-21-2014, 10:41 PM	#3
71K20chevy Registered User Join Date: Jul 2012 Location: Ft Wayne Indiana Posts: 1,205	Re: tach. question One wire goes to negative side of coil (TACH terminal in your case of HEI) and the other goes to IGN UNFUSED on the fuse block. The cluster needs to be grounded good as well. My truck has HEI, my factory tach is wired exactly like this and it works fine. Is your tach fried? __________________ 71 K20 64 GMC mud truck