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Old 03-29-2002, 08:19 PM   #1
Ironhorse
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Question Tach Test?

Can someone with a factory dash tach tell me how to test mine for operation before I put it in the new bezel and then in the truck? Have the tach, fact. GM printed circut, and the original harness. Heavy red wire with two clips or connectors, one has short pigtail connector and then a connector.(12 Volt power which hooks to 12 volt source unfused at fuse block), heavy brown wire (Hook to Coil Positive or Tach port on HEI) and then what? Does the tach use a ground? There is a threaded stud or attachment above the connections on the back of the tach.
'Preciate any help before I smoke test this thing. Got lucky couple years ago and found it in a truck at a 'yard for $15 for complete dash. Just been waiting until truck gets a complete re-build before I put it in. Thanks for any and all help.

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1971 Chevy 1/2T 4x4 LWB 350v-8
Wellington, Ks
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Old 03-29-2002, 10:04 PM   #2
71Chev
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The tach is grounded through the metal gauge housing. The case is grounded through the wire harness. To test it with out pluging in the dash harness, you have to hook up a ground wire to the case and the dash, and hook up the hot to the tach and to the distributer.

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Old 03-29-2002, 11:08 PM   #3
Rod
 
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I just hold the metal case of the cluster against the rad cradle... use the tach harness to supply the power and put the brown wire to the distributor. Rev it up some watch the tach move. Some stick some dont move... taken a few somwhat apart to get them working... its fun.
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