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Old Today, 08:51 AM   #1
prateroad
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72 Chevy truck dash tach question

Original tach dash, Does anyone know what this hole is above wire terminals?
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Old Today, 08:54 AM   #2
1970cstblazer
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Lightbulb Re: 72 Chevy truck dash tach question

There was tape over it, but it is an access to the calibration screw.



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Old Today, 08:57 AM   #3
prateroad
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Re: 72 Chevy truck dash tach question

Anyway to test tach before I install?
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Old Today, 10:17 AM   #4
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Re: 72 Chevy truck dash tach question

Know any with a distributor machine? It would be the best way to check the calibration over the RPM range.

It's also pretty easy to hook the tach up with some temporary leads under the hood. You can verify the calibration with a new style digital timing light or a dwell meter.
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Old Today, 10:29 AM   #5
prateroad
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Re: 72 Chevy truck dash tach question

thanks for the help
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Old Today, 11:40 AM   #6
LockDoc
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Re: 72 Chevy truck dash tach question

Quote:
Originally Posted by prateroad View Post
Anyway to test tach before I install?

Just connect the wires to the tach output on an HEI or coil on regular distributor and positive terminal on the battery. I think you also have to connect a ground wire to one of the small screws on the back of the cluster to provide a ground for the the tach.

I can't remember off the top of my head which wire goes where.
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