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Old 08-02-2012, 10:28 PM
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Tachometer question

Why does my rebuilt tachometer not register more than 1000 RPM
even though I rev up to 3,000 or so? It hardly moves.

This in on a 75 Pontiac Trans AM.

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Old 08-03-2012, 05:56 AM
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It's broken.
Check the wiring too, but i'm going with broken.
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Old 08-03-2012, 05:56 PM
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Quote:
Originally Posted by walt03 View Post
Why does my rebuilt tachometer not register more than 1000 RPM
even though I rev up to 3,000 or so? It hardly moves.

This in on a 75 Pontiac Trans AM.
FIRST thing I would check is the circuit board. If it looks OK I'd next try bypassing the filter.

IIRC the case on that tach was steel. If so, it should be grounded. When the key is turned on the tach needle should return to 'zero'. That would mean it's getting power and it is grounded.
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Old 08-04-2012, 12:30 PM
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It turns out the rebuilt tach was for a points distributor and this is HEI so its going back to the vendor.

thanks for your comments
Walt
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Old 08-04-2012, 02:11 PM
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Quote:
Originally Posted by walt03 View Post
It turns out the rebuilt tach was for a points distributor and this is HEI so its going back to the vendor.

thanks for your comments
Walt
I'm glad you figured this out so quickly, Walt. Is there an external ID that tells if the tach is points or HEI? I have the instruments from a Firebird (year unknown) in FL but I can't say I remember what type ignition it had.

Thanks, Mark
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Old 08-05-2012, 08:24 PM
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Originally Posted by cobalt327 View Post
I'm glad you figured this out so quickly, Walt. Is there an external ID that tells if the tach is points or HEI? I have the instruments from a Firebird (year unknown) in FL but I can't say I remember what type ignition it had.

Thanks, Mark
There is no indication. However this reputable could of asking more questions, like does it have HEI? You better repeat more than once what you have and what you want anymore. Parts guys aren't really mechanics or car guys anymore and frankly I find that it's always someone someone just trying to sell parts and not selling you the RIGHT parts.

Pontiac started using HEI late in 1974 production from what I've read and in the entire 1975 production year going forward. When in doubt keep asking questions though>
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