Tackometer help!

Ever since the weather outside has gotten colder my tackometer has started to read about 1000 rpms higher than I know my engine is actually running at. Doing 60-65 miles an hour down the highway my tack reads 4000 altho I know by the rev of the engine its barely to 3000. I changed my distributor cap & rotor recently and ive changed my plugs. Im not quite sure how a tack works but thats all ive done to the car recently that could have made my tack read funny. Is it just time for a new gauge ? :confused:

Might want to check your connections, especially the ground for the tach....

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Originally Posted by Dave Severson

Might want to check your connections, especially the ground for the tach....

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The tach is a pretty simple device, counting the pulses at the negative side of the coil and dividing by the number of cylinders. A loose connection might indeed do what you're saying. Is it an OEM tach, or aftermarket? Can't see how cold weather could affect the gauge function...

if was put in after i had replaced the original motor, Ill check the connections when i get home, but if its cold the tack dosnt read correctly , but in the afternoons on my way home it does read correctly. I just dont understand

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Originally Posted by Slade1134

if was put in after i had replaced the original motor, Ill check the connections when i get home, but if its cold the tack dosnt read correctly , but in the afternoons on my way home it does read correctly. I just dont understand

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Sounds to me like you have a very old (like 60's vintage) tach that used an internal "coupling" that can be temperature sensitive. I'd say it may be time for an upgrade?

I fogured it out . Yesterday i was on my way to my house on the highway and was going bout 65-70 and it was at around 4000 which was of course wrong and i went to move it becauce it shivels up and down on top of my steering colum and it jumped down to just below 3000 which is where is should be. It was just a loose connection to the gauge. FIXED :D

Now that's good news!! Dave, you nailed it in Post #2!! Thanks for taking time to post that you found the gremlin.