Hot Rods Tach Question

Is there an electrical test that can be done at the disti tach connection to test for a signal? My tach is not working HEI ignition. I have checked all connections and made sure all are good and in the right place. Last option is to pull the top off the disti and check the yellow wire connection.

 

try another tach?

 

If it's a vintage tach originally used for points-type distributor, it won't work with electronic distributors such as HEI or Pertronix.

If it's an old Sun tach or a factory original tach, AutoInstruments in Virginia can convert it.

-Brad

 

try another tach?
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OR try this tach on another dist.

all that is needed is the ground wire and dist wire ,

whole the tach in your hand and crank the motor over and Bingo !

 

I keep hearing on here that the old Sun tachs will not work on HEI. The one I bought new in 64 and ran on 6-8 HEI's must not have gotten the word as it worked fine.

 

The best I know, the tach output on an HEI is equal to the negative terminal on a coil for your signal, aside from required 12v positive and negative. And if I remember correctly, that's what my new tach box showed in it's instructions in 1986.

 

New tach fixed it. Thanks for the help guys!