Tach Question -L72

[Larry S.]

I have a 1966 L72 BB and wanted to attach a portable tach (dwell-tach tester) to assist me when checking the timing curve. The car has transistorized ignition. I connected the red cable from the tach to the coil "-" (smaller wire) connection and the black cable to a good ground (as suggested in the dwell-tach manual) but the tach doesnt work. I tried a second dwell-tach tester, and it doesnt work either. What am I doing wrong??? Thanks for any help on this.

[Stuart F.]

Re: Tach Question -L72

Hope someone will help you today. I too have an old tach/dwell meter and wonder what I can use it on today. I have Pertronix Ignition conversion.

Stu Fox

[Larry S.]

Re: Tach Question -L72

Yes Stewart,
I am not sure if I connect the tach (red clip) to the negative terminal on the coil (the same way that I connect it on a points-condenser distributor) or somewhere else as the distributor is transistorized. Thanks for your comment.

[Duke W.]

Re: Tach Question -L72

IIRC when I had a TI on my car, my ancient mid sixties vintage tach/dwell meter functioned with the standard connections.

Make sure you have a good ground - measure resistance between your test ground and battery negative post to make sure it's zero.

I know my old test tach works on the HEI, which has a simliar primary current wave form to the TI.

Duke

[Larry S.]

Re: Tach Question -L72

Thanks Duke, I will check it out as you suggest.