Big Daddy Spo

Any problems running a factory 1964 Cutlass console tach with HEI? I have the original tach in my 64 Cutlass, but am running HEI on my 350 SBO. The tach only goes to 2000 rpm then sticks there. Fine range of motion from 0-2000 and reads correct at idle at 625 rpm. Anyone experience this problem and possible fixes?
Thanks,
Steve

Run to Rund

The problem is sine wave vs. square wave. You need a tach adapter.

Big Daddy Spo

Found a GM style filter on eBay. Hope to get it installed today. Will keep everyone updated if it takes care of the problem with the tach signal when running HEI.
Steve

matt69olds

I used the factory tach in my 69 with HEI, HEI triggered by a MSD ignition box, and now with HOLLEY EFI. It’s worked just fine with all of them, or it’s been equally inaccurate with all of them.

Big Daddy Spo

Thanks, good to know. I installed the filter today and it basically killed the signal to the tach all together. I will check the wiring, but I think it might be something in the tach. I have another console tach that I will try out, as well. More to come.


Steve