What has to be done to the stock 914/4 tach to allow using the HEI distributor signal to accurately show engine revs? I have heard adding a resistor, but not clear? Tried a cheap aftermarket tach, worked one day and died. 2nd one never worked. Is there something from the HEI that is unique?

See the following 2 options for converting a 74-75 tachometer. (Earlier tachometers are different - see pdf attachment). Nothing special required with an HEI distributor. I converted two tachometers - one using the resistor method and the other using the capacitor method. Both methods worked. The problem was that both tachometers were crap to begin with - they had no damping and would grossly over-react causing the needle to swing back/forth until it settled down.

I finally gave up and got a tachometer from bigmarkdesign. Very nice. $150.

The damping of the 914 VDO tach is not a electrical adjustment. Its set on the back of the meter movement. A small pin is set in silicon grease and dries out over time and causes the swing. Its a pretty easy fix after you have done a couple of them.

Bob

What is the procedure for the fix?

Nick

I have RH converted tach you can have for 40 + shipping if your interested please PM me. It cost me 100 + at the time.

Paul PM sent

Hope y'all can help! I have a tach dated 9/74… the one with the calibration pot. I want to convert it for v8 use. I am looking in the same area as in your photo. My tach already has 3 resistors mounted on the board! As far as I know this tach came out of a 4 cylinder car. What gives! It does have a 0.22 capacitor in place. Somewhere around this forum, I also saw someone who replaced the 0.22 uf cap with a 0.10 uf cap with the same results. Any thoughts?
Thanks!

This looks similar to the picture above, but see if this helps...... It worked perfect on mine....

Send it to Mark. It's way too easy that way.