Thread: Stewart Warner Tach to HEI Distributor

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A tachometer circuit is fairly simple in that it converts frequency to current to drive the meter. It is made up of a handful of resistors, capacitors, diodes, a bridge rectifier and perhaps a transistor (or two). In all likelihood, this tach was designed to operate with points and condenser and will not work without a filter to address the high frequency interference generated by the HEI.

This part should fix the problem (assuming the tach has not been damaged):

New Vintage USA 99004-04 - New Vintage USA Tachometer Signal Filters - Overview - SummitRacing.com

If your attached to this tach, it may be worth a try if you want to part with $33 plus the handling charge.

Good Luck,
Glenn

Thanks for your response. I was wondering if it needed a filter to handle the HEI. I think that I will pick up a new tach from Summit next time that I'm down there.
Great site, Thanks again