Join Date: Mar 2002
Location: Austin, TX, USA
Re: Bench Testing Tachometers
It's nearly impossible. For one thing, it takes a variable frequency source and that source will have fairly hostile voltages present. Not easy at all to simulate even with a frequency generator. About the only thing I can think of is to use a distributor machine and connect the tach to a distributor while it's spun up to various RPMs. Perhaps even easier than that would be to wire them up to a car. Beware however that many of the old OEM tachs were meant to work with breaker point ignition. Using an electronic ignition as a tach signal is hit or miss - it may work and it may not.
68 Coupe, 350 w/ Edelbrock Performer RPM heads, cam, intake, 700R4, Dave's small body HEI