BLDun

I have a '76 with the original 350 although it was sent out and rebuilt a couple years ago. It has never had a tach filter and didn't seem to be a problem. I replaced all the original gauges with aftermarket including the tach and speedo. That was about a year ago or so. Yesterday I was driving and the tach just quit working. Dropped down to about 500 and bounced there. At idle it shows nothing at all. I looked for a fuse but can't find one that has tach on it.

Any ideas? Do I need to put a filter on it?

Thanks
Barry

0Willcox Corvette

Hard call there.. I'd always run one. But you have an aftermarket tach I assume and something has probably spiked the board inside. The problem is (and judging from your post) you have an aftermarket tachometer so you'll need to contact the manufacturer and see if the tach requires a filter.

If you have a factory tachometer in the car the you probably just need a board to fix the issue... The basic function of the filter is to prevent spikes and to knock the edge off the square signal generated by the distributor. The factory board and our reproduction board will read either a square or rounded signal so this explains why you never had an issue until now.

-Willcox

BLDun

Yea it is aftermarket. I put all autometer gauges in sometime ago. Wouldn't happen to be the ground would it? Is there a way to check to make certain there is a signal going to the tach?

0Willcox Corvette

Not without a scope.. But the best you can do is ping the wire from the tach to the distributor connection.. it'd be highly unlikely the distributor isn't sending a signal. If the tach is moving at all... then it has ground. I'm sure their tach works off a similar schematic as ours.. .Power, Ground and signal... No ground no movement. Might it be just a loose connection? I'm not sure you'd have to check that tool.

I wish I could be of more help...

Willcox