Autometer tach bounces at idle

[Mrturner1]

My tach bounces from 750 to 3k when at idle, but if I rev it it's fine and if I hold it at and rpm about idle it's fine

[ray_mcavoy]

It sounds like the tach might be picking up some interference from the ignition system. Start by making sure the tach signal wire is routed as far away from the spark plug wires as possible. Also make sure the wire doesn't have any loose connections. If that doesn't help, you might have to add a filter such as this --> http://www.autometer.com/tach-filter.html

[Jonlopes]

I had that problem with a HEI distributor when I had the tach wire hooked up with a plain female spade terminal. The problem went away when I spliced in a pigtail with the correct plastic connector.

[Mrturner1]

Originally Posted by Jonlopes

I had that problem with a HEI distributor when I had the tach wire hooked up with a plain female spade terminal. The problem went away when I spliced in a pigtail with the correct plastic connector.

I got one of those plastic deals that snap onto the distributor so I think I'm ok on that part.

[Mrturner1]

Originally Posted by ray_mcavoy

It sounds like the tach might be picking up some interference from the ignition system. Start by making sure the tach signal wire is routed as far away from the spark plug wires as possible. Also make sure the wire doesn't have any loose connections. If that doesn't help, you might have to add a filter such as this --> http://www.autometer.com/tach-filter.html

What if the tach wire is away from spark plugs, but near plug wires? EDIT: just re-read your post lol

Thank you guys for your help, I hope to figure this out soon I'm tuning a freshly rebuilt 350 that I just got done breaking in