Technicle help with Tachometer

Have a 540" blown alcohol chevy with a Mallory Super Mag III *External coil*. Old tach (magneto specific) went bad. Autometer does not make these anymore. Bought new tach & converter box. Tach & recall reading very erratic. I was advised not to bandaid this problem with suppression wires as autometer recommends. I cant be the only one with this problem. Please Help!

 

Jim I too have this problem with the same set up as you.No recall (playback) erratic sweep of the dial so I just use the tack for setting barrel valve and idle.I have changed wires no change,as long as performance is not affected hell with it.Dave

 

Go to FIE and read the tech articles. Basically GROUND everything and then when you think you are done GROUND more stuff. lol

 

are you using the tach convertor with a brown /yellow and a brown/orange stripe wire?

grounds..are very important!..... i would make sure you have the heads grounded together..then from that point to the coil ....then to the chassis ground. then put your battery and tach adaptor ground there. that way , we have now provided a true path to ground.

also, have you checked the ohms per foot on the plug wires yet?

 

Tach Issue

I have the same setup (or had) I ended up just removing the whole thing because I just couldn't get the tach to settle down. I found I wasn't looking at it anyway.

My 2 cents