jumping tacho

[aussie_stingray]

hey everyone.. i have a problem with my '76 vette.. the tacho seems to be jumping in the rev range.. i dont know wot causes it.. as it does it every now and then.. and get very annoying!!.. could it be a simple short or along those lines... any help is appreciated
cheers from Australia!!

 

[80convertible]

I had the same problem before the tach quit. It turned out to be corrossion on the circuit board. I cleaned everything up and never had the bounce again.

Jim

 

[Shawn's 78]

I also had the same problem on my 78. Turned out to be the coil. I replaced that and now it moves smoothly 0-5500rmp up & down (even at WOT).
Shawn

 

[cruzer99]

Aussie,
G'day...I was going to say Dist. or Coil but sounds like corrossion could be a third option. I guess you should check them all.

Good on ya...mate.

Was down under to see a F1 race a few years back and some mates in Adelaide.

 

[SLICKMAN]

It also could be the tach filter!! You can see it mounted on the intake right near the dist... If this filter is bad, it will cause the tach to jump around, these are not available for replacment so, here is a diagram on how to make one..
Tach Filter

 

[page62]

Actually, there is a tach filter for sale, and it's only $17.50! It's a non-OEM unit, but at that price who cares?

http://www.rodneydickman.com/retail.html
Click on Electrical, then click on Tach Filter

 

[SLICKMAN]

Thats great!! If you use my diagram, You can make it for about $4 :crazy

Actually, there is a tach filter for sale, and it's only $17.50! It's a non-OEM unit, but at that price who cares?