i'm driven along, mindin my own business and all of a sudden my I notice my Tach is jumpin around, usually only in the higher gears. If im just cruisin along at like 55 in 5th gear the tach will jump form 2.5 to 3.5 and back, farily quickly, and doens't stop till i down shift. WTF causes this.
its kinda funny though. haha

its a 85 GSL no mods basically

-chris

 

Is your engine actually revving up and down, or just your tach? If it's just the tach, the trailing ignitor could be going, as I believe that's where the signal comes from in the later cars.

Matt
1979 SA22C

 

If it is just the tach jumping, then it's either your trialing ignitor as MosesX605 says, or you are getting arcing in the spark plug wires. How are are your ignition wires. If they are old, I'd change them. Should solve your problem.