i recentley did an engine swap from a v6 to a smallblock does anyone know what to a set the tach adjustment dial on the back of the tach to for a v8 its set on 2 now the tach is reading high when under power thanks

Don't know if all models are the same, but mine says:
4 cyl - 1
6 cyl - 2
8 cyl - 3

correct above ------- Its called pole setting. you have to use a small blade screw driver and gently depress the pole setting dial and then turn the dial to correct numbered position, It has to click and be correctly set on the that position. They can be a bit touchy to get set exactly. Small blade screw driver works the best.

Also FYI for whomever --- there is another pole setting added in the MIX its number 4 called the 12 pole for Outboards. Also there is 5 and 6 poles on many other tachs, do not set it on any of those 4 thru 6. Number 3 pole for 8 cylinders.

If set on the wrong setting and or just a fraction of a hair off from the correct pole setting - your rpms can or will be totally wrong - sometimes waver all over the place as well.

thanks its on 3 i verified rpm with tach in my timing light