On the stock tachs like the one in my 88 lx. Is there a switch on the back of the cluster to change the tach so it will read 4/6/8 cyl. My car was a 4cyl. Now it is a supercharged v6 and my tach is way off. I was hoping it was as simple as pulling the cluster and changing a switch?

anyone know if this is true. If not is there anyway I can make a stock tach work so I dont have to have to have a dead gauge on the dash.
thanks
Doug