I have a 1990 4.3L. 190 HP. New 14X19 prop. Max rpm wot has been showing 3400. Found that the switch on the back of the Tac was dialed to 4cyl. Tried to change it to 6 but the tac does not work at all at that setting. At 8 cyl setting it reads way to high ( 5-6K- at 3/4 throttle).
Does anyone...
