Ok so I installed my aftermarket Tach today.... it looks great, but I dont think it is very accurate. It has the switch on the back for 4,6, or 8cyl. It was way off on 4cyl sounded like my engine was gonna blow and it was only reading about 2.5k RPM, switched it to 8cyl (i have a 4cyl) it seem a little more accurate, but im prety sure my redline isnt 4k RPM, that would just be silly! I lowered the idle all the way to where my truck was just barely running and it said i was at 1k RPM still. Im wondering if maybe I hooked it up to the wrong spot on the coil.... the back of the coil only has the one post, but then right next to the coil you have a white box with 2 more posts, i hooked it up directly to the back of the coil. See pic below.
Here is the Gauge though:
Bookmarks