Alright so like the title states, im trying to get my stock tach working by simply splicing into the original tach wire that used to go to the negative side of the coil. So i did that and plugged it into the tach output on the msd box and the tach is reading but i know its way off.. the car idles really low id guess around 700rpms or so but it reads around 1500 and when i rev it, it goes over 6k. Im not sure if it has something to do with it being a 4cyl cluster and its now a carbed 5.0 swap? Is there some sort of tach calibration or do i need something like the msd tach adapter? If i need the adapter id rather just buy a aftermarket tach.. thanks guys!