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Discussion Starter #1
Could someone please provide some insight into permanently bypassing the factory tach? I am installing a Dakota Digital VHX Dash and Edelbrock Pro-Flo 4 fuel injection at the same time so of course I will no longer need the factory gauges. I don't want to reach a point where I am ready to fire up the car and it does not run thinking it could be an install mistake I made with the Pro-Flo 4 but in reality it was because of incorrect bypassing of the factory tach. I can find information on taking the tach out of circuit by splicing in a 12v power source route but I need to eliminate the factory tach altogether. Is it a simple matter of cutting the male/female banana connector off the tach wires and then splicing them together and plugging that back into the banana connector coming from the main harness? Or probably better just cutting the banana connector wires off the main harness and soldering them together? Any expertise would be appreciated.
Thanks, Brian
 

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Just leave the factory tach unplugged. The VHX will connect to your coil or MSD whatever is running the FI.
 

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What year car? On early 65-66 cars you need to unplug the tach from the 16 and 16A wires and then plug those two wires together.

Check Averagejoerestoration.com for the wiring diagrams.
 
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Discussion Starter #6
The PF4 will have a tach output that can go straight to the new dash's tach input. There's a sensor in the PF4 distributor that gets rpm from the cam.

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Thank You. I have that Tach lead ready to go. VHX arrives today. Just was not certain that something had to be grounded in the Main harness as well.
 

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Discussion Starter #7
What year car? On early 65-66 cars you need to unplug the tach from the 16 and 16A wires and then plug those two wires together.

Check Averagejoerestoration.com for the wiring diagrams.
That was my concern. I have 1969 Mach 1 with the factory tach. Just wanted to make sure that there was nothing I had to do with the factory harness to allow the car to start? As I stated when I removed and disconnected the entire dash the car would start then die immediately. I finally figured out the tach had to be plugged in for the car to run. I am not the best at electrical and just wanted to make sure that the wire coming from the Main harness to the tach could be just left unplugged without it effecting anything? I read some technical information from TachMan that stated you needed to jumper that Main harness wire together to run the car. Between the Dakota Digital VHX and Pro-Flo 4 being connected I assumed nothing needed to be done and I just could leave the Main harness wire unplug for the remainder of its life with no jumper? I get that the tach wire coming from the PF4 ECU plugs into the VHX tach terminal. Thank you so much for your time.
 

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After removing the factory tach, join the two wires that went to it, together. This will complete the circuit to the coil in run position of the key.
 
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