I have put a carbureted 460 in my 92 F150 in place of the 5.0 that came in it. Everything works fine except for the tachometer.
I tried hooking up a wire to the negative side of the coil like the 5.0 was wired but it did not work (the computer is still installed). Then I removed the instrument panel and determined which wire carries the signal to the tach. I then ran a bypass wire to the negative side of the coil. The tach now works but it reads about 20% high (at 60 mph actual RPM is 2700 but the tach indicates about 3400). Has anybody "been there-done that" yet? Any suggestions?

 

Hello, i wish i could help you with your problem, but i kinda cant. But i want to do the same think to my 92 f-150, it has a 302 fuel injection, with a 5 speed. how hard is it and what all will i need to change to drop in a 460?

 

John, does the tach have a switch on it to change from 6 to 8 cylinders? If it does, try spraying some electrical contact cleaner on it and move switch back and forth. This works for aftermarket tachs, not sure about factory tachs. Don

 

I can answer for the 80-86 factory tachometer which should be the same if 0-6K RPM. On the back of the tachometer should be four terminals which are marked as follows

Right side B G
Left side 0 8

These tachometers were internally identical to all series Fords with the exception of the face and mounting bracket. Applications were used for the I4, I6, and V8 engines. B is battery power, G is ground 0 is either a shunt for I4 along with 8 or used alone for I6 application, else use 8 for V8 leaving 0 open.