tach problem

cfelton · #1 03-05-2007, 11:20 PM

Ive got a 77 v with a 170 I/O with an original tach. It works ,but its about a thousand RPMs too fast. Anybody know if theres a way to reset or recalibrate this thing,or should I just buy another one. Its got four tiny wires coming out the back.

spareparts · #2 03-05-2007, 11:47 PM

look on the back of the tach, it should have a dial with 4cyl, 6cyl, 8cyl, 6 pole, 12 pole written on it, turn it to 4 cyl and you should be good to go

cfelton · #3 03-06-2007, 12:39 AM

thanks spare, ill look tonight when i get home from work. I dont think its gotta selector switch on this one but ill look to be sure. The tach in my old drag car has a dial like you mentioned.

spareparts · #4 03-06-2007, 10:43 AM

sometimes it will have a plastic or rubber plug you pull out to access the dial, some have dip switches to set up the tach, if you can't fiind either, ditch the tach and buy a new one

cfelton · #5 03-06-2007, 01:17 PM

well, I took the tach out this morning and found it has some small adjustment screws for 4,6,and 8 cyls. I turned the 4 cyl screw down and turned the ignition switch on and it droped to almost zero. It was too cold to hook up the water hose and try it but soon as it warms back up Ill give it a try.It dosent have a dial, just a jumper wire and 3 pins for 4,6,or8 cylinders.It was connected to the 4 pin. Hopefuly its close, if not I know where to adjust it now. thanks spare

cfelton · #6 03-07-2007, 06:52 PM

Well,I got my pertronics yesterday and installed it this morning. It was a piece of cake. I had it running and timed in 15 minutes, I also made a bracket and mounted my new perko battery selector switch. I made new cables and hooked up one battery. It purrs like a kitten now. That pertronics kit makes a lot of difference! Hopefuly Ill get to try it out friday, weather permiting.