Chrysler 1975 120HP Water Temp Sender Thread Size

[Ghatz]

Hi guys.
I'm looking to buy a water temp guage for my old Chrysler 120HP and was wondering what the standard thread size is in the thermostat housing, that a temp sender screws into?

If someone could let me know, I'd really appreciate it.

I'd also like to connect a tachometer to the boat but have heard it's a little complex to wire up? Again, if anyone can assist with a wiring diagram or let me know how to wire it, that would also be greatly appreciated.

Thanks,
George

 

[Frank Acampora]

Re: Chrysler 1975 120HP Water Temp Sender Thread Size

The temp sender at the top of the head is American 1/8 NPT (national pipe thread). It is usually in the head itself, not the thermostat housing. If hopwever you have the head with a tube down it and thermostat on top, then I believe it is in the housing. (Long time since I have seen one of those heads) If you can only find Metric senders, it can probably be re-threaded. If not, there is usually a boss on the block just behind the head that can be drilled and tapped.

Your 1975 is a distributor ignition so standard tachs will work. There will be three terminals on the back: Signal, Power, and ground. You take signal off the white wire of the CD boxIt will be unused under the dash. Power is taken from the "I" (or "A" if the switch is newer) terminal of the switch so the instrument is turned off when the key is turned off. Ground is grouned to any common ground or the black wire in the cable which is also usually not used. Set the switch in the back of the tach to "4"--four power pulses per revolution.

If you want to use the light, you simply attach that hot terminal to your light wiring.

That's it simple 15 minute job (after the tach is mounted in the dash.

 

[Ghatz]

Re: Chrysler 1975 120HP Water Temp Sender Thread Size

Thanks for the info.

Very helpful.

Thanks again!