New guy with question about temp sensor

Hello all. I'm new to post but have been reading and absorbing all I can for info about my 1958 Chevy Apache. I've had it a couple months now. Once I bought it I found out it has a '55 235 in it. The temp gauge in the '58 dash is electric, with the lead hanging into the engine compartment, unused. The temp sender in the head is mechanical. I would like use the electrical gauge, but don't know what electrical sender to buy, and where to put it. Any help is appreciated, and let me know if there is already a post about this. I looked and couldn't find it. Thanks in advance. Keith

 

Hi. You would remove the mechanical and just screw the electrical there. You should be able to go to an auto parts such as Oriley's or Napa and get one as I believe the threads in engine are pretty standard for this. You could take the mechanical out and take it to auto parts for a thread check. It will be a pipe thread. Just guessing but it likely is 1/4" pipe thread.
Jimmie

 

Thank you Jimmie. I took the nut off and it fits into a brass 3/8" flare female fitting. So I guess a 3/8" replacement. The problem now is that I cannot remove the bulb like part from inside the head. I can grab the aluminum part sticking out, but when I try to pull it out is very stuck. I included a pic of what is left in the head. The brass piece is what I think is stuck. Not to mention it is difficult to get to. Thanks again.