I'm working on a 90 4.0. This weekend I plan on converting it to an open style cooling system and adding an electric temp gauge (only have idiot lights).

I bought a later model thermostat housing so I can use the sending unit port for my gauge. The gauge came with a brass fitting that is 3/8" male outside and 1/8" female inside. I thought that I read the sending unit port was 3/8" as well. Is this accurate? Because it does not even start to thread, immediately locks when I start. I can probably force it on but I do not want to screw up the housing.

Should I drill the two holes in the thermostat? I have heard it's advised to place a hole in the 12 and 6 o'clock positions. Is this beneficial for the open style cooling as well?

For the converter I'm just using the filler neck and over flow bottle, keeping the factory radiator.

 

Well this housing is toast. I used the 3/8" adapter that came with my B&M temp gauge and thought maybe I should give it a little umph since it wouldn't thread right. It ended up cutting the threads on the housing, so either the housing was not 3/8" like I read or this one was a defect. I verified with other 3/8" adapters that would not work either, definitely something with the housing.

 

got pictures ?

 

of what?