Need a 3/8 NPT temp sender, or am I SOL ???

[Green Machine]

Putting a newer engine in our 1970, thought I had everything for the swap, but I just noticed that there is no place on the intake to install the 1/2 NPT stock temp sender.

So I have a hole in each head and on on the intake for possible temp sender locaions and all 3 are 3/8 NPT. The only 1/2 NPT hole on the intake is for the heater hose outlet.

Is there a 3/8 NPT temp sender that works correctly with the factory temp gauge ??? Thanks.

[shifty]

you should be able to buy an adapter. i have several down in my garage that i got with my SunPro gauge kit - i think they sell a kit too....if nothing else, hit your local hardware store. they will have one.

[Longhorn Man]

Didn't some one on here use a sensor out of a volvo?

[Tx Firefighter]

I don't believe an adapter is a possibility in this case..

The sending unit is larger than the hole he needs to put it into.

I have run into this problem before and never found a good solution.

Usually, I use the threaded hole in the intake manifold by the thermosta outlet if there is one.

One time though, I wound up putting the sender in the thermostat outlet itself. I used an outlet that had a hole for a vacuum switch, which was 1/2 NPT threads. You can buy an outlet like this at any parts store. Ask for an 80's era 305 housing. You guage won't read correctly till the engine is warmed up enough that the thermostat opens though.

[70GMCer]

Now I know I will most likely get slammed here, but I took the drain cock out of the bottom of the radiator and put that size sensor in. Worked for me. I had to do that because I couldn't get the plug out of the side of the head on the engine. I have since replaced that engine and went back to to original location for the sensor. Keep in mine, that was for an after market gauge, but still worked good.

[Green Machine]

Please don't tell me I'm SOL ??? Damn, just when you think its going OK....

How could I find something that works, ohm meter and some hot and cold water ???

Have a pic of the intake here : http://67-72chevytrucks.com/vboard/s...d.php?t=196325

[GMCMAX]

Pull the manifold, drill and tap to 1/2"? Waste a set of gaskets, but it's at least on the floor and not in the truck.

[kwmech]

You can pick up a 3/8 sender from the parts store with the correct ohms, I have done it several times with an engine swap

[Tx Firefighter]

kwmech, try to get us an application or part number.

I've taken my multimeter to the parts store before and tested different ones, but never was able to find which one had the proper resistance value and the correct thread size.

[Fred T]

You can use an adapter, but you won't get a good reading. Drilling and tapping can be done with the manifold installed, grease the bit and tap to catch the shavings and use a magnet.

[Green Machine]

I'll bet someone has figured this out, any thoughts ????

[kwmech]

If I remember I'll get a part number tomorrow.

[EROC]

I've been thinking about just taking the regular 1/2 inch sensor, and turning it on a lathe and then tapping it to 3/8 inch. I don't know how much metal you can take off the sensor, but a 3/8 inch pipe die slides right past the smaller end of the sensor. There should be enough there that it would'nt damage the sensor. Let me see what I can come up with.

[Fred T]

FROC - If you have a bad sensor, cut it open and measure the thickness. I doubt if it will work, but you don't know until you try.

[Woody]

The info I have gleened from this BB before said to use a sensor from an early '70's Volvo (sorry no P/N ) and that with this sensor, 180 degrees will put the needle in the center of the gauge.

[Longhorn Man]

I thought I remembered volvo for this.

[EROC]

Alright, so I went to Advanced Auto and bought them all out of temperature sensors. I ground one down until all the threads were gone. This put it just about right to get it started in the die. I did'nt cut one open, but the threaded end is still wider than the probe end. I don't think it should hurt the sensor.

[pjmoreland]

Very nice! I'll bet there are a lot of people who would pay you for that modification, me included.

[Green Machine]

Eroc - that looks really nice, put me in line if you want to make a few more - looks like you bought three, price me one out shipped to 51334 - Thanks

[EROC]

If you guys are interested I can make a few and ship them out. To keep things legal I'll post them on the parts board. If you want one please reply there. How about $25 shipped.