Cool/Heat: Temp Sender Tap Size

[345 DeSoto]

I have an NOS water temp sender PN 153976. It appears to be 13/16", straight, no taper diameter. What would the drill/tap size be for this? I'm thinking a 1/2 13 NC tap...is this right?

[StudeRich]

It SHOULD be Pipe Thread, Not NC.

[JoeHall]

The older early type is 1/2" pipe thread, and the later type is 1/4" pipe thread.

[bensherb]

Interesting; the one I removed from my '62 (V8) was 3/8" pipe, it wouldn't come out of the mounting plate. I have a second plate with one in it that will not come out either and it is 3/8" pipe too. I made a new thicker (aluminum, O-ringed) plate and used a new 1/8" pipe sender to replace the original sender and plate.

It sounds like what you have is likely 1/2" pipe;

1/2" NPT pipe has an OD of .840" and 14 TPI (threads per inch) drill 23/32" (.7188")
3/8" NPT pipe is .675" OD and 18 TPI, drill 37/64" (.5781")
1/4" NPT pipe is .540 OD and 18 TPI, drill 7/16" (.4375")
1/8" NPT pipe is .405"OD and 27 TPI, drill size "R" (.339")

When threading a hole for a NPT , tap only partially through then check the mating pipe's fit. You may want to check the fit several times when tapping. If you tap too far/deep the pipe will be too small to fit the tapped hole properly.

[345 DeSoto]

Can any generic 12V temp sender be used, or does it need to be Studebaker specific? I'd like to use a smaller 1/4 or 1/8 NPT sender...

[bensherb]

Can any generic 12V temp sender be used, or does it need to be Studebaker specific? I'd like to use a smaller 1/4 or 1/8 NPT sender...

A generic sender would be fine for a gauge if it's of the correct resistance range. I don't know what gauges you might be using or what that value is for any of them off hand, but I know the Stewart Warner gauges that were stock in my GT are the same as current aftermarket Stewart Warner gauges. I currently have Intelitronix digital gauges in it, the sender for the temp gauge is 1/8"NPT. I tried one as a lark, and liked it so eventually swapped them all; they're super easy to read at the slightest glance even with my poor eyesight. Here's a pic from before I swapped the speedo and tach, forgive the bad photography, cheap camera. They don't actually glare like that.

[StudeRich]

Forget the Digital Gauges! I am looking at the Interesting Tranny Shift Dial, looks like:
Park..... R.. N.. OD.. D.. 2.. 1 !!!

Obviously for one of those THM thingies!

[bensherb]

Forget the Digital Gauges! I am looking at the Interesting Tranny Shift Dial, looks like:
Park..... R.. N.. OD.. D.. 2.. 1 !!!

Obviously for one of those THM thingies!

I don't know what a THM is but when the original 3 spd OD decided the eat itself I chose to adapt a GM 4L60 AOD instead of rebuilding it (even though I have the parts and two spare transmissions). I was planning to go to a hydraulic clutch before the 3spd came apart, due to bad knees, but chose the automatic trans instead. The steering column is a GM tilt unit from a '69 pickup with a slightly modified shifter gate and a modified aftermarket indicator.

[Bo Markham]

THM = Turbo Hydro-Matic, as in GM Transmission, perhaps........... Nice set up.

Bo

[345 DeSoto]

GM Turbohydramatic….

[altair]

Interesting; the one I removed from my '62 (V8) was 3/8" pipe, it wouldn't come out of the mounting plate. I have a second plate with one in it that will not come out either and it is 3/8" pipe too. I made a new thicker (aluminum, O-ringed) plate and used a new 1/8" pipe sender to replace the original sender and plate.

It sounds like what you have is likely 1/2" pipe;

1/2" NPT pipe has an OD of .840" and 14 TPI (threads per inch) drill 23/32" (.7188")
3/8" NPT pipe is .675" OD and 18 TPI, drill 37/64" (.5781")
1/4" NPT pipe is .540 OD and 18 TPI, drill 7/16" (.4375")
1/8" NPT pipe is .405"OD and 27 TPI, drill size "R" (.339")

When threading a hole for a NPT , tap only partially through then check the mating pipe's fit. You may want to check the fit several times when tapping. If you tap too far/deep the pipe will be too small to fit the tapped hole properly.

I don't think it matters a fat lot but my chart says drill 45/64 this may be a tad tighter fit (by a 64th).
I am drilling out a 1/4 pipe and re-tapping to 1/2 pipe. My 63 engine was originally 12 volts and I have converted it to 6 volts, therefore the 12 volt sender requires to be modified to a 6 volt unit with the 1/2 pipe thread.