Went to install the water temperature sensor into the head and ran into unexpected thread size.
The head is from 1954 (November '53 casting date), 3835913 casting number.
When I received the project there was a kluge of parts plugging the hole were the temperature gauge capillary tube would plug into the engine.
I tested the original gauge by heating the sensor in a pan of water and it worked!
I purchased a new inexpensive gauge set to use for the initial start up of the engine and the threads on the new capillary and old capillary tubes are the same.
I pulled out the random parts that had been plugging the hole in the block where the sensor should go and the threads are not correct for the adaptors that came with the kit. (The old parts would not work for connecting the capillary tube. They were just used to plug the hole.)
From what I have read, it seems as though the block should be tapped for a 1/2" pipe thread, but it seems to be tapped with more of a fine thread. (My eyes are not very calibrated for identifying pipe threads.)
I found this problem after the local FLAPS have all closed, and, in reality, I may need to go to a shop where the folks know more about what they are looking at than what I have found at the FLAPS recently.
The threads on the old part that was threaded into the block appear to be 24 per inch.
Is there a specific adapter that I should be looking for, or just hope to get lucky and find a bushing that works?
Nick 1940 KC Model 1/2 Ton Pickup Project (with '37-'39 Bed and what we think is a '42-'46 Frame) Taos, New Mexico
Perhaps I should call them and see if they can tell me the thread pitch of what they sell. In the photos I have seen the pitch looks too coarse. I guess I will have to wait until Monday to speak with anyone.
Nick 1940 KC Model 1/2 Ton Pickup Project (with '37-'39 Bed and what we think is a '42-'46 Frame) Taos, New Mexico
The early cylinder heads did not use an adapter. The thread on the capillary tube nut should fit the head without any adapter needed. The 1/2" NPT sensor thread came later, and needed the adapter. There should be something like a 5/8" fine thread in the head, and a flat seat area for the capillary tube bulb to seal against. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Jerry, It looks like your recollection is correct; the threads in the head seem to be 5/8x24. I don't have anything to test them with at the moment. I have not found what appears to be the correct adaptor out there from the vendors yet.
I have attached a few marked up photos.
One of the photos shows the temperature sensor bulb that is attached to the gauge in the (original?) dash. The threaded adaptor on that one is significantly too large. Any idea of what engine might have been in this truck that would have used that?
Nick 1940 KC Model 1/2 Ton Pickup Project (with '37-'39 Bed and what we think is a '42-'46 Frame) Taos, New Mexico
You need to separate the two pieces of the sensor bulb in the last photo. Then the square head fitting will thread directly into the head. The sensor bulb has a shoulder that bottoms out in the counterbore below the threads in the head. That adaptor appears to have a 1/2" NPT male thread to fit the later model heads. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
