Y block temp sending units

[junkyardjeff]

I picked up a 61 292 for my 55 and want to use the original temp gauge but I think the 57 and up heads are made for a smaller temp sending unit,is there a sending unit made that will work with my gauge that will fit the later heads or will I have to drill out the head.

 

[Daves55Sedan]

Actually, the heads have a threaded bushing pressed into the bore in the head. People who want to convert their newer heads to the older style sending unit can buy the bushing with the larger threads which was used until the end of the '56 model year. The '57 and later threads had a bushing with threads for the smaller sending unit. These bushings were available from most of the premium repro parts suppliers last time I checked.
In order to remove the bushing that has the smaller threads in the newer head, it is best to heat up the head around the bushing with a torch and use a puller having that smaller pipe thread to pull it out. Heat is also needed to insert the new bushing into the head. It is a pressed fit so it don't leak.

 

[dmsfrr]

Only a '55 (or '54?) Temp sensor has the right electrical spec's to pair with a '55 Temp gauge.

The Temp sensor bushing is made of brass or something relatively soft.
The smaller style bushing in a '57+ head is easy to drill out (9/16) and tap to the larger size for an older sensor, 3/8 NPT.

 

[paul2748]

You don't need heat to either remove or install the bushing. I have done both operations. There is a removal tool made for removal (CASCO has it, I assume others have it). To install, all you do is carefully hammer it in straight, like installing a rear axle seal. I little sealant should be used when installing.