Originally Posted by fourty6hotrod
I bought new Auto Meter guages and went to put the temp sensor bushing in and it won't screw into the head. The bushing is 3/8" for an electric guage. The engine came out of a 1955 Bel Air and from the research I did it came with a mechanical temp guage. I don't know if the mechanical bushing had different threads than the electric? I've went to the auto store and hardware stores looking at different bushings and nothing will fit. Hopefully someone can help me because I have no Idea what to do next ???
Thanks for any help,
I believe what you have is a head with a straight cut thread and your new bushing is a pipe thread (NPT) which is a tapered thread, they won't work together. One solution is to retap the head to the new bushing size.