todd j

Here's a picture of back of gauge. Sorry it doesn't show much detail. Putting a tape measure across the opening shows 3/8" Thanks for the help

I have a restored instrument cluster from a 1933 Plymouth that I am going to use in the build of my 1930 Model A highboy roadster. I am having trouble with the correct fitting for the oil pressure gauge. It is female threads and appears to be 1/8" NPT, but that fitting will not thread in. It will go in maybe 1/2 of a thread and then seems to bind. Threads are clean on both fitting and gauge. Is this a different size other than 1/8" NPT? Thanks for your reply