Bulb Horn Thread Specification

[Preacher]

Does anyone know for certain the correct, original thread specification for the threaded brass connections?

 

[tmodelman]

Well, tall order, as many kinds of bulb horns have been made., and different dia. tubing, and different sizes of bulbs.

But when restoring my original Rubes twist, to put on a '09 runabout, bought repro tubing and mount, it the thread fit up was just right.

Got replacement parts (mount and reed) from Restoration Supply, and their catalog says the horn parts threads are 5/8 x 32.

 

[Preacher]

Thank you! I had not found that bit of needed info. I took some of my pieces into our inspection department and the repo parts were (.010 oversize) 5/8 x 32tpi .... or 27tpi, depending on which part they looked at. one of the thread profiles looked more like ocean waves! no wonder I couldn't get it to fit! anyway thanks for confirming what we did come up with today on some of the original threads... 5/8 x 32.