I would like to cap off my master cylinder lines after I remove the master cylinder to rebuild it. Does anyone make 1/2-20 & 9/16-20 brake line caps?

Slide the tube nuts back and put some 3/16" silicon caps on the tubing.

If that won't work for you here is a good place to start:

https://www.summitracing.com/search?Sort...Plug%20Fittings

The 9/16-20 might be tough to find being Chrysler specific.

i make my own caps by using junk yard lines. just cut the line past where it comes out of the master nuts, then braze the line remnant/nut together. not sure however, if you have access to yard parts. weatherhead fittings, at one time, had adapters that went from the 1/2 & 9/16-20 thread to regular female 3/16" brake line. then all that was required was a pair of male 3/16" brake line plugs to make a cap. edelman also made these adapters. parts stores always had a couple of boxes of these [and other odd ball brake line adapters] behind the counter to help out with emergency repairs.

I just looked at 4 different brass fitting supplier catalogs and it appears to not be a standard part.

Closest I have found are unions and plugs in 1/2-20 but the 9/16-20 Nuts are not cataloged. I see 9/16-18 in both 3/16 and 1/4 tube steel nuts but no unions.

I did just find an adapter from 3/16 tube 9/16-20 male to 3/16 tube 3/8-24 female.

Fairview fittings

WH-7910 Male Thread 3/16 (9/16-20) to female inverted 3/16 (3/8-24) (I'm pretty sure this is of no help)

Red