Repair and modification discussion
1 post • Page 1 of 1
- Posts: 64
- Joined: Fri Aug 20, 2004 3:25 pm
- Location: St. Louis Park, MN
Does anyone know what size thread is used for the old short action Conn pistons? New stems I’ve bought for my 25J are 1.625” long and the old ones are 1.730” long. I made a shim tube for under the valve button to get the length correct for proper porting, but I’d like to make new stems that are the proper length. The button thread looks to be 12-32, but the male threads for the valve appear to be 15/64-32, which seems really odd. M6-0.8 is close but slightly larger and a rare size to find. The major diameter of the threads is 0.230” or 5.85mm. I know I can single point the threads and make them fit, but I’d like to know the theoretical correct size so I can get set up and make a few and know they should fit any horn in the future that still has the original threads in the valve.