These high quality exhaust studs are produced from corrosion resistant 321 stainless steel in 5/16 x 18 standard thread size (oversize available soon) and are a direct replacement for the Lycoming part number 31C12 stud.
These studs stop stud corrosion and rust out problems, stop expensive cylinder repair costs cause by broken studs, allow easy removal of exhaust systems for gasket replacement or inspection, and feature a safety wire hole to insure security of the exhaust stack on each cylinder. FAA approved for all Lycoming engines from 0-235 thru 0-540.
Work great I use to change studs anytime I removed stacks. But with these guys you can almost reuse. Only issue is that they are kinda on the short side. Not gonna be able to use the hole for safety wire as the stud just clears the end of nut
Replaced rusted studs on my back cylinders exhaust on 0-320, did the job, looking forward to not having rusted studs on next exhaust gasket replacement.
The 08-06780 has 5/16"-18 threads on both sides. Our part number 08-07282 has 5/16"-18 x 5/16"-24 threads.