Radiator cap (quail) grub screw size

bavArian

Senior Member
Hello everyone,


haven't found it with the search, so I'll just ask:
While removing the quail from the radiator I lost the grub screw that locks the rad. cap in place. Unfortunately I only realised I'd lost it when I mounted it again, so the screw is god knows where.

I'm measuring ~3.65 mm or ~0.142 inch ID at the thread of the quail. So I'm guessing it's a #8 - 32 UNC, is that right?
As we only have metric screws in our DIY-shops I have to order one online, so I'd like to get it right the first time.


Thanks,


Daniel
 
I believe it is a #8-32 x 1/8" set screw. It's poorly documented and it's possible that different vendors used different sizes.
 
Why not just re tap the threads to metric and use a metric set screw. Who’s going to know? I won’t tell anyone. ; )
 
Why not just re tap the threads to metric and use a metric set screw. Who’s going to know? I won’t tell anyone. ; )




That would be a good solution, but I think I want to save that for when the thread is damaged. With how thin the cap is in that area I believe that's bound to happen in the future. :p
Guess I'll just try the UNC and if it is a different thread I'll re-tap it.
 
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