Interesting, tried to take out carb studs to transfer to new barrel and they are slightly different.
Would not fit.
They seem to be Allen key slotted too, aids better removal.
Not 1940's these I think.



Paul Crisp

The correct thread size for those studs is 5/16" BSCycle (26tpi) I'm quite sure you won't get those with an Allen key end. It looks like someone has used a metric or different imperial stud. I would guess that they have been Helicoiled with the new thread Ron

email (option): ronpier@talk21.com