C15 rocker box studs

[KernowPete]

Can anyone confirm the threads top and bottom of the C15 rocker box studs in the 40-121 head please?
Rupert ratio has them as 1/4" BSF whereas Draganfly have them as CEI. The thread for the stud above the exhaust port has gone thanks to an old repair that eliminated the dowel. I need to drill deeper into the material around the exhaust port and retap. I'll probably replace most of the studs too.

[KernowPete]

Well I need to get on so in absence of any reply I'm going to go with BSF-BSF for the 1/4" and BSF-CEI for the 5/16"

[Stevegayler]

If it's any help, my 1969 B44 rocker box studs are 1/4" BSF.

[Greenfield]

If your rocker box studs are 40-131, they should be 1/4CEIx2 1/4". The head studs are listed as 40-127 which are 5/16CEI/BSFx3".
Hope that helps

[KernowPete]

Thanks chaps. I've ordered what I've listed above. Hopefully that'll work out ok. This is my first foray into classic bike ownership and threads and tool sizes are baffling. Seems much like pounds, shillings and pence!