68 Lightning rocker cover studs

[teamjohn]

Can anyone tell me the thread of my 68 Lightning rocker cover please

John

[A10 JWO]

1/4 CE126 BSF according to spares  book.

[chaz]

oh dear, here we go again...1/4BSF are not the same as 1/4BSC, both 26tpi but different thread forms. 55 against 60 degrees.

[ChrisG]

Yep! 1/4" BSF thread goes in the head and cycle thread for the nuts. I've always wondered why they do this. Anyone know why the different thread profile? (They are both 26TPI)

[chaz]

from an engineering point of view, we used BSF as easier to get fastners than BSC. ( I cleared the stores of fastners and BSC tooling)
as for profile, the 55degrees gives slightly more material than the 60.
threads in ally castings use a coarser thread to avoid the stripping of threads when tightening, in steel such as nuts, there is more strength in the material so not as much of a problem

[Mike Farmer]

 

As you only need to tighten them enuf to make the top oil tight I use !/4 allen screws. Not correct??? you're right. But as a lot of us are using pattern parts, it's not a problem to me.

Mike