Back to the extra block studs

[Zetomagneto]

Charles - I've no experience with supercharged engines , however I have always 
converted both crankcase / block and block / head studs from BSF to equivalent UNF sizes.
5/16" BSF = 22 tpi , UNF = 24 tpi .
Seems to work on all my Ulster engines although my ex Reg Nice car has stated to leak oil
from the front of the block - I know this is BSF !
Just a thought .

Geoff, why would you do that, a courser thread into aluminium gives a better fixing, your going finer, and damaging Crankcases at the same time.
I appreciate a finer thread will give a higher clamping force, but lack of clamping force is not the problem, the problem is stopping the studs pulling out of the Crankcase.
You refer to "all my Ulster engines" it would be a shame if you have damaged genuine Ulster Crankcases in this way.
If you have done this to all your engines, how do you know the tried and tested over 80 years BSF doesn't work? 
If you want higher clamping force, or less likely to come undone you could make some studs BSF at one end, cycle thread at other end, but unnecessary in my opinion.
Can you please enlighten me as I am always willing to listen to new ideas

Does anyone else have view on secure crankcase studs, I know of at least one successful racer who loctites his standard suds into the crankcase and immediately preloads them so that in the threads in tension are in metal to metal contact,i.e. The tension is not through the loctite film.

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Well, I'd go for the longest stud possible. More stretch length is good.

What I was pondering is described in my very poor sketch below.

The idea is:
1/ Tap a 5/16 thread into the crankcase/rear cam bearing
2/ Insert and loctite a 5/16 normal length stud
3/ Turn up a 1.75" length of 5/8 AF hex bar threaded 5/16 female in both ends to be a joiner.
4/ Torque the hex "joiner" onto the stud
5/ Attach the bracket to the head and insert the long stud into the hex joiner 
6/ Torque the long stud down to 5ftlb less than the hex joiner

The raionale is to provide a neat, repeatable set up where the crankcase doesn't just have a stud tapped into it with no clamping helping to support the metal around the stud.




Criticism and suggestions welcomed about everything except my draughtmanship!

Charles

Charles, this looks like a good idea, tried and tested.Using this method helps to keep the top of the block intact with the bottom, whereas if you attach brackets to the base of the block there is still a possibility of the block breaking like your last one.