Water manifolds

[Nick Turley]

What is the best way to seal the bolt head or stud nut where it meets the cast aluminium manifolds (Water outlet & inlet branch)?
The parts list says that a "set screw" (BC20/BC21/BC22 ) is used without any under head washer (neither flat nor spring).

As a point of order!! I understood that a set screw was fully threaded to under the head, and a bolt had a plain shank.
The Parts book illustrations clearly show what I would describe as "sets" as "bolts", and elsewhere in the parts list fully threaded fasteners are called bolts!
Did the terminology change, or have I been labouring under a misapprehension for years? Of course, to confuse the issue, short "bolts" are often threaded right up to the head to give sufficient thread engagement!
Is there anywhere published a list of fasteners used on Austin Sevens by diameter/thread/head style? 
I wonder if/when Austin ever "commonised" the part numbers across the range of vehicles...Austin 12's etc must have used the same etc fasteners as Sevens.

I find Dowty washers are the best solution.
Hope you find that helpful.