Re: pre and post improved cooling heads

["Allan Weidenheimer" <allanw@domain.elided>]

>why did IH leave in the openings for the old water jacket inputs that now 
>require freeze plugs?
Mike:
I don't know about the swap you proposed, but consider this:
Those heads are cast iron.  To form them the way they are, SAND is
packed around a mould, and the entire area that is a water passage had
sand in it when the molten iron was poured into the mould.  Once solid,
the sand was removed from the outside, and that sand in the water
passage had to be washed out.  It could be those holes (which are in most
other manufacturer's heads too) are there to provide a sand bridge to 
support the sand until the iron is poured around it, and to make getting
that
sand out easier.

Just my theory, I did see a movie that showed a block being cast once
though.
Also note, freeze plugs is a misnomer; they provide no protection if your
block 
freezes.  I think 'Core' plug is a better term.

Allan Weidenheimer
72 1210 Pickup, Electronics Engineer, Lego Owner (still have'em packed away)