Hi Dick, good question about the block deck when you put Arduns on a
flathead. The short answer is you don't have any problems about it and
no welding is necessary.
A factory-relieved (Ford made some, and by the way my dad's '51 Hudson
Hornet also was factory-relieved, as I observed when it got a new gasket
at high mileage) or other relieved block cannot be used with Ardun
heads.
In the early days people sometimes welded in the valve relief area on
the left bank of the flathead block as the flat surface near the bores
in sometimes a little less than 1/8" wide. It is really not necessary
to do that however and the practice today is to skim the deck down on
that side (for some reason it usually seems to be 'higher' on the left
side anyway, which if you don't skim it gives you lower compression on
that side) until you get 1/8" of sealing surface from all the valve
reliefs to whatever bore size you are using.
The original intake ports are ignored. The original exhaust ports on
the block have to be sealed with plates and gaskets, they fill up with
oil from what flies around in the engine, which is of no consequence if
it doesn't leak, but makes a mess when you eventually open it up. I
find that NAPA 1/16" rubberized cork gasket material seals the exhaust
port plates indefinitely.
There are three schools of thought for Ardun head gaskets. 1. one
piece dead soft copper about .040" thick, with or without o-rings around
the bores to 'key' it. 2. copper o-rings around the bores with
separate paper gaskets maybe .005" thicker to seal the water holes. 3.
traditional composite gaskets with metal around the bores and maybe the
water holes. Each system has its advocates.
I will say getting a permanent 100% seal at the cylinder head joint is a
basic issue with the Ardun, but it is done all the time, and all engines
have the same basic issue, which still today occasionally causes
trouble.
As with any other cylinder head joint, the mating surfaces of the block
and head have to be reasonably flat and free from deep scratches.
Various operators torque their Ardun head studs 35 to 60 ft. lbs, but I
like the low end for mine because the thick aluminum casting must expand
a lot when it heats, increasing the torque, and I have this theory,
learned working on aluminum motorcycle engines all my life, that with
aluminum structures you want the minimum torque that will seal reliably
under all working conditions, any more just distorts the parts. Cheers,
ArdunBill
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