>I was puzzled about three heads I have and what they are. Here's what I
>found:
>
>#1 has a 1-5/8" port (at the face) with what appears to be a little
>machining to get that diameter,
(That would be the ball mill made at the head to intake manifold face to
assure a good fit between the head and intake manifold given
miscellaneous slop factors)
> no flat on top, and no water neck
>chamfer. Obviously a TR3-early TR4 head.
I think your #1 head one as a TR3-3A head for 83mm pistons. This is the
first high port head casting.
There was a later head with a camphored lower thermostat housing that was
for use with 83mm pistons. I'm guessing this later head started
production in late 60 or later. It may have even been a factory
replacement head made after 83mm piston engines were out of production,
and intended for the factory replacement parts market. This head exists
but is undocumented.
[NOTE: The camphor on the edges of the combustion chamber was added for
heads intended to go with 86mm pistons. No camphor is present at the
base of the combustion chambers if the head was intended to go with the
83mm pistons.]
>
>#2 is most interesting to me. It has 1-9/16" ports at the manifold face,
>a chamfer on the bottom of the water inlet, but no flat on top. I'm
>deducing that this head was made after they stopped putting the manifold
>face chamfer in the heads but prior to putting the flat on top (where
>the number is stamped).
>From your description, I believe that this is the second high port intake
manifold casting, intended for use with 83mm pistons. If you are running
83mm pistons or want the higher compression you get with 86/87mm pistons
and no combustion chamber camphor I believe this is your head of choice.
It has more metal between the bottom of the head and the water jacket
than the earlier casting. You can safely mill it for higher compression
with 83mm pistons.
To make things even more interesting, the factory made 86mm pistons an
orderable option starting sometime in 1957 (I have a photocopy of an
Standard-Triumph parts list addendum that shows the part numbers for the
86mm pistons). So there should be early heads of some kind with a
camphor on the edge of the combustion chambers.
>#3 has 1-9/16" ports at the manifold face, a chamfer on the bottom of
>the water inlet, and a flat on top where numbers are stamped. Obviously
>a later TR4 head that we call the 1-1/2" head, reputed to be the best
>performer all round.
You did not say it but this head probably has a camphor at the edge of
the combustion chamber. I'm guessing from your description that this is
the early 86mm piston compatible head that was used on the TR3B and TR4s.
My guess, without actually seeing them, is that none of the three heads
is the late TR4A head.
TeriAnn Wakeman Marigold Ltd.
Santa Cruz, California Web design, site updating, testing
webmaster@overlander.net search engine optimization, graphics
and more
http://www.overlander.net/Marigold/index.html
|