Ken Owen's wrote:
Also, since the exhaust valves are smaller, would this not be a reason to use
the early model head
(without machining the later head to accept the larger valves). I do realize
the valve springs are
different. I am wondering if the perforance gains between early and late model
lies in the head or
really is in the longer intake manifold. Looking for all the performance gains
I can get, so, if
there is a real reason to overhaul the extra head I will do so.
Ken - a great deal of research work was done about 8 years ago in the UK by a
guy called Chris Witor
who is something of Triumph guru. Chris wrote a very interesting and
informative article in one of
the UK club magazines on cylinder head flow properties. The 219015 and 016
heads (the later ones)
are better overall even though the later head has a smaller exhaust valve
diameter. In tests using a
variety of different heads, Chris' report showed conclusively that in terms of
optimum gas flow, an
015 or 016 head with the smaller exhaust valve dia was by far the best.
Jonmac
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