Valve work on testa fissa

[Taiju Kobayashi <kobao@xxxxxxxxxxxxxx>]

JHertzman@domain.elided wrote:
>The great merit of the fixed-head design was, of course, a definitive end to
>head-gasket problems. It also generally allowed larger valves and better
>coolant circulation passages, but made valve seat work a bit more difficult,
>particularly on the smaller bores, like the 54mm of the Tipo 512. (Perhaps
>their mechanics have small hands?)

Once I had a talk with a mechanic who recently restored a TipoB(P3) engine
in Japan, and he said he had to make a special tool for valve work. He made
a tool that holds valve stem for seat-rubbing. This method doesn't require
"small hands" with valve rubber.
One mystery is how did they inserted the valve seat deep into the combustion
chamber. Period aero engine engineer may have the answer. Anyone here??

Tipo B engine has a straight cut valve gear train that needs proper backrush
kept. But actually it has no adjustable shim in the train itself. Instead, the
mechanic prepared several copper gaskets between crankcase and cylinder
block with varied thickness, and found the best set by
assembling/disassembling.
No question, the copper gaskets are the largest shims I've ever seen;-)

Just for your info,

Taiju Kobayashi
'66 GTV "Corsa"
'91 75TS
Tipo B in the bookshelf.

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