> Did the factory make any changes in the materials used in the head for
> the RBB's? The RBB's that came to the US would never have run leaded
> fuel, and if the materials are the same, and lack of lead was
> a problem,
> we'd have seen it by now.
The federal spec. heads for unleaded use had induction hardened seats that
required a higher concentration of tin in the casting alloy. BL decided to go
this way supposedly after nixing hardened seats. There were a number of other
changes to the engine so it would survive with the catalytic converter such as
going back to smaller valves which allowed larger cooling passages. Rings were
changed to reduce the amount of oil being burnt, and the head gaskets were
upgraded. This info from the "BMC and Leyland B-series Engine Data" book by
Lindsay Porter. According to the reference, hardening the valve seats alone
cost 173,000 pounds.
Kelvin.
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