Paul Amaranth asks:
>Among other cars, I have a '73 Triumph Stag with the engine apart. This
>car ran on leaded fuel, so I'm wondering what, if anything, I should do
>about the exhaust valves and seats. The reason there's some confusion,
>is that they used the same part numbers for the exhaust valves and
>seats on the TR7 engine which did use unleaded fuel. This brings up a
>couple of questions:
> 1) Are these really the identical parts? BL didn't change the
> physical composition and keep the same part number, did they?
> If they are the same, does that mean they put hardened seats on the
> Stag, or unhardened seats on the TR7?
> 2) How do they hold up in the '7? Anyone see any significant errosion?
>I'd like to avoid replacing them, if possible. Anyone have any info?
I'd bet that the seats are totally acceptable for unleaded use. As both
cylinder heads are aluminum, they had to have valve seat inserts. Those
inserts are likely all capable of running on unleaded fuel as I really
doubt that there was any change to the composition of the material used
for the valve seat inserts.
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Bill Sohl (K2UNK) BELLCORE (Bell Communications Research, Inc.)
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