The octane ratings of fuel in Australia are: Unleaded 92 or 96, leaded 96.
MGs delivered to Australia all had the high compression engine for which 96
octane is needed. Most people get hardened valve seats fitted when
overhauling the heads as a hedge against leaded fuel becoming unavailable.
60% of cars in Australia require leader fuel and an octane rating of about
96. The lead content has been reduced to 0.1 grams per litre which is
sufficient for valve lubrication and offers very little pollution. By
machining a small amount off the tops of a particular type of piston it is
also possible to get the compression ratio down to about 8.6:1 and so
suitable for the cheaper standard unleaded fuel.
The MGB GT V8 is not a problem since it is 8.2:1. the MGA was 8.3:1, except
to the last of the four cylinder models, which was 9:1
Regards,
Graham
Graham McCann Rivett, ACT. Australia
gmccann@pcug.org.au
06 2889055
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