John Kippings advice on Unleaded fuel:
"If you want to convert your Triumph,just put some unleaded in it" he
says,"just do it"
During the 1920's the fuel industry discovered that putting lead in fuel
increases it's efficiency or 'octane'. The lead laid down a tough deposit on
the exhaust valve seat,so that the motor industry could save money by making
seats from softer steel.
So if your car is post-1920,you must be careful,you can use unleaded but just
not all the time.If you do,the two possible consequences are that the engine
will start to pink due to reduced octane.the other that your unprotected valve
seats will be ruined in a very short time,(3000-5000 miles),and you will have
to buy a new cylinder head.
The amount of lead required to lay down a deposit is very small.Peter Sloan of
the Petrol Industry Association,says 0.05 grams/litre is enough. The minimum
amount of lead legally required in British 4 star is now 0.05g/litre,the
maximum 0.15g/litre.
But you are unlikely to find less than 0.14g/litre,because adding the maximum
means petrol is cheaper to make.So every time you fill up with British 4
star,you give your engine 3 times the lead it needs for protective deposit
purposes.
These gummy halides & oxides last for another 3 or 4 tankfuls.
The Kippings go on to say thatThe deposits on the exhaust valves of a Four
or Six Cylinder Triumph engine with 50-60,000 miles are sufficiently deep &
hard to allow you to use unleaded with impunity.However,they suggest you use
unleaded for 3 of every 4 tankfuls,just in case.
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The full version of that article by Eric Bailey first appeared in the Weekend
Telegraph.
Since that article was written,I believe that the amount of lead in 'leaded'
British Petrol/Gas has continued to fall,also 'unleaded' British Petrol/Gas
apparently contains a very small amount of lead,thus the two versions are
becoming increasingly closer together...and of course after 1st January 2000
that'll be it.
Leon
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