>Date: Mon, 23 Nov 1998 07:38:08 -0700
>From: "Andrew B. Lundgren" <lundgren@iname.com>
>Subject: Re: Lead Additives
>
>>Do we need to use lead additives in our petrol?
>>If I read my drivers manual correct it stated to use leaded fuel.
>>Any suggestions?
>
>Some say they are a waste of time and just to rebuild your head now.
This is a big issue over here where Lead is only now being phased
out. Keep in mind what the lead is for:
1.) raising the octane rating of the fuel, a task admiraby performed
by other compounds.
2.) coating the valves and seats to prevent recession, ie., wearing
away.
As to the second, once the valves are coated with lead (say from a
decade of use on leaded fuel) they are coated. End of story until
you need a valve job anyway or damage your engine with pinging.
Say the built up lead happens to wear away. Portions of the now soft
seat and valve face are micro-heated by the combustion airflow, and
tend to stick together. With each opening of the valve an additional
microscopic bit of metal is torn away. End result: You need a valve
job. Now, in my book doing a 'no-lead conversion' valve job in order
to prevent the possibility that I might need a valve job is , well,
premature. If you need head re-build, put in hardened 'no-lead'
parts. Otherwise don't worry, because the only thing you can damage
by not doing head rebuild is the parts that you would renew in a
head re-build anyway.
I'm no expert, this is all second-hand knowledge. I've been running
my 72 B-GT on no-lead since I purchased it two years ago.
Douglas McKinnie (currently in Guildford, UK)
1972 MGB-GT (currently in Cleveland Ohio)
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