Bert.Otten@nni.nl (with the funky attribution scheme) writes:
>
> >I recall a thread about using unleaded gasoline in an MGB engine
> >without an 'unleaded head'. There was a chance that your valves
> >would get burnt in the end, say after 100,000 miles or so, but
> >possibly not before your engine needed a rebuilt anyway.
It's not that your valves would get "burnt", which, as I understand it,
refers mainly to exhaust valves, which must withstand very high
temperatures. It's valve seat recession which is the "problem" with
unleaded gas. When your valve seats recede, your valve clearances
approach zero. When your valve clearances go negative, the valve no
longer contacts the seat, which is a Very Bad Thing. For exhaust
valves, this promotes burning, but has nothing to do with unleaded gas,
since only the intake valves get the "benefit" of lead/lead-substitute
lubrication. I haven't much clue as to what negative valve clearances
mean to an intake valve, but it sure as hell won't make your engine run
better.
> >(Retoric
> >question: Is this really true? Why am I putting expensive leaded
> >gasoline in my MGB?)
It's pretty much a Holy War type of thing. Some people swear by the
inserts, others claim there's no need. And one or two people will tell
your stories about how the insert separated from the head, clanged
around inside the cylinder, and generally acted antisocially with
precision-ground surfaces.
ObPedantic: Your question(s) really wasn't "rhetorical", since, from the
context, an answer was both expected and readily provided.
--
Todd "Not that I know what I'm speaking of" Mullins
Todd.Mullins@nrlssc.navy.mil On the lovely Mississippi (USA) Coast
'74 MGB Tourer
"I could go at any time..."
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