----- Original Message -----
From: "Jeanne Lacourse" <cckw@mediaone.net>
To: "Military Vehicles Mailing List" <mil-veh@mil-veh.org>
Sent: Sunday, November 12, 2000 2:38 PM
Subject: Re: [MV] Diesel
> I should have corrected my statement: I know of the lead/unleaded
problems.
> I do not believe that kero is a substitute. I was looking for an answer
like
> it makes it burn cooler etc. I am well aware of the valve recession
problem.
>
Certainly kerosene (paraffin) will take the octane rating and volatility
down a bit, it definitely is not a lead substitute nor does it do any
exhaust valve seat lubrication.
Looking at old and pre-war manuals for many types of vehicles it would seem
seat recession was an accepted fact, valve grinds at around 5,000 miles
intervals were the norm.
> Is this possibly related to the problem when they switched from 3 grades
to
> 2 grades of gasoline in WW2? There were reports of some engines not being
> able to take the higher (80 as I recall) octane gasoline.
>
This can get confusing, whilst leaded fuels being introduced large-scale
during WWII as mostly a quick-fix for dreadful fuel quality as an instant
octane boost saved seat recession, the attendant problems of stem corrosion
and failure before the wide spread use of nimonic steel alloys became
apparent. Ford CMP manuals certainly devote a page to the "different"
appearance of the engine internals after the use of leaded fuels, often the
older term "ethylised" is used to mean leaded as the additive is tetra ethyl
lead.
The 80 octane fuel you refer to would be the regular and awful pool dross
with a good splosh of TEL, likely its the corrosion aspect the engines
couldn't handle, not the octane rating as such.
At the time remember these nimonic alloy steels were the preserve of
cutting-edge aero engines not found in army chuggers, the Battle of Britain
was fought with Merlins running on 80 octane AVGAS !
Richard
Southampton - England
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