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Full story: <a class="moz-txt-link-freetext" href="https://en.wikipedia.org/wiki/Thomas_Midgley_Jr">https://en.wikipedia.org/wiki/Thomas_Midgley_Jr</a>. and
<a class="moz-txt-link-freetext" href="https://en.wikipedia.org/wiki/Tetraethyllead">https://en.wikipedia.org/wiki/Tetraethyllead</a><br>
<br>
In a book on aircraft maintenance I have buried in a box somewhere
there was more: Midgely, at Sloan-Kettering--inventors of the
electric starter BTW--tested over 4,000 compounds and found
tetraethyl lead (TEL) to be most effective at preventing detonation,
allowing higher octane fuel hence more powerful, higher-compression
engines (and, presumably, it was suitably cheap--this is the first
I've heard of this conspiracy theory, though it's plausible).
Allegedly a serendipitous side effect, TEL causes thin elemental
lead deposits to build on exhaust valve seats which offered
protection--a sort of cushion--from erosion of the seat onto the
valve backside of the valve (and does somewhat cool the valve). I
have never come across anything that attributes the need for TEL to
'poorly designed' ignition systems (I'm open to evidence). ICE
aircraft engines have used magnetos almost from Day 1--SS systems
have been tried but generally found lacking--and most engines have
two (they'll run on one, but produce more power and run smoother on
both). A properly tuned magneto will throw a massive spark and they
are quite (necessarily) reliable (dirt track cars, for one, still
use them, requiring push starts). They're usually timed at 20-25deg
BTDC and have no provision for advance/retard. Modern small engines,
from chainsaws and lawnmowers to quads, use a form of magneto,
driven and timed off the crankshaft. I sometimes tell people piston
aircraft engines are glorified lawnmower engines. <br>
<br>
Gasoline for ICE aircraft--'avgas'--still contains a significant
amount of TEL; enough that, in some lower-compression engines
elemental lead can form on spark plug electrodes causing misfiring,
which can be burned off with a short ground run at high RPM at max
lean condition. There is considerable research ongoing to create a
suitable replacement for TEL in ICE aircraft engines and, IIRC,
there is a mandate from the FAA to remove it (someday). The major
engine manufacturers, Continental and Lycoming, are quite resistant
as they get enough lawsuits already. Since ICE aircraft cylinder
heads are aluminium they have always required inserts. <br>
<br>
As for conspiracies, Henry Ford initially wanted to use ethanol--he
could refine his own, like he tried to make his own rubber in S.
America--as fuel for his cars, but someone--I believe it was
Rockefeller--'convinced' him to use gasoline which, at the time, was
a nuisance byproduct of the refining process of kerosene for lamps.
See also: How Ford and Firestone conspired to 'kill' public
transportation in US cities. <br>
<br>
<br>
<br>
<br>
<div class="moz-cite-prefix">On 8/25/2024 10:23 AM, Hank Leach via
Healeys wrote:<br>
</div>
<blockquote type="cite"
cite="mid:dbc8b692-2ca9-f6cf-dae7-e01b7e8b40c3@charter.net">
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<div>I do not recommend that you do hardened seats. Chance of
damage to the head is high and then you will be stuck with
Aluminum.</div>
<div>There is no need to change the seats just because we lost
lead in fuel or that octane is reduced. If you drove the car
daily and put on mega miles a year this might be a consideration
but with today's conditions that probably is not going to
happen. The seats will last forever.</div>
<div>Lead to reduce knock was only needed in the early 1900's when
ignition equipment was poorly designed. The entire lead fiasco
was a ruse by the Ethyl industry to sell fuel...it was never
needed and finally banned in all but 6 countries.</div>
<div>The "additional" advantage of cooling the valves was not much
of a benefit and lead substitutes today are just alcohol and not
really effective. Exhaust valves run at 1800 degrees despite
lead or lead substitutes. Don't waste your time/money or risk
your head! See my article in <em>Austin-Healey Magazine</em>
Nov. 2020 "Get the Lead Out!" Hank<br>
-------------------- <br>
<br>
From: "Michael Salter" <a class="moz-txt-link-rfc2396E" href="mailto:michaelsalter@gmail.com"><michaelsalter@gmail.com></a> <br>
To: <a class="moz-txt-link-rfc2396E" href="mailto:healeys@autox.team.net"><healeys@autox.team.net></a> <br>
Sent: August 25, 2024 at 8:09 AM PDT <br>
Subject: [Healeys] Hardened seats in a cast iron 100 head </div>
<div>I am still using cast iron heads on both my 100's. Amazingly
neither have serious cracks as are so common on these.
<div>I am really picky and don't particularly like the different
sound that a 100 engine with an aluminium head makes so would
like to continue using these cast iron ones. </div>
<div>I'm contemplating installing hardened seats in one. </div>
<div>Hase anyone done this successfully?</div>
</div>
<div> </div>
<br>
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