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re: "Methanol[sic] lowers the boiling point ..."<br>
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Typo?<br>
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<div class="moz-cite-prefix">On 5/6/2021 6:51 AM, Michael Salter
wrote:<br>
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<blockquote type="cite"
cite="mid:CAB3i7L+Q==RmaqOt4P8v8P72B3dYqHsLDY2=_9R3Qif__m0AYA@mail.gmail.com">
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<div dir="auto">Hi Ken, yes I think everyone with a 100 has
encountered fuel delivery issues with modern fuels. Methanol
lowers the boiling point of petrol to a point where it becomes a
problem.
<div dir="auto">With the 100 there are 2 distinct issues. </div>
<div dir="auto"><br>
</div>
<div dir="auto">Firstly, because the fuel pump and its
associated lines are directly above the exhaust pipe, hot air
heats them. The fuel in the suction side of the pump has,
effectively, a lower boiling point than it would at
atmospheric pressure. This fuel tends to boil if there isn't
sufficient air circulation to keep the pump and lines cooled,
as occurs while stopped in traffic on a hot day. True vapor
lock occurs because the pump will not pump sufficient volume
of vapour to exceed the rate of its production by the boiling
process.</div>
<div dir="auto"><br>
</div>
<div dir="auto">Secondly the carburetor float chambers and the
small fuel passage to the jet are very close to the exhaust
manifold. </div>
<div dir="auto">The manifold radiates lots of heat which heats
them. Again when the car is moving at a reasonable pace the
incoming air through the grille and around the radiator is
sufficient to maintain the carburetor at a low enough
temperature to prohibit boiling but, again when stopped in
traffic this doesn't happen.</div>
<div dir="auto"><br>
</div>
<div dir="auto">I have managed to eliminate the first problem by
installing a insulating sleeve from a modern car's AC hose
over the fuel line from the tank to the pump.</div>
<div dir="auto"><br>
</div>
<div dir="auto">For the second I have made small heatshields
from 24 gauge galvanized steel to shield as much as possible
of the carburetors from the radiated heat. This has helped
considerably but not completely eliminated the problem. </div>
<div dir="auto"><br>
</div>
<div dir="auto">For the most part neither of these modifications
are visible and I have found that fuel delivery issues,
although not completely eliminated, are manageable. </div>
<div dir="auto">I am considering installing a small blower and
duct sourcing air from behind the grille to see how much
difference that makes but if course that will be visible.</div>
<div dir="auto">Hope that helps, others may have found better
solutions. </div>
<div dir="auto"><br>
</div>
<div dir="auto">M</div>
<div dir="auto"><br>
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<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Mon., May 3, 2021, 2:58
p.m. Ken Fleming, <<a href="mailto:ahmg@aol.com"
moz-do-not-send="true">ahmg@aol.com</a>> wrote:<br>
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<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">Michael , I
thought you maybe have experience this ans have a solution .
On my Bn1 which is M spec with carbs, advance distributed,
LeMans Cam and Pistons has always suffered from what I call
vapor lock of gas. Especially in hot weather . <br>
I am assuming the heat is from<br>
Manifold and it placement near carbs or fuel pump/ battery
near exhaust play a role but I could be wrong . I have asked
other owners and they seem most of them not to have same
problem. I do have a heat sheild added with little result.<br>
I am at a loss as to<br>
What to do<br>
Next , but have you experienced this and have any suggestions.
Are my assumptions<br>
Correct on heat causing the issue. Could today’s quality if
gas be a issue?<br>
I recall reading this was a common issue for 100’s to have
vapor issues. <br>
Ken<br>
<br>
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