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Re: [Healeys] Vapor lock gas

To: Michael Salter <michaelsalter@gmail.com>
Subject: Re: [Healeys] Vapor lock gas
From: Alan Seigrist <healey.nut@gmail.com>
Date: Thu, 6 May 2021 22:02:25 +0800
Cc: "healeys@autox.team.net" <healeys@autox.team.net>
Delivered-to: mharc@autox.team.net
Delivered-to: healeys@autox.team.net
References: <4FD9EA26-9409-4A05-B8ED-57B5E080199D.ref@aol.com> <4FD9EA26-9409-4A05-B8ED-57B5E080199D@aol.com> <CAB3i7L+Q==RmaqOt4P8v8P72B3dYqHsLDY2=_9R3Qif__m0AYA@mail.gmail.com>
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I have found that having the header and miniature heat shield to be ceramic
coated makes a huge difference in the engine bay but then transfers heat to
the exhaust, so it=E2=80=99s only good if you have an SS exhaust system and=
 then
you need to insulate around the pump as Michael has said.  i just wrap
header tape around the exhaust pipe in that area and that is also effective=
,

On Thu, 6 May 2021 at 9:52 PM, Michael Salter <michaelsalter@gmail.com>
wrote:

> 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.
> With the 100 there are 2 distinct issues.
>
> Firstly, because the fuel pump and its associated lines are directly abov=
e
> 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 circulati=
on
> 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  sufficien=
t
> volume of vapour to exceed the rate of its production by the boiling
> process.
>
> Secondly the carburetor float chambers and the small fuel passage to the
> jet are very close to the exhaust manifold.
> The manifold radiates lots of heat which heats them. Again when the car i=
s
> moving at a reasonable pace the incoming air through the grille and aroun=
d
> 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.
>
> 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 th=
e
> pump.
>
> 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.
>
> For the most part neither of these modifications are visible and I have
> found that fuel delivery issues, although not completely eliminated, are
> manageable.
> 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 tha=
t
> will be visible.
> Hope that helps, others may have found better solutions.
>
> M
>
>
> On Mon., May 3, 2021, 2:58 p.m. Ken Fleming, <ahmg@aol.com> wrote:
>
>> 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 an=
d
>> Pistons has always suffered from what I call vapor lock of gas. Especial=
ly
>> in hot weather .
>> I am assuming the heat is from
>> 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 se=
em
>> most of them not to have same problem. I do have a heat sheild added wit=
h
>> little result.
>> I am at a loss as to
>> What to do
>> Next , but have you experienced this and have any suggestions. Are my
>> assumptions
>> Correct on heat causing the issue.  Could today=E2=80=99s quality if gas=
 be a
>> issue?
>> I recall reading this was a common issue for 100=E2=80=99s to have vapor=
 issues.
>> Ken
>>
>> Sent from my iPhone
>>
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<div dir=3D"auto">I have found that having the header and miniature heat sh=
ield to be ceramic coated makes a huge difference in the engine bay but the=
n transfers heat to the exhaust, so it=E2=80=99s only good if you have an S=
S exhaust system and then you need to insulate around the pump as Michael h=
as said. =C2=A0i just wrap header tape around the exhaust pipe in that area=
 and that is also effective,</div><div><br><div class=3D"gmail_quote"><div =
dir=3D"ltr" class=3D"gmail_attr">On Thu, 6 May 2021 at 9:52 PM, Michael Sal=
ter &lt;<a href=3D"mailto:michaelsalter@gmail.com";>michaelsalter@gmail.com<=
/a>&gt; wrote:<br></div><blockquote class=3D"gmail_quote" style=3D"margin:0=
 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir=3D"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 w=
here it becomes a problem.=C2=A0<div dir=3D"auto">With the 100 there are 2 =
distinct issues.=C2=A0</div><div dir=3D"auto"><br></div><div dir=3D"auto">F=
irstly, because the fuel pump and its associated lines are directly above t=
he exhaust pipe, hot air heats them. The fuel in the suction side of the pu=
mp has, effectively, a lower boiling point than it would at atmospheric pre=
ssure. This fuel tends to boil if there isn&#39;t sufficient air circulatio=
n 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=C2=A0 suff=
icient volume of vapour to exceed the rate of its production by the boiling=
 process.</div><div dir=3D"auto"><br></div><div dir=3D"auto">Secondly the c=
arburetor float chambers and the small fuel passage to the jet are very clo=
se to the exhaust manifold.=C2=A0</div><div dir=3D"auto">The manifold radia=
tes lots of heat which heats them. Again when the car is moving at a reason=
able pace the incoming air through the grille and around the radiator is su=
fficient to maintain the carburetor at a low enough temperature to prohibit=
 boiling but, again when stopped in traffic this doesn&#39;t happen.</div><=
div dir=3D"auto"><br></div><div dir=3D"auto">I have managed to eliminate th=
e first problem by installing a insulating sleeve from a modern car&#39;s A=
C hose over the fuel line from the tank to the pump.</div><div dir=3D"auto"=
><br></div><div dir=3D"auto">For the second I have made small heatshields f=
rom 24 gauge galvanized steel to shield as much as possible of the carburet=
ors from the radiated heat. This has helped considerably but not completely=
 eliminated the problem.=C2=A0</div><div dir=3D"auto"><br></div><div dir=3D=
"auto">For the most part neither of these modifications are visible and I h=
ave found that fuel delivery issues, although not completely eliminated, ar=
e manageable.=C2=A0</div><div dir=3D"auto">I am considering installing a sm=
all blower and duct sourcing air from behind the grille to see how much dif=
ference that makes but if course that will be visible.</div><div dir=3D"aut=
o">Hope that helps, others may have found better solutions.=C2=A0</div><div=
 dir=3D"auto"><br></div><div dir=3D"auto">M</div><div dir=3D"auto"><br></di=
v></div><br><div class=3D"gmail_quote"><div dir=3D"ltr" class=3D"gmail_attr=
">On Mon., May 3, 2021, 2:58 p.m. Ken Fleming, &lt;<a href=3D"mailto:ahmg@a=
ol.com" target=3D"_blank">ahmg@aol.com</a>&gt; wrote:<br></div><blockquote =
class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid=
;padding-left:1ex">Michael , I thought you maybe have experience this ans h=
ave 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 pla=
y a role but I could be wrong . I have asked other owners and they seem mos=
t of them not to have same problem. I do have a heat sheild added with litt=
le 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 assum=
ptions<br>
Correct on heat causing the issue.=C2=A0 Could today=E2=80=99s quality if g=
as be a issue?<br>
I recall reading this was a common issue for 100=E2=80=99s to have vapor is=
sues. <br>
Ken<br>
<br>
Sent from my iPhone<br>
</blockquote></div>
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