<div dir="auto">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’s 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,</div><div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Thu, 6 May 2021 at 9:52 PM, Michael Salter <<a href="mailto:michaelsalter@gmail.com">michaelsalter@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><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></div></div><br><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" target="_blank">ahmg@aol.com</a>> wrote:<br></div><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>
Sent from my iPhone<br>
</blockquote></div>
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