Methods of Preventing Vapor Lock

by several Spitfire Mailing List members

Terry Thompson writes:

With the addition of a header next month and a set of dual HIF4's (which are overly susceptible to overheating of the bimetal element in the float bowl), I'm trying to think ahead and plan for overheating problems this spring.

Short of ordering the item from Rimmer bros. in England, does anyone have a source or a shadetree-mechanic replacement for the "Heat Shield" that deflects heat from the header away from the carb float bowls?

Any other ideas on how to reduce vapor-lock?

Michael Altomare responds:

I don't know about the heat shield, but I did try a couple of things that helped when I had vapor lock problems during the hot summers in Atlanta. First, I changed to an electric fuel pump. That makes sure that the fuel line is full of fuel instead of vapors. Second, I made sure that I replaced the engine compartment fuel line that was larger in diameter than it actually needed to be with the correct line. I haven't had any problem for years since doing those simple things.

Patrick Bowen's response:

I have been told that insulated cookie sheets (the type with the air pocket) work well. cut and fit to size.

Mark Milotay's response:

I used a Baker's Secret insulated cookie sheet. The smaller one fits perfectly between the cardboard valences and the block, sitting just over the exhaust manifold.

Mitch Johnson's response:

I don't know if you have one of these near to your location. But check out this web site. My friend did his header on his MGB, I had my spare intake manifold done with his stuff. Now I am going to have my header done. My friend was really impressed!

Terrence Banbury's response:

Check the routing of your fuel line. Try to keep it away from 'hot' parts of the engine. Even 1/2" of clearance is better than none. I've found that over time a fuel line may work it's way closer to the engine block.

Craig Smith's response:

One thing I did was to move the routing of the line from under the water pump to up and over the top of the head between the goose neck of the radiator hose and the valve cover. I also installed small pieces of hose secured to the metal line by wire ties. This keeps the line up above everything and the rubber hose pieces keep the line away and vibration free of the metal parts.

Go to the Rouges Gallery and you can see some pictures. The Bright metal thing is my sensor cable for the mechanical Temp guage. I though if I can get rid of as many electrical thingys the better.

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