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I'm having serious vapor lock issues and don't know what else to try.

Car is a 65FB. 289 w/ cam, worked iron heads, alum intake, Holley 600 dbl pumper. Triple Flow radiator from US Radiator. At 100 degrees outside, w/ AC on, water temp is around 205.

In attempts to remedy the vapor lock, I have added a non-metallic spacer with a holley heat shield under the carb, wrapped my fuel lines w/ some $5/foot insulation from summit, and even installed a 400-cfm electric fan that blows out a hole in my inner fender to vent heat out of the engine compartment.

The fixes above have so far prevented vapor lock from occurring under all driving conditions. However, if I shut it down during the heat of the day, after about 15 or 20 minutes it will not start.

I need help bad. I'm open to any suggestions.

Thanks.
 

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Vapor lock and hard hot starting arent necessarily the same thing. It is possible that a car would vapor lock after shut down on a hot day......but hard hot start could also be an improper idle mixture (among a few other carb maladies...bad float valves come to mind).


Many mustangs dont experience vapor lock in the hottest climates.....but for the sake of argument, Ill run down contributing factors for vapor lock.


Any metal part of the fuel system that gets close to the engine (especially close to the exhuast) can contribute. Obviously, the fuel pump being mounted to the block raises the temp of the fuel somewhat.

Low fuel pressure makes matters worse.
 

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Have a look at the float levels, condition of the floats and the float valves themselves. Hot start failures, assuming ignition and starter are okay, are almost always related to either boiling raw fuel into the engine, flooding it. The level can also be so low that the fuel all boils away, but this isn't too common. It will indeed be exacerbated by a vapor lock however.

As long as you're at it, why not check the timing too ?
 

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First off this engine is too warm.If you have over bored .040 or more give up.These engines can not be cooled with any radiator that I have found.67 up can cool with b/b rad.I have had several 4-5-6 mustangs that on a .040 over bore could not be cooled down.The longer you drive the hotter they get.Error in design I guess.Second check float level and fuel pressure,should be at least 6 lbs.Good luck on finding your problem.SCOTT
 

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If it is truely vabor lock, I believe you can use an electricl fuel pump to push the fuel into the fuel bowl of the carb. You have alredy been given the cause of vapor lock, but what it is, is the fuel pump cannot push vapors, nor prime itself with liquid fuel. an electric fuel pump from further down the fuel system where it is cooler, will be able to push the fuel into the carb.
 
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