Vaporlock and the ensuing conversations

[carolinamudwalker]

They are adding BUTANE to our gas now to get rid of it. Before the EPA the refineries just burned it off It only causes problems in an open fuel system as in carburetors. The zenith carb is cast iron and obsorbs a lot of heat. The after market carbs like the tilli not so much. The 1/4 inch spacer should help.

[sjhark]

My first car was a 1975 Plymouth Duster that I shoehorned a 383 big block that took up every inch of the engine bay. Man, did it heat up! I ran a 4 barrel Holley and had a lot of problems with vapor lock. I fixed the problem with an aluminum plate heat shield and a phenolic spacer between the carb and the heat shield. I wonder if a similar setup, with the shield running down between the engine and carb, would work...

[steve s]

Originally Posted by carolinamudwalker

They are adding BUTANE to our gas now to get rid of it. Before the EPA the refineries just burned it off It only causes problems in an open fuel system as in carburetors. ....

To the extent that butane (C4H10) is being added to gasoline, it's not likely to get rid of vapor lock. On the contrary, it would be added in winter time to INCREASE the volatility (lower boiling point/increase vapor pressure) to help with cold-engine starts. In the summer time, such low molecular weight hydrocarbons will promote vapor lock, and even more so in the presence of ethanol, which tries to drive the more volatile hydrocarbon fractions out of the liquid into the vapor phase.

[Crankster]

I believe he's saying they add Butane to gasoline to get rid of it in the sense it's sort of a waste product, not that it does anything good for vapor lock.

The wooden clothes-pin trick works, though as I understand it not due to any heat sink action. They act as insulators.

[daren007]

Just open the hood for a few minutes after stopping until you get this problem sorted out. If you are using todays fuels you will have problems when the engine heat soaks.

[steve s]

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Originally Posted by Crankster

I believe he's saying they add Butane to gasoline to get rid of it in the sense it's sort of a waste product, not that it does anything good for vapor lock.....

Upon re-reading, I think you're right about what he meant--the "it" was butane, not vapor lock.

Ideally, all of the butane and other fractions that must be flared away could be incorporated into useful fuel. However, I believe that the addition of ethanol to gasoline, if anything, has decreased the amount of butane that can be included because of ethanol's effect of increasing gasoline's vapor pressure. As ethanol itself has a lower vapor pressure than gasoline, this is quite counter-intuitive.

[Mike V. Florida]

Why doesn't the bubble just travel back up to the tank?

[RockHillWill]

The pressure differential will determine the direction of travel.

[steve s]

Originally Posted by Mike V. Florida

Why doesn't the bubble just travel back up to the tank?

Even bubbles can be sticky--why not?

Examples of such metastability are all around us--lots of things that "should" happen either happen immeasurably slowly, or erratically and unpredictably, or not until it's given a tickle of some sort, or maybe not at all. My favorite example is the fact that the organic world and its inhabitants, bathed in a sea of oxygen as it is, doesn't burst into flames, as would be predicted if things were as simple as energy (i.e., "should") being in charge.