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Clothespins on fuel lines – fact or fiction?

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Photo by Matt Litwin.

So the conversation regarding the Pochon-Davignon family’s 2CV road trip went on a tangent into bush remedies for old car mishaps, and plenty of folks weighed in on the feasibility of using mashed-up bananas as a replacement for engine oil. And from there it veered off on another tangent, this one regarding the urban legend of placing clothespins on fuel lines to combat heat soak, thanks in part to Silvaire’s suggestion of a bush remedy roundup article.

As far as cheap and cheerful cures for fuel system vapor lock, the effects from putting clothespins on a fuel line or a wet grapefruit half over a fuel pump are both functional and scientifically valid remedies.

Personally, I first encountered this remedy several years back when writing up Mike Bretsch’s 1961 Pontiac Catalina, which we featured in the March 2012 issue of Hemmings Muscle Machines. Matt Litwin’s photos of said Catalina featured a sextet of clothespins on the 421’s dual quads (as seen above). Discussion around the office dismissed the clothespins as nonsense, akin to those static strips people would hang from their rear bumpers or those magnets that flim-flam artists claimed smoothed out fuel flow or some such nonsense.

But then Jules responded with an angle we didn’t think of: aluminum clothespins.

Just a note on the “vapor lock” on ford flathead v-8’s…yes the Alluminum clothes pins worked well by providing a “heat sink” on the metal fuel lines, they dissapated the heat away and permitting the fuel to become cooler.

Except that doesn’t explain later uses of wooden clothespins, and as Allan Kittleson wrote:

Silvaire, I agree on the use of wet grapefruit (or a wet anything) to get some evaporative cooling, but I always figured wooden clothespins wouldn’t do much because wood is an insulator not a conductor of heat.

Silvaire pointed out, however, that wooden clothespins might not be a bad thing.

Clothespins on the fuel line work because they are insulators. The fuel absorbs less heat as it flows through fuel lines located in a hot environment.

When conditions are near a tipping point it doesn’t take much, and just a little might be just enough.

The question to consider, then, is whether underhood temperatures are hot enough to cause the rise in temperature and the resulting phase change in gasoline or whether the underhood temperatures are cool enough to alleviate that phase change. In which case, wooden and aluminum clothespins, respectively, might be the better choice.

Then again, as Allan Kittleson pointed out, there might be a better explanation behind such bush remedies:

A big problem with a column like this would be separating fact from fiction! So many of these kinds of stories are mere urban legends! They either only happened in someone’s fertile imagination, or were tried but failed miserably and the perpetrator wouldn’t admit defeat. As an example, I think some vapor lock cures worked because the car cooled down while the driver was fiddling around and he attributed success to his “cure”.