Subject: RE: Vapour lock problem. Was won't start
In-Reply-To: Your message of Wed, 19 May 1999 08:43:09 -0400
> I've heard this urban myth for a long time, but never had a car that
> vapor-locked to test it out. My WAG though, is that the clothespin acts as
> a heat sink, drawing just enough heat out of the line to overcome the vapor
> lock. It sure does look silly though.
>
SNIP
> -----Original Message-----
> From: dresden@tiac.net [mailto:dresden@tiac.net]
> >
> ><< An easy test for vapor lock is a simple wooden
> > clothes pin. Clamp it on the visible part of the line (before the carbs)
> and off you go. Yes, it is odd but it works. >>
> OK, how about a really far out SWAG on this one; when you put the
> clothespin on the line, it isn't strong enough to cut off the gas, but does
> change the diameter and shape of the line, creating some sort of Bernoulli
> effect, which makes the gasoline more able to either break up or move past
> the "vapour" locked portion?
!!!!!!!!!!!!!!!!
Whoa. Heat sink...don't want to start a flame war but wood is a notoriously
poor heat sink. Prove to me that the heatsink properties of a wooden
clothespin is the rationale.
Here's a test. If heatsinking the gas line would prevent vapo'u'r lock, then
wrap the offending region of the line in aluminum foil or some other
conducting metal (and aluminum is only ok in that realm). If the vapor lock
remains, the problem is not solved by a heatsinking clothespin. Rather the
Bernoulli explanation makes more sense (but is it right?).
Now that I think on this, putting aluminum foil on the line might exascerbate
vapor lock by
conducting heat into the line so that is not a good test either.
A better test would be to take a LARGE paper clip (metal), open it and wrap
it around the line. Then tighten it somewhat to constrict (not much) the
line. If the solution is to change the flow pattern, then this solution
should be equal to a clothesline and also solve it. If the problem were a
heat problem, then this solution might make the problem worse due to the
metal contact.
And I didn't even raise the issue of the heat conductivity of the fuel line
itself. Rubber in all its disguises is also a poor conductor.
I vote for the already mentioned change in flow configuration.
Bill
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