<div dir="ltr"><div class="gmail_default" style="font-size:small">The video length? That's why they invented fast forward buttons, progress sliders, etc.</div><div class="gmail_default" style="font-size:small"><br></div><div class="gmail_default" style="font-size:small">I haven't measured it, but I'll guess our underhood temps while moving, or even while idling with our poorly positioned fans running, is not high enough to boil the fuel. When we stop the engine and the airflow pretty much stops (except for what escapes through the hood gaps, etc), then the air temp goes up, to the vicinity of the temp of that big hunk of iron below the carb. A spacer may reduce the conducted heat, but if the air all around the carb is hot, the carb temp will go up.</div><div class="gmail_default" style="font-size:small"><br></div><div class="gmail_default" style="font-size:small">For an experiment I added a drain to the carb vent, and did see fuel coming out after stopping. This weekend I hope to open the carb and check the fuel level, etc. I used my IR thermometer to read temps on stuff that was nearly black, and there were many spots that were initially well over 170, some even after 15 minutes with the hood open.</div><div class="gmail_default" style="font-size:small"><br></div><div class="gmail_default" style="font-size:small">My first generation Jetta had large flexible flaps over large holes in the panel the radiator mounted on. The would apparently open when the car was in motion, but close when the car stopped, to prevent hot air recirculation.</div><div class="gmail_default" style="font-size:small"><br></div><div class="gmail_default" style="font-size:small">I already thought of using the electric fan many of us have as a "bilge blower" (like on boats) on hot restarts.</div><div class="gmail_default" style="font-size:small"><br></div><div class="gmail_default" style="font-size:small">Stu</div></div><div class="gmail_extra"><br><div class="gmail_quote">On Tue, Sep 15, 2015 at 2:48 PM, Tom Witt via Tigers <span dir="ltr"><<a href="mailto:tigers@autox.team.net" target="_blank">tigers@autox.team.net</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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<div>I finally got around to watching this video. It was like watching paint
dry. It could have been 30 seconds long, not 20 minutes. But anyway (it’s not
Stu’s fault), it did eventually shows the gas boil at a low temperature.
I’ll just throw these things out there:</div>
<div> </div>
<div>1. No one ever mentions it, but there has to be some cooling effect of both
from the air being drawn into the carburetor and the evaporation effect of the
gas (like when you apply rubbing alcohol to your body). Then again,
without cold air ducting..., maybe not.</div>
<div> </div>
<div>2. A cooling effect likely offsets some of the heat soak while the car is
in use. However, when the engine is stopped that cooling also ceases.</div>
<div> </div>
<div>3. It would seem best to isolate and insulate the carburetor from the rest
of the engine compartment. This, however would require some type of hood
scoop (or duct) and and an isolation enclosure under an already crowded
hood.</div>
<div> </div>
<div>4. I’m wondering if the horn opening block off plates some use (that work
at idle/stopped) to prevent recirculation are a detriment at higher speeds not
allowing cooler air to pass through the engine compartment? I’ve always
through a spring loaded door seemed a better concept. Closed at an idle/stopped
condition, but opened from the flow of air as the car moved forward.</div>
<div> </div>
<div>5. If anyone is interested, some of the 280Z’s had a fan and ducting that
blew air onto the injector rail. The concept would seem somewhat adaptable to
blowing cool air on the carburetor after the car shut off. A 555 Timer could
control the run time after shut-off.</div>
<div> </div>
<div>It seems any attempt for correction deviates from a stock appearance. And,
a crowded area under the hood doesn’t leave many options for isolation or
ducting. Has anyone run without their hood to see it it makes a
difference?</div>
<div> </div>
<div>Just some rambling thoughts.</div>
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<div><b>From:</b> <a title="tigers@autox.team.net" href="mailto:tigers@autox.team.net" target="_blank">Stu via Tigers</a> </div>
<div><b>Sent:</b> Friday, September 11, 2015 5:42 PM</div>
<div><b>To:</b> <a title="Tigers@autox.team.net" href="mailto:Tigers@autox.team.net" target="_blank">Tiger Net</a> </div>
<div><b>Subject:</b> [Tigers] Carb Fire Research</div></div></div>
<div> </div></div>
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<div class="gmail_default" style="FONT-SIZE:x-small;COLOR:rgb(0,0,0)">I've been
doing some research, and found an interesting video:</div>
<div class="gmail_default" style="FONT-SIZE:x-small;COLOR:rgb(0,0,0)"> </div>
<div class="gmail_default" style="FONT-SIZE:14px;COLOR:rgb(0,0,0)"><font size="1"><a href="https://www.youtube.com/watch?v=d7AkcjnCTVU" target="_blank">https://www.youtube.com/watch?v=d7AkcjnCTVU</a></font><br></div>
<div class="gmail_default" style="FONT-SIZE:14px;COLOR:rgb(0,0,0)"><font size="1"><br></font></div>
<div class="gmail_default" style="FONT-SIZE:14px;COLOR:rgb(0,0,0)"><font size="1">To summarize, this guy does a good experiment that proves that some
components of normal gasoline boil at around 170F.</font></div>
<div class="gmail_default" style="FONT-SIZE:14px;COLOR:rgb(0,0,0)"><font size="1"><br></font></div>
<div class="gmail_default" style="FONT-SIZE:14px;COLOR:rgb(0,0,0)"><font size="1">Our engines are usually well above this, so when we stop it's safe to
assume that the underhood temperatures spike, heating up our carbs, and
everything else. So there could easily be some boiling in the carb
bowl. And once the 170F components boil off, the temperature rises
even more. When trying a hot restart, new fuel is introduced to the much
hotter carb when the pump comes back on, perhaps there could be a few moments of
additional, perhaps more violent boiling, blowing vapor and fuel out the
vent.</font></div>
<div class="gmail_default" style="FONT-SIZE:14px;COLOR:rgb(0,0,0)"><font size="1"><br></font></div>
<div class="gmail_default" style="FONT-SIZE:14px;COLOR:rgb(0,0,0)"><font size="1">Last weekend I tried recreating the problem. Similar hot day, drove
around the same loop, etc. Parked and waited 10 minutes, about the same
time as before. I had cleaned the top of the carb, so it was obvious that
nothing had come out when I opened the hood and looked But listening
closely, I thought I could hear a faint sizzling sound from somewhere within the
carb... I did not try a restart, since I hadn't seen this video at
that point.</font></div>
<div class="gmail_default" style="FONT-SIZE:14px;COLOR:rgb(0,0,0)"><font size="1"><br></font></div>
<div class="gmail_default" style="FONT-SIZE:14px;COLOR:rgb(0,0,0)"><font size="1">Any opinions?</font></div>
<div class="gmail_default" style="FONT-SIZE:14px;COLOR:rgb(0,0,0)"><font size="1"><br></font></div>
<div class="gmail_default" style="FONT-SIZE:14px;COLOR:rgb(0,0,0)"><font size="1">Stu</font></div></div></div></div></div></div></div>
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