Re: Fish Carbs

[jlandry@domain.elided (John A. Landry)]

The black helicopters hovering over the house recorded tsm1@domain.elided (Tom
Mandera) whispering:

>John H.'s description of the carb fully vaporizing the fuel sounds a lot like..
>
>the wire mesh mod a few folks have made to their 'Binders.  In fact, I
>recall Mr. Landry was playing around with it.. what was the verdict on that
>again, John?

I really haven't finished experimenting with it yet to comment.  I have all
of the materials on hand to do some extended experiments, but I'll have to
admit to being to lazy to make it a top priority.  All I've done thus far
is fabricated one set of screens and tried them briefly when I still was
using the stock 2-barrel Holley 2210C.  I detected no difference in fuel
economy.  I've since learned I wasn't using the correct type of screening
material (supposedly) and I then got sidetracked with other projects like
my Edelbrock carb and 4-barrel manifold.

In my opinion the screen *theory* has merit, but I'm not sure with modern
carbs it will make much of a difference... but I'm still going to try it at
some point.  You see, one of the biggest carburetion challenges and issues
of gasoline fueled engines is vaporizing the fuel and keeping it that way
until fully burned.  Fuel manufacturers have spent countless years studying
and blending fuel formulations that strive to assist in this goal.  As far
as the screen idea goes, it's sound theory to try and create a low pressure
area in the manifold to cause additional air cavitation and further fuel
vaporization.  But it seems like modern carb designs do a pretty thorough
job atomizing the fuel in the first place.  Holley has had several design
breakthroughs over the years to increase fuel vaporization efficiency of
their carbs.  Heck, that's what a carb manufacturers job is all about.  So
maybe back in the early less efficient days of carbs the screens made a big
difference, but I'm really not sure now days.  But as I said, I'll try
anyway.

An interesting note is that propane and natural gas powered vehicles don't
have this problem... the fuel is fully vaporized when entering the manifold
and stays that way!  Gasoline easily precipitates out and that's why you
have to have the manifold heated, etc.  During cold startup, lots of
gasoline falls out of vaporization and pools in the manifold and cylinders.
This is why starting is such a pain when ambient temps get really cold.
The design of the gasoline blend has a big effect at what point the fuel
becomes hard to vaporize and ignite.  This is why you have winter and
summer blends of fuel in many parts of the country.  Draw through turbo and
super charging really helps keep fuel vaporized.  Of course fuel injection
eliminates most of these issues anyway.

Regards,

John
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