[DML] Carburetion Saves The Day -- Cold Start Valve (David McKeen)

["content22207" <brobertson@xxxxxxxxxxxx>]

Nope: It uses engine vacuum.

The cold start valve works basically the same way carburetor venturi
work. A little dab of fuel, a little dab of engine vacuum, and you're
in the fuel delivery business.

The cold start valve isn't an "injector" at all, even though some
people call it that. As you correctly identify, it is nothing more
than an electrically opened valve. Once open, engine vacuum pulls fuel
through the "special nozzle" (DMC's words, not mine) and atomizes it.

Of course since the cold start valve is located after the throttle
plates, there's no way of metering its output. You couldn't run the
engine on the cold start valve alone.

BTW: The cold start valve is yet another hole in your vapor lock
theory. The engine sucks through it: Vapors first, liquid fuel second.
Vapor lock is something of a red herring since the introduction of
MBTE (which I believe has been superceded by an even better, and even
more expensive, additive).

There has been speculation on this List that the cold start valve
doesn't deliver fuel to all 6 cylinders, or doesn't do so equally.
That's a misnomer, probably due to its offset entry into the manifold.
If you follow the vacuum passages you'll see that every cylinder port
has a little hole right before the O ring through which fuel is
pulled. Brass plugs at both ends of the manifold are the ends of the
driver and passenger side runners.

I believe one of your other messages confused when the cold start
valve is opened. It is a cold engine device, not warm. Owners who open
it purposefully on a warm engine are using some slight of hand to get
around rest pressure problems. 

Bill Robertson
#5939

>--- In dmcnews@xxxxxxxxxxxxxxx, "bitsyncmater" <david.mckeen@...> wrote:
>
> um....doesn't the cold start valve require some fuel pressure?
> 




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