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re: carburetor overflow hoses

To: datsun-roadsters@autox.team.net, ggerding@tconl.com
Subject: re: carburetor overflow hoses
From: walter@omni.sps.mot.com (Thomas Walter)
Date: Fri, 6 Aug 99 11:20:51 CDT
Gary,

How far down do the tubes extend. If you have rubber hoses
down below the frame, they create a good venturi effect for
lowering the pressure in the float bowls - which may result
in actually suckng some fuel down the vent tube.

The tubes should be dry.

As to the engine dying when you cover the end of the tube...
odd. I would suspect the fuel pressure coming into the
carb is too high. By closing off the end of the tube,
you would increase the pressure in the float chamber
to the point of forcing fuel up the JET into the carb.
Too rich, and the engine dies.

First:  The hoses should be routed down, but not into
        the airstream under the car.

Second: Are you running an electric fuel pump? Do you have
        a pressure regulator installed?

        If you have a stock mechanical pump, double check there
        is a 1/4" spacer between the engine and pump.

Third:  Time to check those needle & seat in the carb. Just
        Sounds like you're getting too much fuel in there.
        Either a bad, or sticky, seat or some dirt.

Typically when I park the roadster for the SUMMER (not too
much fun in this 100 degree August heat & high humidity)...
after a couple of months, when I first fire up the engine...
my overflows will leak. Just a matter of popping off the tops
of the float bodies, cleaning up the needle and seat with
a little carb cleaner to clean out the shellac that formed...
and I am on my way again.

Cheers,

Tom Walter  '67 2000
Austin, TX  '68 2000


>
>The bottom tips of my overflow hoses look wet all of the time!  I have not
>seen gas drip out but can see fumes coming out if the lighting is right.   Are
>these wet hose tips nornal?  I also noticed that if I put my finger over the
>end if the hose, the engine dies.  Is that normal?
>
>Thanks,
>
>Gary Gerding, 1967 SPL311, Omaha, NE
>
>

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