Carburetor/ smog problems

[DAVIS,BRIAN R]

Hello from Boise Idaho!

I had to get Amphi's exhaust "Smog Checked", and she failed!! Seems that the
carbon monoxide (CO) was too high at 2500 rpm's. (Idaho tests cars back to
1962!) The state limit is 500 PPM, and my car was running at about 750.

I checked a number of things in an effort to make it pass:

Removed air cleaner.
Leaned-out the idle mixture screw.
Made sure that the choke butterfly was completely open.

The engine runs fine, and I'm very hesitant to start taking the carb apart.
Yet I do have a problem when the engine is hot, and I wonder if it's related
to the high CO level.

When the engine is fully warmed up, if I shut it off for 5 or 10 minutes, It
will not immediately start until I crank it over several times. It's almost
as if the gas in the carb float bowl has drained out, and the fuel pump
needs to pump more gas into it for it to start.

So here's my theory....is it possible that when hot, some gas dribbles down
the throat of the carb and drains the float bowl? (Contributing to the
higher CO level, and contributing to the harder starting after sitting for a
while?)

Is a CO level of 750ppm at 2500 rpm really abnormally high?

Why would I have to crank it over several times when hot, but it starts like
a champ when cold? (and without using the choke I might add).

I noticed tonight some gas oozing out around the throttle butterfly pivot
point. The smell of gas was what got me looking. It sure seems that gas is
running down the throat of the carburetor and leaking out around the
throttle valve.

Any ideas anyone?.......

Thanks!

 

[fatmac99@mindspring.com]

I've heard for years a quick way to get a car to pass the emissions test is to
pour a quart of isopropyl alcohol into the gas tank. Now I would never admit to
doing this, but I can tell you to make sure it is aviator's alcohol, because the
stuff you buy at the store is 30% water; you might as well fill the tank with a
garden hose.

Luckily in Georgia the cars are tested only back to '75. When I lived in
Illinois, it was to '67.

Mike
64 Blue "Shipshape"