Lots of people assume that their Weber DCOE's need rebuilding when
they do not. The only reason I know that a DCOE needs to be rebuilt is
because the idle passages get clogged and a simple blast of compressed
air will not clean them out. The throttle bearings do not wear out, and
the DCOE's will always leak whether you rebuild them or not.
If you find that you have a cylinder that does not respond to any
adjustment of the idle mixture screw, then your carburetor may need a
thorough cleaning, also known as a "rebuild". Before removing your carb
you should be sure that it is correctly synchronized as a cylinder may
not be firing if it is not getting any air. Also, you can usually remove
the top of the carb, the idle jet, the progression hole cover and the
idle mixture screw, and blow every thing out with compressed air before
pulling the carb off the car. Most of the time this will work, so a
"rebuild" will not be necessary.
Assuming the above steps did not work then you will have to remove
and disassemble the carburetors. There is no need to remove the thottles
or throttle bearings. Dunk the carburetor body in carb cleaner for several
hours. Remove the carb body and rinse ot off with a solvent less caustic
than carb cleaner. Pay special attention to rinsing out the throttle bearings.
Next liberally douse the throttle bearings with WD-40 or the equivalent.
Now blow the whole mess with compressed air. Ancient Alfa carburetors will
need to have the carburetor idle passages drilled to get the scuzz out.
The passages can be easily replugged with lead from fishing weights.
It is fairly simple to clean and reassemble the rest of the carb with
the aid of an exploded parts diagram. With practise I can do the whole
job in about three hours per carb.
Now for the bad news. Over half the time I do this job the carburetor
still will not work. The carburetor still will not deliver the correct air
and fuel mixture to the cylinder at idle. If I install a new carburetor
the cylinder will fire normally, so the problem is definitely in the
carburetor. If any of you whiz kids can tell me why this happens then
I will gladly reward you $200.
The lesson behind all this is is that it seldom pays to rebuild DCO(E's
if your time is worth commercial rates because there are too many returns.
Most people are better off purchasing new carburetors. If your DCOE's need
throttle butterflies or bearings then I can guarantee you will be better
off buying new carburetors, but it is very rare that anybody needs these items.
In the words of a famous race mechanic "just because its rebuilt don't
mean its FIXED".
Happy Motoring,
Charlie Rockwell
World Famous Legend In His Own Mind
|