In a message dated 9/4/2004 3:16:05 PM Eastern Standard Time,
Woomerj@xxxxxxx writes:
What is the function of the the piece of tubing that comes out of
the choke return spring housing, goes down into the manifold, makes
a loop, and comes back out and forms a return bend with the hole in the
end about 2 inches from the top of the manifold? Is it supposed to suck hot
air into the return spring and make it expand and open the choke?
Any suggestios will be
appreciated.
Jim Woomer
Jim,
You are correct that the tube that goes from the chole houising down into
the EXHAUST manifold is to bring heated air to the choke coil, in order for
it to open up.
The choke coil is in fact a piece of bi-metallic steel that will "relax"
when heated and allow the choke plate to fall open.
The entire choke and fast-idle cam assembly should drop to the open
position freely when the engine is warm and the throttle is opened enough to
free the fast-idle cam.
The correct basic adjustment of the choke coil is at 75 degrees
F. (room temperature.) While tapping the carburetor to overcome
friction in the linkage, rotate the black bakelite housing until the choke just
closes. If you have a proper coil and housing assembly, this should bring
you to the center mark on the housing. Usually, you should set the coil
one notch richer than that.
A caution is that it is possible to insert the coil into the housing FOUR
different ways: The correct way is the one that "Hooks" the lever on the
choke shaft and "PULLS" it closed and brings it closed and near the center
set of marks. If you should perhaps install it "Flopped over", instead of
relaxing the choke as the engine heats up, it would tend to tighten it.
One further comment on the exhaust mainfold tubing: There is a
separate piece of tubing that goes completely through the exhaust manifold, so
that you would pull clean air into the choke housing. These were notorious
for burning through and allowing you to pull exhaust gasses through the choke
housing and the pull-off piston. That carbons them up and renders them
useless pretty rapidly. If the inside of the housing is carboned up, that
is the reason. In "Olden Times", we just installed a mechanical choke and
went on our merry way. That is one of the primary reasons the the later
choke coils were located in the well in the manifold.
Have a great weekend!
Joe Savard
Lake Orion, MI.
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