Posted by Clint Dixon on Saturday, February 19, 2005 at 9:47PM :
In Reply to: carburator/govenor questions posted by Jim Chance on Saturday, February 19, 2005 at 7:56PM :
If this problem has been happening only lately with the cold weather, it cold be because carb is icing up around the throttle plate upon start up. This can happen if your manifold heat control valve is not functioning properly or if it is rusted in the "summer" position. The engine has not run long enough for the intake manifold to warm up sufficiently. Ice/frost can form around the throttle plate and cause it to bind. I have had this happen even on cool damp summer mornings. Usually during cold weather, and with the heat control valve set in the "winter" position, enough exhaust manifold heat gets to the intake manifold and carburetor base to keep everything freed up.
If it is because of a weak governor spring, it would be the bigger one of the two. It could have become stretched and weakened. If this has happend, you should also be experiencing a dramatic reduction in top end speed.
If the engine runs good with the mixture screw turned all of the way in, it sounds like you have a manifold leak or a leak between the manifold and carburetor gasket. When you installed the rebuilt carburetor, did you use two gaskets and the stock thin restrictor plate? If not, the stud nearest to the firewall could be contacting the carburetor body and holding that end up far enough to not allow a good seal at the gaskets. With the nuts tightened all of the way down, you should be able to slip a credit card between the top of the stud and the underside of the carburetor casting directly above it.
Let us know what you find.
Clint
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