Carl,
Like Bart said, removing the shaft & riser, is an option.
Removing the shaft & heat riser valve does not put "full-on" heat to the intake.
Just the opposite.
It opens up the exhaust manifold, and turns the "heat-off" the (intake) from the preheating process.
If the valve sticks in the "heat-on" position, the valve is "closed". NOT GOOD!
Closed directs the hot exhaust gases to the intake manifold when the engine is cold.
Closed = heat on the intake.
If the valve sticks in the "heat-off" position, the valve is "open",
and directs the exhaust gases away from the intake manifold to the exhaust manifold.
Open = heat off intake.
In 1954, Chevrolet "determined that manifold heat control valve operation
is neither necessary nor desirable under normal temperature and operating conditions"........
"the heat control valve spring has been reversed so as to hold
the valve continuously in a "heat-off" position".
"If preheating of the incoming charge is desired for extreme cold weather
operation", reverse the spring.
