Ben,
I agree with Joe. You have carburetor icing. I had the same problem on a 64
Dodge with a 318 2bbl. It would stall at idle when warmed up and the weather
was very humid (100 %) and the temperature was just above freezing. After it
stalled, the heat from the engine would melt the ice and it restarted
easily. The air in the carb only needed to drop a couple of degrees to
freeze out some of the moisture. Especially in sleet storms. If it was a
little warmer, the moisture may condense as liquid, but would be blown away.
If it was a little colder, the humidity would be low enough to not cause a
problem. But I have a slightly different solution.
1. I would always add a can of Heat gas line antifreeze to the gas tank
of my 64 when this problem happened. The alcohol in the Heat would melt the
ice over the idle ports in the carb. My heat riser in the exhaust manifold
did work.
2. Putting exhaust heat in the intake manifold definitely helps
vaporize the fuel in the intake, but may not be the cure. This heat is below
the carb and in-rushing air will keep the carb cold enough for icing to
still take place. The in-coming air needs to be heated. In the 60's, all of
the auto manufacturers started using air cleaners with a duct that brought
heated air from a shroud around the exhaust manifold. A temperature
controlled flapper in the air cleaner snorkel attempted to blend hot and
cold air to achieve a constant temperature. Try to find one of these air
cleaner systems for a later model slant 6 engine.
Good luck,
Dave Homstad
56 Dodge D500
-----Original Message-----
From: Joe Savard [SMTP:JLSAVARD@AOL.COM]
Sent: Wednesday, October 27, 1999 11:36 PM
To: L-FORWARDLOOK@LISTS.PSU.EDU
Subject: Re: [FWDLK] Cold Running Problems, Also Damp Weather
Troubles
Ben,
The condition you are referring to is called "Icing". It is caused by the
expansion of the air that goes around the throttle plate at idle and road
load conditions. It generally occurs when the ambient air temperature is
slightly above freezing and humid. As the air expands beneath the throttle
plate, it cools to below freezing and cannot hold as much moisture as it can
above freezing. It deposits the excess moisture around the idle ports as
ice
and shuts off the fuel flow. It is apparent after the fast idle cam is off
and persists until the engine is fully warm.
The test for this condition is that when the engine dies at idle, DO NOT
touch the accelerator. Wait 30 seconds or so, and restart the engine
WITHOUT
touching the accelerator. If it then idles normally, it is because the ice
has melted.
The fix is HEAT. The manifold heat control must be operating properly or
all
hope is lost. The manifold heat control was always a problem due to carbon
buildup from the exhaust, even on fairly new vehicles. After 30 yeqrs or
so,
there is a good chance yours is frozen in the open position.
If you can spray a corbon solvent on the shaft and gradually work it until
it
frees up, your problem should go away. BE CAREFUL about how hard you twist
the counterweight, because it is not keyed in place and frequently twists
around the shaft before the shaft is free. DO NOT use oil because it can
cook on the shaft and make the problem come back sooner than it should.
After it is freed up, occasionally (While the engine is cold!) reach under
there and flop the weight back and forth to keep it free.
Hope this helps... Good luck!
Joe Savard
Lake Orion, Mi
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