Hi Warren,
I put the insulation blanket back between the valley pan and the manifold and also blocked the heat passages under the carb by putting a metal shim on both sides of the heat passages. Now, the problem has gone away, at least for a while.
By the way, stainess steel is actually better, I believe, as it has a lower thermal conductivity than Cast Iron and Aluminum.
See below. The stainless should keep the heat away from the carb better than cast iron or Aluminum.
Metal Deg. F T.C.
Cast Iron, gray 70 27 - 46
Aluminum, pure 68 118
200 124
400 144
Stainless Steel 68 7-26
Thermal Conductivity - k - is the quantity of heat transmitted, due to unit temperature gradient, in unit time under steady conditions in a direction normal to a surface of unit area. Thermal Conductivity - k - is used in the Fourier's equation.
a.. 1 Btu/(hr oF ft2/ft) = 1 Btu/(hr oF ft) = 1.731 W/(m K) = 1.488 kcal/(h m oC)
Regards,
Mark Lindahl
----- Original Message -----
From: Warren Anderson
To: chrysler300@xxxxxxxxxxxxxxx ; Mark Lindahl
Sent: Wednesday, September 09, 2009 12:40 PM
Subject: Re: [Chrysler300] Flooding of Carter 3256SA Carb - '63 300 Conv.
The heat riser valve in the exhaust manifold will help move exhaust gasses through the heat riser passage in the intake manifold. The system is critical to not so critical depending on where you live and how the car is driven. Street driven for short trips or in high altitude colder to cold climates (like where I live) the system is critical and if only for racing or in very mild to hot climates (like where I am from) the system is routinely bypassed or not so necessary. Street driven vehicles must have a heat riser chamber working properly for anything close to acceptable warm up performance.
Fuel we have available is no good for carbureted vehicles.
I built an aluminum plate that is larger than my carburetor in floor plan to transfer heat.. This is an old RV trick. This 1/16" plate is sandwiched between two gaskets. Seems to help some to a lot. Stainless steel is not what I would select for heat transfer . . . ?
Engine cooling system thermostats are necessary. I have found that the 160 deg F stat is too cold for normal driving schedules and a 192 deg is too hot for all but really cold season driving so I have settled on a 180 deg calibration for anything with a carburetor and without computer fuel/engine controls.
The thermostatic engine cooling fan drive must work properly.
FWIW I have experienced vapor locking, fuel boiling, with carbureted vehicles in winter, snowy weather. So, with my carbureted vehicles, I do what is reasonable and learn techniques to work around the situation as best can which includes my long ago developed practice of absolutely not touching the accelerator pedal on a hot restart. That and my aluminum plate is what works best for me..
Warren Anderson
Sedona, AZ
Hi All,
I have tried a few things to reduce/eliminate the boiling of gas in the carb bowls after hot weather driving and shut down of 383.
Within a few minutes, the carb gets so hot that the fuel is boiling and flooding occurs. I have seen it a few times.
The engine does not run hot during normal driving. Temp/Gas Guage seem to be calibrated with temp guage around the 1/2-3/4 mark.
At idle and normal driving speeds, the engine runs strong. Newer open chamber heads were installed about 18 months ago along with hardened seats for unleaded gas. I reinstalled the original valley pan and now have a 4 bbl. carb instead of the original 2 bbl.
Here is what I have tried.
Installed gasket between hood and radiator support: It looks good, but does not help my problem.
Installed new needle/seat in carb: Flooding still occurs, but somewhat less.
Waiting for stainless steel plate to install under carb to reduce heat transfer: will advise.
I have removed the spring from the exhaust manifold allowing for free movement of the valve: no change.
I took off the heavy metal air cleaner top and now have the air filter exposed using just a flat top: no change.
I also vaguely remember that some valley pans have the the heat passages blocked off to not allow heat back up to the carb.
Since I don't drive the 300 in the winter or much when it is cold, is this a good idea?
Are there certain valley pans with the heat passages cut out and some with them blocked off?
Any ideas would be helpful.
Regards,
Mark Lindahl
'63 300 Conv.
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