This is kind of a poll, or weigh in if you all have any wisdom on this. Why do my two 2bbl carb bases and carb risers get ice cold, condense and from time to time frost up. ? This has been in summer temps (80 degrees), or on cooler days (45 degrees). Ambient air temp does not really matter. I tend to take the car out on nice days so its not usually wet or humid out. The carb risers (outside of them) will develop a light frost on them. Then when the motor gets warmer it just becomes condensation. When I get home the bases and risers are for lack of a better term "soaked". Doesn't affect anything just a odd nuisance. Info: stock 59AB flathead, Twin 2bbl carbs a tad rich, 3.5" risers on a Hexagon manifold, no hood or sides in an AV8. Runs good and smooth, Not too hot, With 18in manifold vac, 12deg initial timing. Anyone else ever see this? Thoughts? Info?
If there is a way that you could get some heat to the spacers that would cure the problem. I had a Corvair with one of the spider intakes that mounted the carb over the engine cooling fan when I ran a Holley on it it turn into a big ball of ice when I changed to an AFB it wouldn't do it. I believe the AFB that has the float bowl around the venturies (spelling) kept it from icing up.
Mine on a riser would ice to the point of throttle sticking. You want something like this? http://www.mtfca.com/discus/messages/411944/478469.html?1411182714
A common problem in Michigan. No intake heat, no hood and no heat to the carbs. High humidity and you will get frost around the throttle bores from the air flow going by the plates and venturi. Gets real bad when the temps get into the forties and fifties. Have had to stop on the E-way and warm things up. Throttle stuck and black smoke out the back. Only solution is heat. Carbs closer to a warm intake or pipe hot air into carb inlet. I made a hose from the exhaust manifold to the carbs. Using corregated dryer vent type hose hose clamped to the exhaust manifold, to a box around the air filters. Looks funny, but works. Easily removed when you get to a show. Also had to do similar to my International backhoe so I can use in the winter..
What you're seeing is the result of Bernoulli's principle and the venturi effect, or some sort of technical **** like that. Moving air and vaporized fuel at high speed thru the carbs and risers creates a low pressure area that also reduces temperatures. This absorbs heat from the surrounding area and with enough humidity in the air, condensation, frost and ice can form. You've kind of got a miniature air conditioning system going on there. Only instead of freon you're changing gasoline from a liquid state to a vaporous state. This is the reason more modern engines have an exhaust crossover p***age built into the intake manifold and why many carbureted engines brought heated air from the around the exhaust manifold into the snorkel of the air cleaner. You might want to consider insulating the carb risers. A little frost won't hurt anything but if you're driving long enough on a cool and humid evening you might be surprised by having your throttles frozen open.
Wild stuff guys. That air conditioner ****ogy is kinda what i thought was going on. I have not yet experienced any "Snow balls" like you guys have. But now I can figure what system to mimic. Neat remedies to the problem. Glad to know I wasn't the only one with frosty carbs.
Do you suppose that there might be a way to criss-cross the upper radiator hoses so they're rerouted between or around the risers? Might be enough heat transfer to keep things thawed out as long as it doesn't cause fuel percolation in the float bowls. And it doesn't interfere with the throttle linkage.
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