Dan,
Could you elaborate a little more on number (2) please? I have a modified rear manifold with no flapper valve, and I live in south Texas
Thanks!

Nice pic Reed! Is the front one a Dutra manifold, or a home fabbed unit?

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"Ja, Ich fahre ein altes auto."
'78 Volare 225
'67 Charger 318

Manifold heat is not primarily there to prevent carburetor ice-up or other driveability faults related to cold weather. It's there because evaporating gasoline under partial vacuum cools down the surfaces it touches, much the same way an air conditioner works or an aerosol can grows cold in your hand as you spray with them. The cooling effect is considerably stronger than it might seem just by thinking about it, and as a result liquid fuel can condense out on the manifold walls. That does bad things to driveability, performance, and economy. The manifold heat valve counteracts this effect by heating the floor of the intake manifold so liquid fuel will be vapourise before it hits the cylinders.

The cooling effect described is obviously more problematic when the air entering the intake is colder than when it is warmer, but it does not go away just because it's 100° outside. It's a normal operating condition of a carbureted engine.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Okay, thanks for the Response Dan! My Volare has had a bit of a rough idle when in gear, which I assumed was a vaccuum leak. I did wonder though, if my lack of manifold heat was one of the culprits.
However, and I do apologize if I'm hijacking the thread here, the idea is to heat the bottom of the intake manifold, not necessarily the bottom of the carb, is that correct?
Thanks for the info!

_________________
"Ja, Ich fahre ein altes auto."
'78 Volare 225
'67 Charger 318

The bottom of the carb doesn't really get heated much by the intake manifold heater.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Those manifolds are both completely homemade. I bought the front one and I made the back one. I don't know if they are completely sealed, but I will find out when they get mounted. I once had a Dutra, but I sold it.