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Old 06-29-2015, 11:59 PM   #33 (permalink)
Isaac Zackary
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Quote:
Originally Posted by oil pan 4 View Post
The old carbureted engines used a heat shroud around the 1 or 2 of the exhaust manifold exhaust primaries to give the carb some warm air almost immediately after startup.
This was just mostly so it would idle and not stall constantly right after a good cold startup.
The exhaust manifolds get real hot but its not very easy to get a high volume of really hot air off them.

To add to your post, starting in the 1970's these became thermostatically controlled so that changing air temps did't affect the air density and therefore the air fuel ratio. The thermostatic temp was usually around 110° F.
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