If you're willing to wait a few minutes for the coolant to get hot, then wait awhile more for that heat to transfer itself through the intake to actually begin warming the fuel mixture, you've got more patience than most of us. 100-something degree water VS 1,000+ degree exhaust gas- - - - -which one is going to do a better job of keeping the fuel vaporized?
The some atomized fuel (ie, very small liquid fuel droplets) will vaporize (ie, become gaseous fuel) all by itself with high manifold vacuum and some will remain atomized until vaporized in the combustion chamber..
While it does take longer for water to reach operating temperature, the entire manifold doesn't have become 195° for the engine to feel warm. Even when the coolant is fully cold, it still has some heat in it and, as the engine runs, it continues to gain heat. The important thing is that the area directly under the carburetor is warm enough to vaporize most of the fuel that falls out of the airstream so that it doesn't form a puddle on the floor of the intake manifold.
Jerry,
You don’t mention that both the headers and the factory manifold will get HOT no matter what heat riser you use. That heat is essentially directly below the intake and will warm the intake by ? ? ? is CONVECTION the right word? So I’m sorta curious as to what the IDEAL temperature for an inline intake would be? I seem to think the R&D department decided that “too hot” was bad, so they designed the heat riser to close so it would limit heat exchange after the engine was up to temp.
Without a manifold heat control system (ie, header-equipped engines), the intake manifold will warm up through CONDUCTION from the cylinder head. The intake manifold's temperature will obviously decrease from the cylinder head to the carburetor because of air flow and vaporizing gasoline.
The temperature of the intake manifold just needs to be hotter than the boiling point of the majority of components of gasoline. Light components (like ethanol) have very low boiling points (which cause percolation in the carburetor and vapor lock in the fuel pump) and heavier components have much higher boiling points. The heaviest fractions of gasoline evaporate in the 300-400°F range so having a 200°F
hot spot would not be too hot. See
Vapor Lock
