Originally Posted by 68NovaSS
Umm, what's going to cause vaporization in a cold motor on a winter morning after you've shot a few raw fuel streams into it?
Getting started on cold damp days is a really big challenge. The choke that you don't have is put there to force a vacuum over the main metering circuit so extra fuel will flow into the engine. That combined with the idle flow is supposed to provide enough evaporated (vaporized) fuel to get the engine running. A liquid changing state to a vapor absorbs heat, this being the principle behind refrigeration/air-conditioning. Under the closed or nearly so throttle blades in the manifold a considerable vacuum forms which drops the fuel below its vapor pressure which also helps it turn from liquid to vapor. So all of this lowers the temperature of the mixture to where the water entrained as humidity with the incoming air condenses on the cold metal surfaces of the carb and intake forming ice. The whole point of the exhaust heat cross over in conventional intakes is to raise the temperature of the surfaces and the entering air is raised above the freezing temperature. It also forces vaporization of the fuel which allows a leaner starting mixture which is alot easier on pistons, rings, and cylinder walls.
Whew need a breath. Cold starting by its nature does not evaporate all the fuel being dumped into the engine, just enough to get it running. The fuel that remains as liquid is deposited onto the parts of and in the combustion chamber as carbon/coke (including valves and spark-plug), pushed with the blow-by around the rings taking the upper cylinder lube with it (resulting in fast wear of the parts in this area), delivered out the exhaust as unburnt hydrocarbons dumped into the air you breath.
Now since you don't have a choke, you're supplying this extra rich mixture with the accelerating pump, probably a power valve that turns on with very little manifold vacuum, and most likely richer main jetting than is really required. The sign of all this that you're currently seeing is carbon fouled spark plugs which can be fixed with a hotter heat range to burn the carbon off, this will probably not be suitable in summer even the poor excuse that passes for summer in the Northwest. It was suggested that you construct a heat riser tube from the headers to the air cleaner. This is a trick the OEMs use to get warm air air going soon after start up. These can be made controllable as the OEMs are so they shut off as the engine warms then pull cold air from outside. Another great OEM trick is to heat the engine oil with the coolant (an old big truck and industrial engine trick) This cuts the engines warm up from 10 to a couple minutes. The OEMs put a "cooler" most similar to that used by an automatic tranny into the return tank of the radiator. There are also commercially made units that tap into the thermostat bypass/heater hoses that are hugely effective toward getting the oil and engine up to operating temp quickly.
All this race stuff people get into of cold intakes, no chokes, open air cleaners, etc is fine on the race track when the engine is turning near red line RPMs and the mixture velocity thorough the carb and into the ports is at half a Mach number or better. But it isn't good for a street engine that can't use velocity and turbulence to chop cold fuel droplets into something that looks like a vapor. It is vapor that burns and makes power. If you can't cruise to work and back at WOT, then you gotta think out some other ways to get the motor happy and powerful.