You are confusing the heat stove or air intake preheat system with "carb heat" that is used on airplane engines with carbureators. In airplanes the air must be heated because not only is there a temp drop because of the venturies but you are also evaporating fuel there which also lowers the temp (sometimes below freezing). On the Delorean the fuel isn't induced into the air stream until after the air sensor plate. The preheat system is only going to be active when it's cold and the engine is warming up unless it is extremely cold in which case it may stay on. It's only purpose is to help the car warm up quicker. Once the engine is warmed up the engine itself "preheats" the air as it enters the manifold before injecting fuel into the warmed air. If you are experiencing carb ice then the air is probably supersaturated below the dew point and close to freezing, an uncommon situation in most areas of the country (on the ground). This almost never happens on fuel injected engines anyway. I agree that the intake is restrictive but just tinkering with it alone won't do very much, what goes in must come out so if the exhaust is also restrictive it wil become the limiting factor. In fact you can gain more there because heated gases expand so the air going in needs more room to get out. The exhaust system must be oversized compared to the intake to accomplish this. Also it is usually not a great idea to combine the two cylinder head exhausts, they should be kept separate but it was done on the Delorean so there is only 1 catalytic converter. Back in hot-rodding days the first thing you would do after changing the tires was to put headers in because that gives the biggest bang for the buck and is necessary for all other improvements. --- In dmcnews@xxxx, jwit6@xxxx wrote: > Under the right conditions, temp and humidity, running without preheated air entering the intake tract can cause carb/throttle body ice build up. This may not be a common problem with Deloreans but has happened to me on other automobiles and is entirely possible on the D. The engineers knew this and although the Delorean doesn't have the restrictive venturi of a conventional carb, it's still capable of icing up. > > "dmc6960" <ultra@xxxx> wrote: > > >I must disagree with you on this John. You say the air valve is to > >keep water in the fuel system from freezing?