[Sirrotica]

The only time I've blocked the heat crossovers, is in a dedicated race car that saw zero street duty. The convenience of having it operational, far outweighs the reasons to block it. I guess if you want to keep feathering the gas until the intake warms from the rest of the heat transfer from the cylinder heads, that's your prerogative, to me it's an annoyance. Yes I have done it years ago on my own vehicles, the juice, wasn't worth the squeeze, IMO.

I set my carb and choke adjustments so that the car runs the same as if it was fuel injected. No stumble, or flat spots during warmup. I however takes a bit of work, and attention to detail for a carb to run like this, everything has to be 100% correct, no guessing. You must adhere to all the choke adjustments, or you'll never achieve the smooth running engine during warmup.

Even GM used heat from either the exhaust, or from the coolant, to work in conjunction with TBI, or tuned port injection.

The talk about a water laden air fuel charge causing ice inside of a intake is not idle talk. When I attended my high school auto mechanics class our instructor told us about a friend of his that hand built a intake manifold from tubing for an inline GMC 6 cylinder to adapt 3 carbs to it. He said that when the humidity was high, and the air temp was low, the car wouldn't run right. like it was starving for fuel, or air. One night it got to the point that it would barely run, and they unbolted the carb from the manifold. Imagine the owners surprise when he looked into the manifold, and saw the tubing had ice formed in the inside of the manifold.....

They found some 12 volt heat tape to use to heat the manifold for when the temps and humidity got to the crucial point to cause ice to form in the intake, problem solved.

Having to keep feathering the gas during warmup also makes the accelerator pump dump a lot of excess fuel into the manifold to cover for lack of heat. That excess fuel is washing the oil from the cylinder walls and causing the oil to be diluted, as well as increasing ring, and cylinder wall wear. For a race engine this isn't going to be a huge problem, for a street car it's going to show up with fuel dilution, and premature wear.

To me, not worth the tradeoff for some slight possible performance gain.

Your car, and your choice.