Trap Door Inside Exaust Manifold

I operate a lil differently.... I installed an electric choke and I have headers so there is no back pressure to keep the heat AND if it isn't at least 65 and sunny, my classics don't leave the garage. Also, being raised in Detroit and around cars my entire life, it is kind of a given that you do not "get on it" when everything is COLD.....thats just being DUMB!
As far as the heat risers are concerned I make a point of removing them and pluggin the holes, they are nothing more than a chronic hassle, they malfunction they get stuck closed and they are NOT reliable in the least. I typically dont disagree with Dan, he is quite knowledgeable but in this case once the motor is up to operating temp, it is well past the temp to vaporize gasoline, hence the hassle and problems associated with the riser out weigh the efficiencies realized with the riser. I know quite a few registered master mechanics in the Detroit area and not one of them appreciates the minor benefits of the heat riser, in fact they are widely despised here in Michigan. It is rare to see one intact on most classics in and around Detroit. I will not disagree that there are benefits, especially if you drive in cooler to cold weather. BUT the benefits are seriously out weighed by the hassle and most folks round here don't use their classics as "dailys" esp in the winter months. I guess the point is removing them is not a critical threat MHO