THERMOSTATIC AIR CLEANER (THERMAC) - The air cleaner is design to provide an incoming air temperature of about 115 degrees (F). A temperature sensor is in the carburetor elbow and is used to control a vacuum actuated damper door in the snorkel of the air box. This door on the snorkel blends incoming air with air heated by the right side exhaust manifold, via a very narrow duct. This improves winter weather driveability. Warmer climate and summer only driven vehicles can do without thus system. During WOT acceleration, the (carburetor) vacuum drops to zero and the door will slowly open to allow unblended air through the snorkel alone. There is an inline delay valve which could be remove for quicker opening of the damper door.