Abstract: The intake fuel charge of an internal combustion engine is heated by utilizing the heat from the exhaust gases which are controlled by a valve mounted on a shaft having a counterweight secured to the shaft to control rotation thereof. A stopper which is engaged by the counterweight is provided for limiting the extent of rotation of the shaft and a spiral bimetallic member is arranged with its inner end secured to the shaft and with its outer end adapted to engage the stopper during engine warm up at relatively low ambient temperature conditions. An engagement member is mounted on the bimetallic member to engage the stopper when the second end of the bimetallic member moves in the direction opposite the direction whereby it would normally engage the stopper. The engagement member may be mounted a distance spaced from the outer end or it may be secured in back-to-back relationship with a second stopper member being provided.