Abstract: A closed deck type cylinder block providing an optimum area ratio of opening at a top deck side, and a method for producing such cylinder block having the reduced area ratio of the opening at a reduced energy cost and with reduced labor, yet exhibiting smooth discharge of waste sand converted from a water jacket core through the opening in spite of the reduced area ratio of the opening. The cylinder block is formed with a plurality of cylinders juxtaposedly arranged to each other and a water jacket portion surrounding the cylinders. An upper end of the water jacket portion is open at a top deck and is partly covered with bridge portions. The opening has an area ratio of from 10 to 30% of a projection area of the water jacket portion at the top deck surface.

Abstract: A material for a mold which comprises, as main components, a refractory aggregate and a hardenable binder comprising a polyfunctional acrylamide having at least two ethylenically unsaturated groups in the molecule, has an excellent low-temperature rapid hardenability, disintegrability, and pot life and is especially suitable as a material for a mold for casting a low-melting-point metal such as an aluminum alloy.