A big block Chevy weighes about 550 pounds to 700 pounds depending on casting and heads. This dose not include assesories, oil pan, fuel, or exhuast. Center of gravity is about 1.25 inches fore of block center. When installed in vehicle, another 250 to about 450 pounds in additional weight is added. Typical installation, about 400 pounds witch inturn pushed the c.g. forward about 6 inches fore of block center. Remeber that one cubic foot of steel or iron weights 490 pounds.