Is there a motor bigger than a 427?

Yes, chevrolet's largest V8 in a production car was the 454. Much bigger can be built with aftermarket parts 502,565,632 or even bigger with the 4.9-5.0" bore space blocks, like 700+ cubic inches. If you mean only from the factory, other makes had bigger factory motors, biggest was Cadillac, they introduced a 500" V8 in 1970.