Engines:  The 165hp 305 V8 with a 4-speed became the standard Z-28 power combination for 1981, with the optional 350 reduced to 175 hp and available with THM-350 auto trans only.  There were no 4-speed with 350 engine combinations produced for the US market.  However, Canadians could still order the 350 engine (non-CCC), with a 4 speed manual transmission in 1981.  All US engines were equipped with CCC emissions control.  The automatic transmission in the Z28 came equipped with a lockup torque converter which locks in 2nd and 3rd gear.  This was introduced as a gas savings measure.  Both the 305 v8 and 350 V8 came with the Rochester Quadrajet carburetor.  Standard size Z-28 tires were P225/70R15 on 15x7 wheels.  See wheel and tire section for more information.