Been there done that! - very satisfied. In 2003 I installed two 14" Permacool fans to my 81 Chevy truck with 350 cu.in turbo 400. I eliminated the mechanical fan. Do not mount the fans with the enclosed mounting hardware through the fins. In one year they will cause the radiator to leak from the starting torque of the fans. Buy ( from Lowes ) a sheet of aluminum 3/16" thick and big enough to span across the rear of the radiator. Trim the aluminum to fit perfectly over the back of the radiator. Mark and drill the aluminum using 2" bolts and nuts to mount it on the top and bottom radiator frame ( offset plate about 1/2" behind radiator ). Remove plate, lay out on workbench, and place fans for maximum coverage ( low on drivers side, high on pass side ). Mark, and cut out holes for fans. and mount ( Use washers and threadlock to prevent vibrations ). Run hot wires to the fans to insure proper rotation. Once the aluminum plate with the attached fans are mounted securly check to make sure adequate clearance. FYI each of these fans draws 2950 cfm. A 350 engine requires about 4000cfm to keep its cool. Connect an adjustable radiator fan switch ( Jegs # 400-31147) using two heavy duty 30A relays. I used an inline 30A circuit breaker that works independent ( hot all the time ) of the ignition switch. That means when I shut off my engine sometimes the fans come on for 5 min then cycle off. This system has worked flawless for 5 years. With trial and error I have adjusted the fans to come on at 210 - 215 and off at 190. The hotter the cooling system runs the more thermally efficient the engine becomes. Plus better fuel economy. It's satisfing when you hear the fans come on and you can see the temp guage going down then the fans turn off. The less the fans turn on the less horsepower is used ( by the alternator ).
