[Hansfragger]

Hello everybody. I didn't like using a 90 degree elbow to route the tubing in and out of my radiator. I also didn't like the idea of coolant flowing into the radiator header tank, then making an abrupt 90 degree turn. To minimize this disruption to flow I decided to drill the end of the header tank and solder in place bung fittings. Trying to get the max flow in and out I wanted to use the least restrictive fittings. The DD 9/16-18 1/2" barbs are the most open I have come across. Here is where I ran into a problem. Most radiator inlet and outlet bungs are 1/4 NPT(some use 3/8 NPT). I started a thread asking for help in locating 9/16-18 bungs. No one knew any sources. All of the radiator shops I contacted only had 1/4 NPT and 1/8 NPT. So I decided to machine my own. Starting with 3/8 outside, 1/4 inside brass adapters I drilled out the center with a 33/64 bit, then ran a 9/16-18 tap through. Next I cut off the bulk of the length of the fitting so as little as possible would protrude into the header tank. I found that drilling the header tank turned out to be a real touchy operation. As I gradually increased the diameter of the drill bits at 1/2" the flutes on the bit started to rip and twist the thin copper of the header tank. I then took the rad to a large radiator shop in Nevada that said they were a full service facility and they weren't kidding. They said they could finish opening up the bung hole (I can see the flood of jokes coming now), by using a die grinder and then soldering the bung in place. They placed the rad in a hot chemical bath to remove the existing finish, ran it through the cleaning tank, then pressure tested it to 10 PSI. The guys at A-1 Radiator had a great "can do attitude". I then sprayed the exterior with a high-solids enamel. The fin area was left unpainted to ensure max heat transfer to air. I was willing to live with the funky look of the fins as the chemical bath only partially removed the factory finish. Here is a few photos along the way. I am making a few (hopefully for the better)modifications to the design of my external cooling unit and will post more pics when completed.