I know this is a topic that has been discussed many times but since I still have the problem I thought I would ask again. i have a 67 GTO, 400, no ram air, quadra jet carb, 73 heads with cross over blocked off. As long as I'm moving it runs at 190 degrees. As soon as I stop for traffic it runs up to 230 degrees. What I did so far. New "desert cooler rad from Ames, new high volume water pump, new clutch fan, new shroud, new 160 thermostat, seven blade fan, new 15 lb rad cap. What's left? I've read about the space between water pump inpeller and diverter plate not being correct. What should that space be? How could it have changed? How do I ajust the space? Some other info, timing seems good. Checked it with a timing light. Starts fast, runs good . No ping, no milky oil like a blown gasket. I'm stumped. Any help would be greatly appreciated.