I have a 72 convertible cougar and I have gone through and rebuilt the 351 Cleveland and now it constantly overheats. I had to bore the block 30 over. I went with a set of keith Black hyperutectic pistons and have a stock set of reman heads. The car is just for cruising and car show hopping so I built it keeping in mind the 4 dollars a gallon for gas. All the internals are pretty much stock specs so I can not understand why it wont stop overheating. I have tried electric fan(s), clutch and no clutch fans of all sorts of blade counts widths etc. I have a brand new aluminum radiator. I am running a 185 thermostat currently and have gone clear down to 160 with no change. The restrictor plate inside the thermostat area is there as well. If anyone can help or come up with any ideas that could help I would really appreciate it. By the way the car is running in an upwards of 230 degrees Fahrenheit. This will happen on a 70 degree day while in light stop light traffic.