I have a "48" 3100 with a "55" 235. 1,000 since rebuild . The temp runs at 180 on the highway but in town will climb to 200 and higher if stop and go driving. I did not notice this in-town temp the first few hundred miles. I advanced the timing and adjusted the floats on the carbs to stop a gas leak and that is when I think it started running hot. I changed the timing back to where the ball is just in the window. This engine is so new to me it is hard to say what normal is. I have a short shaft water pump with original 4 blade fan. Space between radiator and fan is 1.25". The draft tube has been replaced with a PCV valve. Questions are:
1) If the engine was running lean causing higher temp would it also run higher on the highway.
2) Should I shim the radiator closer to the fan.
3) Could I just build a fan shroud to solve the problem.
4) Would a different fan blade help.
