American Motors: 1966 AMC Marlin, degree thermostat, fan shroud


Question
The engine and radiator has been redone totally, while cruising, the temperature is about half or below, but when I hit traffic, after a while, it starts to go up the 3/4 or so way. The radiator was converted to a 3 core and I have a fan shroud with a 6 blade fan on it. I can't fit a 7 blade with the fan clutch, due to no space to install it, what is your opinion. The engine is about 1k miles into it.
Thanks,
Bert.

Answer
Here are a few things to check:
1) Are you using a 160 or 180 degree thermostat?
2) Is the water pump new? Leave the radiator cap off while the engine is warming up. Be sure the coolant is circulating strongly.
3) If you have a fan clutch, it could be slipping at lower engine speeds. This would slow the fan speed down.
4) Can you depend on the accuracy of your temperature gauge? You might want to hook up an auxillary temp gauge to get an actual tempuerature reading.
5) Use you hand and CARFULLY touch the front of the radiator at idle. It should feel uniformly hot all around the surface. If you feel cool or cold spots, your radiator might be restricted.
6) Is your ignition timing properly set? An overly advanced timing can increase engine temperature.
Uness you can get an actual coolant temperature, you don't really know if your engine is overheating. It should probably not get over 185-190 degrees.
Hope this helps.
Kevin