Running hot, need bigger fan and other tricks advice please

[767Jockey]

Since you were all kind enough to chime in with your opinions on my running hot situation, I wanted to provide an update so someone searching the forum due to facing a similar issue in the future might get some info on their problem as well.

I removed the surge tank (again, it's a FE) and lo and behold, there WAS a thermostat in there. It's my first time in there, and the engine builder had said he hadn't put one in, so beats me how it got in there, but there it was. It was a standard thermostat, 180 degrees, with the usual 1/8" hole drilled into the top center of the thermostat mounting flange. I removed it anyway, and replaced it with a new 180 degree balanced thermostat, supposedly "high flow". No idea what that means with comparison to a regular thermostat, but that's whats in there now. I drilled two smaller holes into the top of the mounting flange instead of one big one. I forget the size bit I used, but the total area is slightly more than 1/8". I put the coolant mix back into the radiator, and added a bottle of Water Wetter as well. This next point I believe may be the key to the new success. In looking carefully at the fan and shroud, in an area that is hard to see, there was a gap around one side of the fan where it meets the shroud. It was about 1/4" to 3/8" wide and about 5" long. There were a couple of much smaller gaps where the shroud meets the radiator. I sealed all those gaps up.

I just took the car for a 30 minute ride around town. Stop and go, traffic lights, etc. It never got over 85 degrees C, which is about 185 degrees F. Couldn't be happier with that. My only reservation with declaring victory over this problem was that the day when it was running very hot, it was about 90 degrees outside. On this run it was about 72 outside. I'm not sure we will have another day at 90 or better, and if we do I might not be home to give it the hot day test before winter (such as it is in Houston) sets in. Given all that, I think I'm in much better shape now than what I was before I did all this. Next year will be the test when it gets hot outside again, but I'm hopefully optimistic that I may have a handle on this now.

Thanks to all of you for the suggestions. Now that I can actually drive it, I have more of the typical new build bugs to sort out. They'll be in separate posts here on the forum seeking your opinon on the best solution. Thanks again!