360 is still running hot

I finally got the car out on its maiden voyage today! It was a long winter and lots of hours putting in new parts and goodies. Which included a nice set of Speedhut gauges.

One of the issues I was having prior to the end of last year was the car overheating. I picked up a 3 row Champion Radiator to help cool it down. Im also running twin 10" Perma-cool electric fans that they claim move 2800cfm each.

Just a FYI prior to this 360 I had a 318 that ran nice and cool. Right around 180* with a old nasty radiator. The 360 did not like that radiator at all. I know the engine got up to 250* at one point last summer.

To help the cooling issues I also installed a 160* t-stat, which I verified opened before I put it in. The electric fans are suppose to kick in at 185 and off at 165 (if I remember correctly). I also have a 6 blade water pump.

Before I took it on a drive I let it warm up to verify the fans would start and no leaks etc.. They actually didnt kick in until close to 200*. I figure I could deal with that discrepancy and take it out. As I was driving it just kept creeping up. The first run was about 6 miles. When I got home the gauge was at 212*. I let it cool down. Checked some more things and then the future wife wanted to go for a nice drive today. So we took it out for about a 35 miles drive. It stayed at 212* for about half the drive, then crept up to about 220*. Its a cooler day, about 68-70* when we took it for a drive, but come mid summer heat there is no way it will stay cool.

The motor only has around 600 miles on it so its a fairly fresh build. Although when I changed the t-stat I noticed there was a lot of gunk around it. Kinda a brown slime to say. I wouldnt think that the engine shop would send out a fresh engine with stop leak still in it but it came to mind. Im just at a loss as to what to change or try. Other than change to maybe a 8 blade water pump or something high flow. Please help me try to figure this out..

O