Truck Overheating ?????

[69Custom]

Ok, I now have a problem with my rebuilt engine. It is a rebuilt 350, bored 40 over, 400 small block heads, mild cam, and roller rockers. I put a rebuilt water pump on it and a new thermostat. It started to over heat after having the engine in for about three weeks. I replaced the thermostat with a high performance one (both are 190 degree). I am also using that new antifreeze, 150k mile stuff. I also lost my control of my heater. When I got to work today it was overheating off and on, and at lunch time I didnt have to go far, but it almost stayed at 260 the whole time. I open the hood with the truck running and felt the hoses. The ones going into the firewall were cold, the top hose from the thermostat was really hot and the lower one that goes into the water pump was somewhat hot. Can any one give me a clue to what is happening?

Thanks in advance

Jerr

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New Project

• 72 Blazer 4WD 307/3 spd, PS, PB, Posi (Current Project)
• 83 Chevy SWB Rebuit 350/TH-350 with shift kit, buckets (daily driver)