i have a '96 F350 Dually with a 7.5L that i rebuilt and i have an issue with it. it runs too warm. it has a new cam that is slightly larger than factory. nothing major, just an improvement on low end torque. the crank was turned, rods were trued, new pistons and rings .030 over. i installed reman factory heads with comp cam valve springs installed. i took the bare engine block to a shop to have it cleaned. the block was stood up on a turntable and a 4 nozzle pressure washer washed the block for some specified amount of time. i did not know till the engine was inside my truck and was having issues that they didnt put it in acid or whatever it is called. my dad called it acid but i dont know. im not sure what the technical term is, but when i had the engine on the stand and was building it, i noticed that there was white chunks of a rock substance inside the water jackets. i broke it out as much as i could and kept turning the engine block upside down to dump it out, but im not sure if there is anything else in there. i installed the completed engine that i spent around $5500.00 on and burned in the cam according to the instructions from comp cams. since i built and installed the engine, it has ran too warm. not to the point of overheating, but that is because i would not allow it to over heat. everything on it is brand new i mean as far as water pump and stuff. in diagnosing this issue, the shop that i had clean the block and install the rotating assembly asked if i had installed a head gasket backwards. i told them no, but they made me doubt myself, so i removed the heads. both gaskets were indeed on correctly. the next thing was the backing plate on the water pump. it is visible so it is easy to see that i did not forget to install it. next was to replace the radiator. it had a 2 core that was less than a year old, but i installed a solid aluminum 3 core radiator with 2 electric fans that sound like a tornado under the hood. it didnt change anything. oh, also i have installed 3 different brand new motorcraft 192 degree thermostats as well. i set the timing to 10 degrees BTDC with the lug unplugged and verified the timing multiple times. i tested the coolant system to see if there was any combustion gases present, and there was not. that is everything that i can think of. i am starting to think that i should remove the engine and take it down to the block and find a place that will submerge it in acid to clean the water jackets, but i dont know. im not sure what to do at this point. any suggestions would be welcome. i enjoyed driving that truck and do miss it. thanks for any suggestions.