Big Cam Cummins problems

Hello all! First post here. I'm having some problems with a Big Cam II that I need some advice on. First, some history. My customer has an old water well drill rig that runs a Big Cam 400. A few years ago, the engine went out and rather than rebuild it, he bought a truck cheap with a running Big Cam that the guy claimed was pushing 480 horse. We put the engine in the drill rig which required swapping injection pumps to work with the rear controls on the rig. The engine ran great, but temp would always climb when running the massive air compressor to blow wells. Over the course of an hour the temp would climb to 220 plus (and they never informed me of the problem). Well, they weren't paying attention, thermostat stuck, and piston 1 grabbed and broke cylinder 1 sleeve, and clunk... it locked solid. Well, the customer is looking to have his rig repowered in the not to distant future to meet ridiculous California regulations, so he wanted the engine patched up for the time being. I tore it down, replaced number 1 piston and sleeve, deglazed and reringed the other five cylinders, and replaced all the bearings as they were in sad shape. Put everything back together with a new thermostat and water pump and it sounds beautiful and has great low-end torque, but falls on its face running the compressor and temps are climbing much faster-210 in 10 minutes under full load. Some specs on the engine. It is CPL 393 which is 14.5 to 1 compression. However, it has cam part number 3000850 and injector part number 3047973 in it which do not match that CPL. I'm not sure what timing is set at, I put it back together with the same thickness gasket as came apart. Injection pump is number 0310, I think. This engine NEVER smokes, even when coming up on power when engaging the compressor. The customers said all previous engines would belch when rolling into power. I'm going to see if I can swap buttons with the pump that originally came off this engine. However, I'm looking for advice for what else to check. Thank you!

 

Update for everybody. First, thank you for the replies! I understand what you are saying about the engine not being built for a constant load. However, rebuilding this engine to a different CPL is not within my customer's budget, especially because it will eventually be getting repowered after he gets some other equipment and his other rig repowered. I swapped buttons in the pump with what was on the engine initially, and it is now putting out the needed power with healthy EGTs. The radiator was only cooling 15 degrees between top and bottom, so will be pulling the top tank tomorrow to see what's going on there.

 

The fins on the radiator are clean and the fan pulls air. The fan is moving a lot of air, so I don't think that is our problem.