The pilot reported that climbing through 550 feet agl, the engine lost power. He lowered the nose of the airplane, established a glide, checked the engine controls and fuel selector, and pulled the carburetor heat control to no avail. At one point, ‘the engine started but would run at a fast idle, and for only a few seconds.’ he conducted a forced landing in a soybean field. Examination of the wreckage revealed no anomalies. During a test in a production test cell, the engine operated normally and produced maximum rated power.