Do not let malfunctioning piston jets cause engines to sump or overheat, test them before you install them. Located deep inside the engine cases it is hard to verify whether these piston jets are functioning properly. Not any longer as this Jims piston jet test stand allows engine builders to test them for proper operation before installing them. The unit operates on both compressed air, and air over oil. When operating with air only, verification of proper flow through the piston jet can be witnessed. In the air over oil mode you can not only check for proper operation, but also physically see the oil spray pattern emanating from the jet. By adjusting the air regulator on the unit, mechanics are able to determine at what pressure the piston jet turns on and off. An additional benefit of the piston jet test stand is the ability to clear assembly lube from the jet's narrow oil passage.