This nut was then drilled and re-tapped to accept a standard automotive type spark plug. Compressor bleed air, or shop air at startup, flows through the bearing cooling jacket, through an inline air tool lubricator, and then into the oil inlet on top of the bearing housing. The inline air tool lubricator deposits an adjustable amount of oil into this air stream, which is forced through the bearings. After passing through the bearings, this oil-air mixture is allowed to drain out of the bottom of the bearing housing through a rubber hose and is collected in a bucket. It was decided early on that in order to keep the project simple, this method of lubrication would be used versus a fully recirculating system encompassing a pump, filter, cooler, etc.
Oil consumption is a modest nine ozs.
In order to monitor engine performance, several pressures, temperatures, and air-flow need to be measured. Pressure indications on the fuel inlet, compressor discharge, and exhaust duct use small 0-60 psig gages from the local hardware outlet. These are the type normally used in air systems for air tools. Temperature indications for ambient, compressor discharge, turbine inlet, and turbine outlet, are accomplished using short sections of K-type thermocouple wire with the two conductors at the sensing end twisted together. The voltage generated by each element can then be measured with a multimeter, and compared to a chart in order to determine temperature.