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Engine Evaluation Test Group Components
1. 1P7443 Tachometer2. Tachometer Forward-Reverse Switch3. Tachometer Input4. Continuity Indicator5. Continuity Input6. 4S6997 Manifold Pressure Gauge7. Manifold Pressure Inputs8. 5P6579 Differential Pressure Gauge9. 5P6579 Differential Pressure Gauge10. Differential Pressure Inputs11. 1P7447 Pressure Gauge12. Psi Input13. 1P7444 Tachometer Generator14. 1P7445 Electric Tachometer Cable15. 1P7448 Mechanical Tachometer Cable16. 5P2948 Fittings17. 2A4716 Dust Caps18. 4K9822 Nuts19. 4K9821 Sleeves20. 1P7446 Rack Terminal Cable21. 4S8381 Tube (50 ft - order by the foot)22. 5P9693 Cable Ties23. 3K6675 Fittings24. Storage Container for FittingsTachometer
The 1P7443 Tachometer is a direct reading tachometer with a range of 0 - 4500 RPM. The tachometer scale indicates 1000 RPM for each revolution of its pointer, and multiples of 1000 RPM are shown in the window on the left of the dial face. The instrument is calibrated with a tachometer generator which produces a voltage relative to one-half engine speed. Tachometer accuracy in the following ranges is: 25 RPM @ 0 - 1200 RPM, 15 RPM @ 1200 - 2300 RPM, 25 RPM @ 2300 - 3000 RPM, and 40 RPM @ 3000 - 3500 RPM.The 7M6001 Tachometer Drive Adapter Group used on some 4.0" and 4.5" bore engines and some special tachometer drives runs at engine speed. On engines with this adapter group, the 5S6106 Adapter must be connected to the tachometer drive, and the tachometer generator connected to the adapter. This will reduce the generator speed to one-half engine speed and will prevent overspeeding of the tachometer.The 5S6106 Adapter and other tachometer adapters are shown in the TOOL GUIDE. A 5L2277 Tee Adapter can be used to check the accuracy of the machine tachometer against the 1P7443 Tachometer by allowing both tachometers to run at the same time. The outputs at the ends of the tee turn in opposite directions; therefore, a tachometer forward-reverse switch is used to accept either clockwise or counterclockwise rotation.Pressure Gauge
The 1P7447 Gauge is used to check the fuel delivery pressure on natural gas and diesel engines. This gauge has a range of 0 - 100 psi and an accuracy of 2 psi. If a different pressure range gauge is needed for special applications, use one of the gauges in the 5P6225 Hydraulic Test Box.Continuity Indicator
The continuity indicator is used to indicate governor balance point on engines equipped with a brass screw terminal on the governor housing. One lead of the rack terminal cable is clipped to this terminal, and the other lead is clipped to ground. When the rack stop collar just touches the torque spring, the light just barely comes on (a dim, flickering light). Power is received for the light from the tachometer generator so the indicator will not work unless the engine is running. CAUTION: Use the continuity indicator only while using the 4S6553 Test Group because a battery powered indicator might interfere with the tachometer generator voltage and cause incorrect tachometer readings.Manifold Pressure Gauge
The 4S6997 Gauge is a duplex manifold pressure gauge with a range of 15 to 100 inches of mercury (Hg) absolute and an accuracy of 1.8 inches of mercury. The gauge reads absolute pressure. This is barometric pressure plus the boost from the turbocharger. The use of an absolute pressure gauge simplifies the test procedure on some engines and provides a barometric pressure reading without requiring an additional gauge. The duplex gauge permits reading two pressures, such as both banks of a V-type engine, or for comparing manifold pressures between two engines carrying a common load. If only one pressure tap is required, the other needle of the gauge provides a continuous barometric pressure. The connections to the gauge are made at the manifold pressure inputs shown on page 2. The fittings are marked to indicate which gauge needle will be connected.Differential Pressure Gauges
The differential pressure gauges read the difference between two pressures. They have a range of 0 to 50 inches of water and are accurate within 1.0 inches of water. The gauges have two inlet ports - one for the higher pressure and the other for the lower of the two pressures. The gauge will then indicate the difference between the two pressures. If one port is left open to the atmosphere, the gauge can be used to measure the difference between atmospheric pressure and the test pressure. If the high pressure port is connected and the low pressure port left open, the gauge can be used to read a positive pressure, such as the exhaust back pressure due to a muffler. By connecting the low pressure port and leaving the high pressure port open to the atmosphere, a vacuum can be read, such as the inlet restriction through an air cleaner. If both ports are connected to positive pressures, such as the gas delivery pressure and inlet manifold pressure of a turbocharged natural gas engine, the gauge will read the difference between the two pressures.Two differential pressure gauges also permit simultaneous reading of both inlet restriction and exhaust back pressure when road testing vehicle engines. The gauges and inputs are identified by the letters DP1 and DP2 stamped beside each gauge and the appropriate inputs as shown on page 2. Each input is also identified by the letter "H" or "L" stamped near the input to identify the high and low pressure connections.Each gauge has a zero adjusting screw. When necessary, adjust the screw so the gauge reads zero with no connections to the gauge fittings.Maintenance Of The 4S6553 Engine Evaluation Test Group
(A) Cleaning The 4S6997 Manifold Pressure Gauge
If duplex pointers (1) do not lie directly on top of each other when the gauge is open to atmospheric pressure at both ports, the gauge may need to be cleaned. Remove the gauge from the test box. Remove elbows (2) and slotted needles (3). Clean the slots in needles (3) with a piece of fine wire. Install the two needles and elbows.If the pointers still do not lie directly on top of each other, return the gauge to the manufacturer for repair. See