90653-HC4-900 Honda CLIP, SPLASH GUARD (Honda Code 3795994).

Introduction
The 8T5250 Engine Timing Indicator is a test instrument that can be used to measure fuel injection timing for a diesel engine, or spark plug firing on spark ignition engines, while the engine is in operation. The timing indicator can also be used to check the operation of the automatic timing advance unit, on engines that are so equipped.Electrical power to operate the unit comes either from the vehicle electrical system, or, if there is no electrical system available, from two 6 volt lantern-type batteries. The 8T5300 Engine Timing Indicator Group must be used with an 8T5301 Diesel Timing Adapter Group on a diesel engine, or, a 6V9060 Spark Timing Adapter Group on spark ignition engines.In the 8T5300 Engine Timing Indicator Group, the fuel line transducer connects to the fuel injection pump bonnet of No. 1 cylinder, and is then connected to the engine timing indicator. The fuel line transducer can then send a signal to the 8T5250 Engine Timing Indicator when fuel is injected into No. 1 cylinder.For spark ignition engines, a spark transducer connects to the primary coil for No. 1 spark plug, and sends a signal to the 8T5250 Engine Timing Indicator when the spark plug fires.Most current production Caterpillar diesel engines are equipped with a static timing pin hole in the flywheel housing, and a corresponding hole in the flywheel. When the two holes are in alignment, the piston for No. 1 cylinder is at top center position. A bolt can then be put through the hole in the flywheel housing and threaded into the hole in the flywheel to lock the engine at the top center (TC) position for static timing.For dynamic timing, an adapter and a TDC magnetic transducer are installed in the flywheel housing timing pin hole (see the installation procedure in this instruction). When the transducer is connected to the 8T5250 Engine Timing Indicator, it sets up a constant magnetic field around the end of the transducer and the flywheel.As the flywheel turns (engine running) and the timing hole in the flywheel passes the end of the transducer, a change in the magnetic field causes the transducer to send the TC signal to the 8T5250 Engine Timing Indicator.In diesel engine operation, fuel is injected before No. 1 piston reaches top center position. In spark ignition engine operation, the No. 1 spark plug fires before No. 1 piston reaches top center.The 8T5250 Engine Timing Indicator receives the fuel injection, or spark, signal first, then measures the time it takes to receive the top center (TC) signal. The timing indicator then converts these two signals, and the time between them into engine rpm, and engine timing in degrees before top center (BTC). After the 8T5250 Engine Timing Indicator receives the fuel injection or spark signal, the first signal that the magnetic transducer sends will be considered the No. 1 cylinder top center signal. It is then, important for the flywheel to be free of any other holes or large nicks between the point of injection (or spark plug firing) and top center (TC).As an example, if the specifications indicate that fuel should be injected into No. 1 cylinder @ 15° before top center, the flywheel must be free of holes or large nicks in the area of the flywheel that is at least 15° before top center (BTC).For correct operation, the timing indicator must receive the TDC signal within 60° flywheel rotation after it receives the fuel injection signal, or, the spark signal. If timing is actually after top center, i.e., the TC signal occurs before the injection pulse, the timing indication will be incorrect, and be a steady number between 60° and 90°.Glossary
TC: Top Center.RPM (rpm): Revolutions Per Minute.°BTC: Degrees Before Top Center.DEG: Degrees.Features (characteristics) of the 8T5300 Engine Timing Indicator Group
Adaptability:This timing indicator group is usable on engines that have a TDC bolt hole in the flywheel housing, as found on 3300 and 3400 Family Engines, and on 3500 Family Spark Ignited Engines. It can also be used on 1100, 3100 and 3208 Family Engines that have a timing hole in the engine front cover.All other Caterpillar (non-unit injector) engines can be timed with the 8T5300 Engine Timing Indicator Group, if the engine is modified to permit a way to get a TDC signal. Accuracy:The timing indicator group can be used, and has the accuracy, to check the dynamic (engine running) timing of the entire fuel system. It can also be used to check the operation of the timing advance mechanism, on those engines that are so equipped. Operation:There are no restrictions on engine speed or load, so timing can be checked during the actual operation of an engine. The digital readouts (number indications) are liquid crystal displays (LCD) that have long life and high accuracy. Fuel System Connection:A fuel line injection transducer "tee" adapter is installed in the injection line, AT THE FUEL PUMP. The injection line will be moved only about 8 mm (.3"), which will keep bending of fuel lines to a minimum. Installation time is also held to a minimum. DO NOT ATTEMPT TO USE THE 6V4950 FUEL LINE SPEED PICKUP. IT IS NOT DESIGNED FOR THIS APPLICATION. Timing Indicator Connection:The connecting cables for the timing indicator group are 18 feet (6 m) long. If necessary, the serviceman can have the timing indicator connected and read it in the operator's station. All electrical connections can be connected in only one way, the correct way. Power Supply:The vehicle electrical system, (12V, 24V or 32V) either positive or negative ground, is the source of power for the timing indicator group. There are no internal batteries. For those engines that do not have an electrical system for a power supply, two 6 Volt lantern-type batteries, wired in series, can be used as a power supply for the timing indicator group. Troubleshooting:The design of the timing indicator group is such that any problem with the operation of the unit can be found quickly and easily, whether the problem is with