SECTION 4.10 IGNITION SYSTEM MAINTENANCE IGNITION SYSTEM MAINTENANCE

Transcription

1 SECTION 4.10 IGNITION SYSTEM MAINTENANCE IGNITION SYSTEM MAINTENANCE Inspect and test ignition coils once each year. Remove all oil, grease and dirt from the ignition coils. Pay particular attention to the area around the primary terminals. Thoroughly clean the ignition coil contacts. Use a soft brass wire brush if corrosion or an accumulation of dirt is present. Inspect the contacts for damage (see Figure ). The ground wires on each bank must be clean and firmly attached to the manifold(s). HALL-EFFECT PICKUP CEC IGNITION MODULE The Hall-effect pickup is located on the front gear cover. The pickup senses each magnet as it passes and trips the logic circuit of the Custom Engine Control (CEC) Ignition Module to fire (see Figure and Figure ). HALL-EFFECT PICKUP Figure F18/H24 Hall-effect Pickup Location GROUND WIRE Figure Ignition Coil And Harness HALL-EFFECT PICKUP Figure L36/P48 Hall-effect Pickup Location FORM 6284 Third Edition

2 CEC TIMING MAGNET CLEANING AND INSPECTION Magnetic Timing Disc The F18/H24 magnetic timing disc is located under a cover in the front gear housing, attached to the cam gear (see Figure ). Trigger magnets for the Halleffect pickup are permanently mounted on the disc. TIMING DISC MAGNETS Figure F18/H24 CEC Timing Disc Timing Magnets The L36/48 CEC ignition timing magnets in the cam shaft gear are accessed after removing the cover plate from the rear gear housing or mag drive housing (CEC generator equipped) (see Figure ). Once a year remove the cover plate and clean the timing magnets of any ferrous materials. Clean and readjust the Halleffect pickup gap at the same time. HALL-EFFECT PICKUP INSTALLATION To set the air gap specification, complete the following steps. 1. Install the Hall-effect pickup into the gear housing. 2. Thread the Hall-effect pickup clockwise until the pickup touches the timing disc. 3. Scribe a reference mark on the Hall-effect pickup and at the same point mark the rear gear housing. 4. Using the reference mark on the pickup as the starting point, rotate the Hall-effect pickup 3/4 of a turn (± 1/16 of a turn) counterclockwise to set the pickup to timing disc clearance. 5. After the clearance is set, snug the locking nut. IGNITION MODULE SWITCH SETTINGS When replacing the CEC Ignition Module, the new module requires setting a selector switch. The Ignition Module has a three position selector switch for setting the engine model (see Figure and Table ). The selector switch is a three position switch (A, B, and C). The selector switch must be set during Ignition Module timing adjustments. Use your finger or a screwdriver to switch to the proper application. NOTE: The Ignition Module is shipped from Waukesha Engine with the selector switch in the B (No Application) setting. Refer to Table for selector switch settings. SELECTOR SWITCH TIMING DISC MAGNETS Figure Previous Ignition Module Selector Switch Figure L36/P48 CEC Ignition Timing Magnets FORM 6284 Third Edition

3 SELECTOR SWITCH Figure Current Ignition Module Selector Switch 6. Remove cover from selector switch or access hole located on Ignition Module (see Figure and Figure ). NOTE: Current selector switches use a rotary switch. Use a screwdriver to align the slot in the correct position. 7. Set appropriate timing application by adjusting selector switch (see Table and Figure ). Table Ignition Module Selector Switch Settings SWITCH POSITION A IGNITION MODULE SERIAL NUMBER 811A 6 & 8 CYLINDER ENGINES 6 Cylinder VGF/VHP 1211A 12 CYLINDER ENGINES 12 Cylinder VGF/VHP 1611A 16 CYLINDER ENGINES 16 Cylinder VGF/VHP B No Application No Application No Application C 8 Cylinder VGF/ATGL 12 Cylinder ATG 16 Cylinder ATGL SPARK PLUG REMOVAL STANDARD IGNITION 1. Remove rubber recess cover from spark plug carrier bore. Do not pull on the CAUTION spark plug cables to remove the spark plug connectors. Pulling on the cable may loosen or detach the terminal connection within the Teflon tube. Disregarding this information could result in product damage and/or personal injury. 2. Hold Teflon tube and remove spark plug connector from spark plug tube (see Figure ). A B C C B A Figure Spark Plug Extension 3. Use Tool P/N to hold upper spark plug tube when removing spark plug (see Figure ). A B C Figure CEC Ignition Module Selector Switches 8. Replace cover over selector switch (current) or access hole (previous). FORM 6284 Third Edition

4 SHIELDED IGNITION COIL P/N 69694G HEX HEAD SCREW P/N TENSION WASHER P/N FLANGED ROCKER ARM COVER P/N A300139F Figure Spark Plug Tube Tool P/N SPARK PLUG REMOVAL CSA SHIELDED IGNITION 1. Disconnect primary shielded lead from CSA approved shielded ignition coil (see Figure ). P/N P/N G ROCKER COVER ACCESS TUBE P/N F PRIMARY SHIELDED LEAD P/N Figure CSA Shielded Ignition Coil Do not use the ignition CAUTION coil as a handle to lift the rocker cover. The coil can be damaged. Always remove the coil and spark plug extension before removing the rocker cover. EXTENSION P/N A211357X BOOT SPARK PLUG HOLDER 2. Remove three M8 capscrews and lock washers from coil flange (see Figure ). Use hand pressure to lift coil from rocker cover. Figure CSA Shielded Ignition Assembly FORM 6284 Third Edition

5 3. Pull extension from spark plug. Spark plug extension puller (P/N ) allows easy removal of spark plug extensions from cylinder heads (see Figure ). P/N G ROCKER COVER ACCESS TUBE P/N F P/N Figure Spark Plug Extension Puller Pliers P/N SPARK PLUG INSTALLATION CSA SHIELDED IGNITION 1. Install correct spark plug for application: P/N for G, GL, GLD engines P/N 60999S for GSID engines 2. Apply Parker Super O-Lube and install O-rings onto new rocker cover access tube (see Figure ). 3. Install access tube in spark plug holder. Figure Spark Plug Extension SPARK PLUG HOLDER 4. Liberally coat inside surface of boot located on extension with a high performance fluorinated grease such as KRYTOX GPL-206 (P/N ) or equivalent (see Figure ). 5. Install extension onto spark plug. FORM 6284 Third Edition

6 GREASE SCREW P/N (3 PER COIL) LOCK WASHER P/N (3 PER COIL) P/N P/N CONNECTOR BOOT GREASE Figure Spark Plug Extension Ignition coils that are CAUTION improperly grounded can cause misfiring. Make sure CSA coils are installed using three M8 x 20 mm hex head screws that are properly tightened. Disregarding this information could result in product damage and/or personal injury. 6. Install coil (P/N 69694G) and O-ring (P/N ) (see Figure ). Secure with M8 x 20 screws and tension washers. Install coils so keyway of coil connector will easily mate with individual leads. Tighten three hex head screws (P/N ) to N m ( in-lb). 7. Connect primary shielded lead onto coil. Figure Spark Plug Extension CSA SHIELDED IGNITION SYSTEM MAINTENANCE Spark plugs, boots, Teflon connectors, and coils must be properly maintained to preserve electrical integrity. The spark plug extension consists of a silicone O-ring (P/N ), a red high temperature silicone rubber boot (P/N ) and a white Teflon extension. Whenever service is required on the ignition system, the boot and the O-ring should be inspected for damage and replaced if damage is observed. Use KRYTOX GPL-206 CAUTION grease (P/N ) or equivalent between the boot ID and the spark plug insulator. This grease will assist in releasing the boot (P/N ) from the plug. Boot damage will occur if the boot is not greased. Damaged boots will allow flashover and shorten spark plug life. NOTE: KRYTOX GPL-206 (P/N ) is a higher temperature fluorinated grease manufactured by Miller-Stephenson Chemical Co., Inc. For technical information on KRYTOX GPL-206 call: (8 4 Eastern Time) or in Canada (8 4 Eastern Time) FORM 6284 Third Edition

7 The spark plug extension consists of a silicone O-ring, a red high temperature silicone rubber boot and a white Teflon extension. The current spark plug CAUTION connectors include the connector, an O-ring and a high temperature boot. Damage to the boot and the O-ring occurs due to the extreme heat in the spark plug well. Waukesha Service Operations recommends replacement of the boot and O-ring every six months to prevent damage to the components and/or possible personal injury. Inspect the boot for damage and replace if necessary. The boot (P/N ) should be replaced every six months. The extension contact and spring should work freely and be cleaned of all corrosion. Inspect the extension O-ring for cracking or other damage. The O-ring (P/N ) should be replaced every six months. Grease the boot to spark plug interface and the O-ring and extension at the coil socket with KRYTOX GPL-206 grease (P/N ). Although the boot will adhere to the plug in most cases, KRYTOX GPL-206 (P/N ) will aid in its removal without damage. Lower temperature silicone greases will not prevent sticking. Spark plug socket (P/N ) will fit over the boot if it adheres to the plug. Use KRYTOX GPL-206 CAUTION grease (P/N ) or equivalent between the boot ID and the spark plug insulator. This grease will assist in releasing the boot from the plug. Boot damage will occur if the boot is not greased. Damaged boots will allow flashover and will shorten spark plug life. Use of a new higher temperature fluorinated grease KRYTOX GPL-206 (P/N ) is recommended. This grease is non-flammable, non-toxic, non-migrating, and contains no chlorine, silicones or chlorofluorocarbons. The performance of KRYTOX GPL-206 is known to extend the service life of components (see Figure ). IGNITION COILS Ignition coils should be inspected and tested once each year. If a defective coil is suspected, test by replacing the ignition coil with one that is known to be good. Remove all oil, grease and dirt from the ignition coils. Pay particular attention to the area around the primary terminals. Thoroughly clean the ignition coil contacts. Use a soft brass wire brush if corrosion or an accumulation of dirt is present. Inspect the contacts for damage (see Figure ). CONTACTS CONTACTS Figure CSA Flange Mounted Coil Carefully inspect the ignition coils for cracks or other damage and replace if necessary. Always replace the coil O-ring with a new O-ring whenever the coil is removed. Always check the ignition coils with reliable test equipment. Replace the coil if its serviceability is in doubt. To help seal out moisture and prevent corrosion, use KRYTOX GPL-206 (P/N ) on the high tension connectors between the coils and the spark plug connectors. Always inspect the wiring harness and connectors for moisture, corrosion, cracks or dirt that can cause a short to ground. NOTE: It is recommended that all three coil mounting capscrews be secured to prevent premature failure of ignition coils. Properly maintaining all the major components in the system will preserve electrical integrity and prevent down time as well as damage to components. APPLY KRYTOX GPL-206 GREASE (P/N ) OR EQUIVALENT Figure Apply KRYTOX GPL-206 Grease (P/N ) FORM 6284 Third Edition

8 SHIELDED IGNITION TIMING 1. CSA shielded ignition systems are timed by opening the junction box for the #1 cylinder primary lead (see Figure ). #1 CYLINDER JUNCTION BOX Figure Typical CSA Shielded Ignition System 2. Install an inductive timing light around the wire labeled A (see Figure ). SPARK PLUG SPECIFICATIONS Spark plug information and torques are for standard and hazardous location ignition systems. Waukesha Engine recommends dry spark plug installation. 1. Clean and regap the spark plugs every 720 hours, sooner as required. Replace the spark plugs every 1440 hours or as required (see Table ). Tighten the spark plugs to the proper torque without lubrication. Whenever a spark plug is removed, replace the spark plug gasket. See Table for the specifications and part numbers. When regapping spark plugs, examine each spark plug for cracked porcelain, leakage and burned electrodes. Examine the spark plug firing end for abnormal spark plug conditions (see Table ). 2. Clean the ignition coil contacts at every spark plug change. 3. To help seal out moisture and prevent corrosion use a dielectric silicone grease on the high tension connectors between the coils and the spark plug connectors. Some acceptable dielectric greases are: Du Pont Krytox GPL-206 G.E. G-624 GC Electronics Inspect the wiring harness and connectors for moisture, corrosion, cracks or dirt that can cause a short to ground. Table Spark Plug Specifications INSTALL TIMING LIGHT Figure #1 Cylinder Junction Box 3. Check engine timing at the flywheel using a timing light. See Basic Timing Specification CEC on page in this section. ITEM SPECIFICATION Spark Plug Gasket Spark Plug Gap Spark Plug Torque, P/N 69919, Dry Spark Plug Torque, All Other Plugs, Dry Spark Plug Carrier Torque, Lubricated With Engine Oil mm ( in.) N m (29 39 ft-lb) N m (40 45 ft-lb) N m ( ft-lb) NOTE: The gasket for Waukesha spark plug P/N does not require replacement after plug removal FORM 6284 Third Edition

9 Table Spark Plug Applications ENGINE MODEL FUEL DUTY SIZE AND REACH * For use with shielded integral coil application. ** For use with rocker arm cover flange mounted coils (CSA). UNSHIELDED APPLICATIONS PART NUMBER GAP (IN.) F18/H24G Natural Gas All 18 mm - 13/16 in W F18/H24GL/GLD L36/P48GL/GLD F18/H24GSID L36/P48GSID Natural Gas Natural Gas Natural Gas Standard LCR 160 BMEP High Temp Applications 11:1 CR 176 BMEP 18 mm - 13/16 in W mm - 13/16 in mm - 13/16 in. Natural Gas GLD/2 200BMEP 18 mm - 13/16 in. Natural Gas All 18 mm - 13/16 in (60999T) 69919C European 60999D 69919C European 60999S 60999Z C gap is factory preset C gap is factory preset SHIELDED APPLICATIONS PART NUMBER 60999Y* 69919** 60999Y* 60999U* 69919** 60999S** 60999W** 60999Y* 69919** 60999S** 60999W** 60999Y* 69919** 60999S** 60999W** 60999U* 60999S** GAP (IN.) Table Spark Plug Troubleshooting FIRING TIP APPEARANCE CONDITION REMEDY Light coating of whitish ash, uniformly deposited. Normal with medium to high ash engine oils. No change. Excessive ash buildup. Black oil fouling deposits. Gap bridging. Carbon fouling. NOTE: Stellite is a registered trademark of Stoody Deloro Stellite, Inc. High oil consumption. Wrong oil; oil has high ash content. Poor oil control around the valve guides and rings. Poor oil control. Engine is too lightly loaded. Contaminated or dirty fuel gas. Spark plug firing tip temperature too low. Engine is too lightly loaded. High oil consumption. Change the engine oil type. Change the engine oil. Inspect and replace worn parts as necessary. Replace worn parts as necessary. Adjust the engine load. Add a fuel filter. Use a more open electrode type of plug. Change the plug heat range. Adjust the engine load. Inspect and replace worn parts as necessary. Electrode is burning. Spark plug firing tip temperature is too high. Change the plug heat range. Wear on side of the electrode. Reversed polarity of the ignition coils. Rewire the ignition coils correctly. Aluminum contamination on plug. Engine is operated with severe detonation, causing piston damage. Inspect piston with a borescope; replace worn parts as necessary. Check the spark timing, fuel gas octane. Reduce the engine load. Blue or green deposit on plug and valve. Cobalt fouling from worn Stellite valve. Replace the valve and valve seat. FORM 6284 Third Edition

10 IGNITION MODULE POWER SUPPLY NOTE: Refer to Custom Engine Control Ignition Module Installation, Operation and Maintenance Form 6272 for additional information. An AC to DC power supply is not recommended unless care is taken to eliminate the possibility of a momentary loss of AC power which will result in an engine shutdown. A voltage filter (battery) is recommended to eliminate voltage fluctuations. The CEC Ignition Module will function properly with a power source as defined above. However, if the supply is capable of providing a pulse current (higher current level for a shorter period of time such that the average current is the same), the ignition will utilize that pulse capability. In this case, the voltage fluctuations on the supply wiring, including the ground return to the power source, may cause erratic operation of other electrical devices. For this reason, it is recommended that the ignition power source wiring, specifically the ground return, be sized for at least 30 amps even though the average current will be less than 2 amps (typical). Although the CEC Ignition Module will function with a power supply of VDC, a power supply of VDC (with less than a 2 volt peak-to-peak ripple) is recommended for compatibility with other CEC products. Prior to engine start, complete the following steps: 1. With Ignition Module unpowered, verify power supply is within specifications. 2. Inspect and verify all wiring conforms to local codes and/or regulatory bodies. 3. Inspect and verify all wires are properly grounded. Refer to the engine-specific wiring diagrams received for complete system wiring information. IGNITION MODULE LEDS The CEC Ignition Module is equipped with three diagnostic LEDs on the front of the housing: Power, Pickup, and Application (see Figure ). These LEDs give operators visual confirmation on (1) incoming power, (2) Hall-effect pickup signal, and (3) proper application settings. During normal operation with the engine running the Power LED is on, the Pickup LED is off, and the Application LED is off. When the engine is not running and power is applied to Ignition Module the Power LED is on, the Pickup LED is on, and the Application LED is off. If a different condition exists, refer to the Ignition Module manual (Form 6272) for information. The manual describes what an inerrant LED indicates and provides troubleshooting suggestions to remedy the situation if required. IMPORTANT SELECTOR SWITCH MODEL NUMBER SERIAL NUMBER APPLICATION INPUT VOLTAGE MAXIMUM TEMPERATURE APPLICATION PICKUP POWER DIAGNOSTIC LEDS Figure Ignition Module Diagnostic LEDs CEC IGNITION MODULE TIMING ADJUSTMENT DYNAMIC NOTE: This task applies to Ignition Modules that have already been installed and static timed by a Waukesha Certified Technician. For the initial installation and timing of a CEC Ignition Module, call a Waukesha Certified Technician. Refer to Form 6253 (Previous Model) or Form 6272 (Current Model) Custom Engine Control Ignition Module Installation, Operation, And Maintenance Manual for further information concerning the Ignition Module. The Ignition Module has two 16-position timing switches located under white plastic caps at one end of the box, one marked A and another marked B (see Figure ). Grounding lead D in the 7-pin connector to the engine crankcase gives the timing selected by switch A. Open-circuiting lead D gives the timing selected by switch B. This feature gives the engine operator the ability to switch between two different timing settings to accommodate automatic changeover between two fuels. TIMING SWITCH A TIMING SWITCH B Figure Ignition Module Timing Switches FORM 6284 Third Edition

11 Each timing adjust switch has 16 switch positions (0 15) with a 1 timing variation per position. Switch position 15 gives the most advanced timing, while switch position 0 is full retard. Do not switch from CAUTION position 15 to position 0, or from position 0 to 15 while the engine is running. The timing change is so large that it may damage the engine and/or cause it to shut down. Disregarding this information could result in product damage and/or personal injury. NOTE: The outside temperature of the Ignition Module casing should not exceed 65 C (150 F) during operation. 1. Check the engine's nameplate to determine the exact timing (or most advanced) of the primary and secondary (if equipped) fuels. 2. Run the engine on primary fuel with the D lead (found in the 7-pin connector junction box) grounded to the engine block and the CEC Detonation Sensing Module deactivated. 3. Check engine timing at the flywheel using a timing light (see Figure ). DEGREES BEFORE TOP DEAD CENTER (BTDC) DISPLAYED 6. Check engine timing at the flywheel using a timing light. 7. Adjust the B switch as required to achieve correct timing. Dual fuel ignition adjustments are now complete. To prevent the timing CAUTION from being altered, always replace the white caps over the timing switches once the desired setting has been selected. Disregarding this information could result in product damage. WARNING If a gas engine has been cranked excessively without starting, shut off the gas fuel supply and ignition, and then crank the engine to purge the cylinders and exhaust system of accumulated unburned gas. If this is not done a spark could ignite the gas and cause an exhaust explosion. Failure to comply could cause severe personal injury or death. WARNING If the ignition switch is left in the ON position when a CEC Ignition Module is disconnected, then the spark plugs may fire when the ignition system harness is reconnected, and could cause severe personal injury or death. Before connecting the ignition harness (to the coils) to the CEC Ignition Module, discharge the storage capacitor to ground. Attach one end of a wire lead to the crankcase and then touch the other end to the harness connector pins on the CEC Ignition Module, one at a time. A snap is heard when a capacitor discharges. Figure Flywheel Timing Marks 4. Adjust the A switch as required to achieve correct timing. Single fuel ignition adjustments are now complete. NOTE: Increasing the timing switch position by one will advance the timing one degree. Decreasing the timing switch position by one will retard the timing one degree. 5. Run the engine on secondary fuel with the D lead (found in the 7-pin connector junction box) open and the CEC Detonation Sensing Module deactivated. WARNING As a safety measure, ground all the pins. Some breakerless ignition systems have more than one storage capacitor. Severe personal injury or death could result. NOTE: If the ignition switch is in the OFF position, the capacitor is immediately grounded when the ignition harness is reconnected to the CEC Ignition Module. FORM 6284 Third Edition

12 Table Ignition Module Switch Positions (All Models) SWITCH DEGREES BEFORE TOP DEAD CENTER A A0 A1 A2 B B0 B1 B2 B3 B4 B5 B6 B7 B8 B9 B10 B11 B12 SWITCH DEGREES BEFORE TOP DEAD CENTER A A3 A4 A5 A6 A7 A8 A9 A10 A11 A12 A13 A14 A15 B B13 B14 B15 BASIC TIMING SPECIFICATION CEC Detonation is NOT CAUTION allowed at any time, during engine operation, regardless of the specified timing. If detonation occurs at the specified timing, a timing adjustment must be made to retard the ignition timing until NO audible detonation exists. Engine damage may result if detonation occurs. Do not switch from CAUTION position 15 to position 0, or from position 0 to 15 while the engine is running. The large timing change may cause engine shutdown or damage. NOTE: The CEC Ignition Module contains a grounding stud that must be grounded to the engine. MAGNETO INSTALLATION SETTING IGNITION TIMING STATIC The F18/H24 magneto is located on the engine's left side front gear housing (see Figure ). The L36/P48 magneto is located on the engine's left side rear gear housing (see Figure ). MAGNETO Figure L36/P48 Magneto MOUNTING ADAPTER NOTE: Inspect the magneto drive coupling for wear or damage. Replace the coupling every 4000 hours or when wear in the slots can be seen. 1. The #1 cylinder must be on the compression stroke. Turn engine over (use barring device) in direction of normal engine rotation. Carefully observe flywheel timing marks. Stop turning when correct engine timing is displayed (see Figure ). NOTE: The engine's specification plate indicates the required ignition timing BTDC (Degrees Before Top Dead Center). MOUNTING ADAPTER MAGNETO Figure F18/H24 Magneto FORM 6284 Third Edition

13 NOTE: Do not rotate the crankshaft too far and then back up to the desired timing because the magneto drive gear backlash will be on the wrong side of the gear teeth. The timing will be incorrect by several degrees. Figure Flywheel Timing Marks 2. Rotate magneto drive until timing mark is visible in magneto timing window. The unit is now ready to fire the first cylinder in the firing order (see Figure ). TIMING MARK NAME PLATE DEGREES BEFORE TOP DEAD CENTER (BTDC) DISPLAYED Figure Magneto Static Timing TIMING WINDOW MAGNETO DRIVE SHAFT HARNESS PLUG CONNECTOR 3. Insert magneto into mounting adapter located on engine. Secure magneto with hex head bolts. WARNING Do not leave the ignition switch in the ON position when a breakerless magneto is disconnected for timing or repair. The spark plugs may fire when the ignition system harness is reconnected, causing severe personal injury or death. NOTE: If the ignition switch is in the OFF position, the capacitor is immediately grounded when the ignition harness is reconnected to the magneto. WARNING Shut off the gas fuel supply and ignition if a gas engine has been cranked excessively without starting. Crank the engine to purge the cylinders and exhaust system of accumulated burned gas. If you fail to do this, a spark could ignite the gas, causing an exhaust explosion, resulting in severe personal injury or death. TIMING ADJUSTMENT DYNAMIC NOTE: Check engine timing with magneto ignition every 720 hours. Readjust as necessary. Check engine timing with CEC Ignition Module every 2500 hours. Readjust as necessary. 1. Install timing light (P/N ) onto #1 (RB) cylinder spark plug wire. Be sure all engine connections are completed CAUTION properly before engine startup. Follow all startup procedures. Check that all engine openings are properly closed and that all tools are removed from the engine. Disregarding this information could result in product damage and/or personal injury. 2. Start and run engine at normal operating rpm and temperature. 3. Using timing light strobe, observe ignition timing marks through inspection hole located on left side of flywheel housing. 4. If required, readjust timing by loosening magneto's flange bolts just enough to allow magneto to rotate. Rotate magneto until correct timing mark is aligned with timing pointer. 5. Tighten magneto flange bolts after engine is correctly timed. FORM 6284 Third Edition

14 BASIC TIMING SPECIFICATION Basic ignition timing specification is for a standard cooled engine running on pipeline gas. Pipeline gas is defined as having 900 Btu/ft 3 with a minimum Waukesha Knock Index (WKI ) value of 91. Basic Ignition Timing ( BTDC) (on 900 Btu/ft 3 natural gas) F18/H24G: 20 ± 1 F18/H24GL/GLD: 13 ± 1 F18GL, 8.7: 1 CR: 24 H24GL, 8.7: 1 CR: 25 F18/H24GSID: 23 ± 1 standard temperature cooling F18/H24GSID: 20 ± 1 high temperature cooling L36/P48GL/GLD: 15 ± 1 L36/P48GSID: 23 ± 1 standard temperature cooling L36/P48GSID: 20 ± 1 high temperature cooling Detonation is NOT CAUTION allowed at any time during engine operation, regardless of the specified timing. If detonation occurs at the specified timing, a timing adjustment must be made to retard the ignition timing until NO audible detonation exists. Engine damage may result if detonation occurs. Inspect the drive coupling for wear or damage. Replace the coupling every 4000 hours or when wear in the drive slots can be seen. Do not weld on or CAUTION around engine unless the CEC generator and voltage regulator have been unplugged. Failure to do so may damage the CEC generator, voltage regulator, battery or Ignition Module. The ambient temperature around the CEC CAUTION generator and voltage regulator must not exceed 66 C (150 F). Disregarding this information could result in product damage and/or personal injury. CEC GENERATOR SERVICING The frequency of inspection for the CEC generator is determined largely by the type of operating conditions. High speed operation and high temperatures increase the wear of coupling sleeve and bearings. At regular intervals, inspect the terminals for corrosion and loose connections. Inspect the wiring for frayed insulation. Inspect the mounting bolts for tightness (see Figure ). Figure CEC Generator FORM 6284 Third Edition