DISC-FRICTION 6Y2085 - Caterpillar

3512 ( 4KC ),
3516 ( 3RC ) SI Industrial EnginesSome 3500 Spark-Ignited Low Emission Engines exhibit constant misfire on a single cylinder when the engine is under load. This could happen when the electronically set timing is at the maximum advance position. The magneto distributor rotor may not sufficiently overlap the induction pole for the most advanced cylinder. To verify that a misfire is being caused by this condition, retard the timing by 6 degrees using a SI DDT (Spark-Ignited Digital Diagnostic Tool). If the misfire is corrected by changing the desired timing, the Magneto Calibration should be changed. Changing the magneto calibration will improve the distributor rotor and induction pole overlap, thereby providing more consistent ignition to the most advanced cylinder.
The solution to this problem involves changing the magneto timing. To accomplish this, follow the procedure outlined in "Systems Operation Testing & Adjusting for 3500 Spark-Ignited Engines" SENR4604-01, entitled "Magneto Timing, Set Up-Adjust-Check", Page 69. Step 4 in this procedure should be changed to read as follows: 4. Loosen magneto fastener bolts and adjust timing six degrees ahead of most desired advanced setting. (For desired timing recommendations refer to Recommended BTDC Timing And Fuel Gas Chart found in SENR4604-01).