SPRING 7T0570 - Caterpillar

3406, 3408, 3412 Industrial Engines Used With Allison TC500 Series Torque ConvertersCaterpillar 3400 Series Industrial Engines are commonly used with TC500 Series Torque Converters. In these applications, the engines is coupled (connected) to the torque converter with a 6N9829 Flywheel Adapter Group.
The 6N9667 Flywheel Assembly, used in the adapter group, has twelve 25.4 mm (1.00") diameter holes which are on nearly the same radius as the pin timing holes. When the 6V3100 Timing Indicator Group is used to check engine timing in these applications, the transducer can read the 25.4 mm (1.00") holes instead of the pin timing holes. For this reason, the indications must be adjusted to find the correct timing.
Installation Of The 6V2197 Transducer Group And Its Correction Factors
On most 3406, 3408 and 3412 Engines, the 6V2197 Transducer can be installed either on the left side, as one faces the flywheel, or on the right side of the flywheel housing. But, a different correction factor is needed for each installation.
To correctly install the 6V2197 Transducer, it must be approximately 0.5 mm to 2.0 mm (.02" to .08") from the flywheel surface. It is possible for one of the holes to be in alignment with the pin timing opening in the housing. Make sure the transducer is not in one of these holes. If necessary, remove the transducer, turn the flywheel with an engine rotation tool and install the transducer again.
If the transducer is installed on the left side of flywheel housing, the timing indication will be retarded by approximately 7.6°. This is because the transducer reads the first hole it senses as top center after injection for the No. 1 cylinder. As a result, the transducer reads hole "A", shown in the illustration, instead of hole "B".
Hole pattern in the 6N9667 Flywheel Assembly.When the transducer is installed on the right side of the flywheel housing, the 6V3100 Timing Indicator Group will show the correct timing indication until the fuel system advances to approximately 22.4°. At this point, the injection point moves forward of hole "C", and the indication goes to zero because the transducer will read hole "C" instead of hole "D". The indication will again start to increase, but to correct it approximately 22.4° must be added.
This problem is not present on 3306 Engines Used With TC500 Series Torque Converters.Service Information
When pin timing the engine on its left side, the pin can slide into any of the 25.4 mm (1.00") holes. For correct timing, it must be installed in the threaded timing hole.
Also, when the 6V3121 Multitach Group and the 6V2197 Transducer are used to measure engine speed, the correct pulses per revolution setting (P/REV) is 13 since the transducer will read the twelve 25.4 mm (1.00") holes and the timing hole during one revolution.