Usage:
G3406 (4FD, 1RK),
G3408 (6NB, 6RJ),
G3412 (7DB, 3NK) Engines
- SUPPLEMENT: 12/01/95
Engine News, August 1995, Page 3, "Improved Cylinder Head Group Components And Valve Mechanism Group Components Provide Increased Service Life"
An incorrect New Part Number (6N-7174) is listed for the Rotocoil in all three charts. The correct New Part Number for the Rotocoil is 6N-7154.
In the chart titled "Changes To G3406 (4FD, 1RK) Engines" the part numbers fo the Rocker Arm Group are not correct. The correct New Part Number for the Rocker Arm Group is 4P-5258. The correct Former Part Number for the Rocker Arm Group is 4N-1045.
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Description of Change: The cylinder head groups used on these engines include new basic cylinder head groups. The new basic cylinder head groups include new cylinder head assemblies, new intake valves, and a new rotocoil. The only difference between the new and former rotocoil is the shield has been removed from the new rotocoil. The new intake valve has a new hard face material for increased service life.
The new cylinder head assemblies include a new intake valve seat and new intake and exhaust valve guides. The valve guides have a counterbore at the top to allow oil to collect. This will result in increased lubrication between the valve guide and valve stem. The new intake valve seat is required for compatibility with the new intake valve.
The new valve mechanism groups, for G3408 and G3412 Engines, include new rocker arms. The new rocker arms will supply more oil to the top of the valve guides. This will result in increased service life. The G3406 High Speed Engine has changed from the 6I-0246 Valve Mechanism Group to the 6I-2077 Valve Mechanism Group. Formerly, the 6I-2077 Valve Mechanism Group was used only on the G3406 Low Speed Engine. Now, that valve mechanism group will be used on all G3406 Engines.
Adaptable To: Chart A lists the new and former components for G3406 (4FD, 1RK) Engines. The new components are effective with G3406 (4FD988, 1RK57) Engines. The new components are direct replacements for the former components.
NOTE: The former 6I-4019 Intake Valve Seat should not be used with the new 122-7353 Intake Valve.
Chart B lists the new and former components for G3408 (6NB, 6RJ) Engines. The new components are effective with G3408 (6NB1326, 6RJ44) Engines. The new components are direct replacements for the former components.
Chart C lists the new and former components for G3412 (7DB, 3NK) Engines. The new components are effective with G3412 (7DB1078, 3NK150) Engines. The new components are direct replacements for the former components.
