CYLINDER HEAD AS 3109634 - Caterpillar

1100 and 3100 Series Engines and 3208 Engines In All ApplicationsSUPPLEMENT: 12/14/77ENGINE NEWS, OCTOBER 12, 1977, PAGE 3.In the article "Improved Main, Thrust and Connecting Rod Bearings Have Aluminum Alloy With More Strength" a former part number shown in Chart 6 is wrong. Change 9N7949 to read 9L7949. Also in Chart 6, change the outside diameter for 7N7614 from standard to .010" (0.25 mm).
In Chart 7, change the outside diameter for 9N3057 from .020" (0.25 mm) to .010" (0.25 mm). Also change the inside diameter for 9N3065 from .050" (1.27 mm) to .020" (0.51 mm).
--------------- END SUPPLEMENT ---------------Description of Change: Different main, thrust and connecting rod bearings are now used in the above models. The aluminum alloy in the new bearings is of a higher strength for better resistance to erosion. Also, the bond (method of fasten) between the aluminum alloy and steel is stronger.Adaptable As: The new bearings are a direct replacement for the former bearings as shown in the charts that follow:
In some applications, when the former crankshaft is to be used with the 9N1255 Cylinder Block Service Group, a front main bearing with an upper half that does not have a center groove can be needed. The locating tab on this bearing is also in the center. When the former crankshaft is to be used with a new 9N1255 Cylinder Block Service Group, always check the upper half of the front main bearing in the former cylinder block, or check the crankshaft to find out which type of No. 1 (front) main bearing is needed, before the crankshaft is installed. For crankshafts that have an oil supply passage from the No. 1 (front) main bearing journal to the No. 1 rod bearing, install the main bearing that has an upper half with a groove. For crankshafts that have an oil supply passage from the No. 2 main bearing journal to the No. 1 rod bearing, install the main bearing without a groove in the upper half.
GENERAL INSTALLATION: When a 9N2136, 9N2137 or 9N2138 Short Block Group, or a 9N1255 Cylinder Block Service Group is to be installed or is already installed, use the information that follows:
The 9N1255 Cylinder Block Service Group has a front main bearing with a groove in the upper half and a locating tab in the center