ACCUMULATOR 3772988 - Caterpillar

Illustration 1. New valve guide.The new exhaust and inlet valves have a greater face angle to reduce the interference angle with the insert. The valve face angle has been changed from 29.25 0.50° to 29.75 0.25°. This changes the nominal angular difference between the seat and the valve from 1.0° to 0.5°. This smaller angular difference will increase the contact area between the valve and seat to improve the valve and seat service life.
The tolerance on the seat face angle in the cylinder head has been changed from 0.50° to 0.25°. This change is made so that the angle of the valve seat face is not lower than the angle of the valve face.
Illustration 2. Face angle on new exhaust and inlet valve.The new cylinder head assemblies have the new inlet valve seat insert which has a wider valve seat and is made of a softer material. This change will increase the service life of the inlet valve.
Adaptable To: The part numbers of the 7C8130, 4W9560 and 7W0707 Cylinder Head Groups have not changed. The new 9Y1847 Valve Guide is a direct replacement for the former 7N1819 Valve Guide. The new valve guide is adaptable to first production.
The new 7E4609 Exhaust and Inlet Valve is a direct replacement for the former 7C6217 Exhaust and Inlet Valve which has been canceled. The new exhaust and inlet valve is adaptable to first production.
Chart A shows the effectivity of the new valve guides and new valves.
The new 7E5862 Inlet Valve Seat Insert (for parts service) is adaptable to first production by counterboring the inlet seat bore to 60.508 0.025 mm (2.3822 .0010"). This is a 0.51 mm (.020") increase over the former specification. Illustration 3 indicates the inlet valves as seen from the bottom of the head.
Illustration 3. Location of inlet valves. The new 7E5862 Valve Seat Insert MUST NOT be used in the exhaust side of the cylinder head. The 1W1801 Exhaust Valve Seat Insert is still available for parts service for exhaust valve seats.Chart B shows the changes for the cylinder head groups. The new cylinder head assemblies have the new 7E5862 Inlet Valve Seat. The new cylinder head assemblies are adaptable to first production.
Chart C shows the effectivity of the new cylinder head assembly and inlet valve seat inserts.