Usage:
3406B Truck Engines
- SUPPLEMENT: 02/00/89
TRUCK ENGINE NEWS, JUNE 1988, PAGE 4, "Piston Application Guide"for 3406B Truck Engines. Add the sentence that follows after the last sentence in the article.
New 0R2861 and 0R2862 Remanufactured Cylinder Packs are available for use in the 1988 model year trucks engines (see Chart B).
Disregard Chart B in this article. The updated Chart B follows.
--------------- END SUPPLEMENT ---------------
Two new piston groups have been released for use in the 1988 model year production of 3406B Truck Engines. Both new piston groups utilize a double iron band with keystone top and second rings. Plasma coated top rings are now recommended to service all truck engines now using chrome top rings. Both designs display a normal (low) top ring position and loose top land. The new piston groups result in increased compression ratios as compared to the 1987 truck engine families.
The 2W0865 Piston now has dual usage. In the 3406B Truck Engine, the piston operates with a 15.6 to 1 compression ratio (formerly 15.2 to 1) in the 310 hp family only. This differs from the 14.5 to 1 ratio in the 3408 and 3412 Engines. This is a result of the longer stroke employed in the 3406B Truck Engine (6.5 " versus 6.0").
The 7C3406 Piston operates in the 320 hp - uprated truck engines with a compression ratio of 15.2 to 1. (Formerly 14.5 to 1).
The higher compression ratios improve the startability of the engine and contribute to the lower emission levels required for the 1988 model year.
Also, the 9Y3116 Piston Group has been newly-released for parts service only, for use on 310 hp engines and below. This new piston group replaces the 7W3669 and 7C4473 Piston Groups in those engines.The 9Y3116 Piston Group resists top land carbon packing by providing improved pressure balancing of the ring pack.
Chart A lists the piston part numbers for the different truck engine applications for the years 1983 through 1988. Chart B lists some of the usage and design features of the different pistons.
Plasma Coated And Chrome Plated Top Rings
The 3406B Truck Engines have been using a plasma coated top ring in pistons for several years. These rings are 5/32" (3.97 mm) wide. Compared to the former 1/8" (3.18 mm) chrome plated top rings, the plasma coated rings do not break and have handled horsepower increases without ring scuffing.
Some 3406B Truck Engines with lower ratings use a chrome plated, 5/32" wide top ring for maximum cylinder liner reusability. The 1/8" wide 2W1183 Plasma Coated Top Ring is available in parts service for use in special applications such as high sulphur fuel. It can be used as a service alternative in the 1693 Truck Engine, 3406 pre-chamber, and earlier 3406 direct injection engines in place of 8N502 Chrome Ring.
NOTE: Do not install 1/8" wide rings in pistons with 5/32" wide grooves. Ring breakage could occur.
