Usage:
3406B Truck Engines - 310 HP Family
The 310 HP Family of 3406B Truck Engines has been improved for 1985. This 3406 Truck Engine family has three ratings; 231 kW (310 HP) at 1800 RPM, 231 kW (310 HP) at 2100 RPM, and 213 kW (285 HP) at 1600 RPM. There are also several secondary ratings of this engine family. These ratings have component improvements that were designed to optimize performance and provide improved fuel economy. The improvements for the 310 HP Family of 3406B Truck Engines are in effect with 7FB27302.
Piston
The new piston has increased the compression ratio from 14.5:1 to 15.2:1. The top piston ring has been changed to a 5/32" chrome face ring and its position has been raised in relation to the piston crown to help decrease white smoke and emission levels.
Valve Camshaft
The new valve camshaft has a rounded profile instead of the plateau on the nose of the exhaust lobe of the former camshaft. The new valve camshaft has the same high lift as the former camshaft, but gives added overspeed protection.
Fuel Injection Nozzle
The fuel injection nozzle used in the improved engine has 0.241 mm (.0095 ") orifices. The fuel injection nozzle that was used in the former engine had 0.268 mm (.0105 ") orifices. The smaller orifices give a more atomized fuel pattern. The fuel lines have not been changed.
Turbocharger
The new turbocharger has less inertia to improve engine acceleration response and load startability. Shims are now used to set the clearances between the compressor wheel and the housing.
Timing
Both the static and dynamic timing have been changed. The static timing is now 18 ° BTC instead of 24° BTC. Dynamic timing is 9°. Advance starts at 1125 rpm and is fully advanced at 1750 rpm. The former dynamic timing was 7 ° and started at 1400 rpm and was fully advanced at 1850 rpm.
Also, a new fuel injection pump camshaft along with a spring in the timing advance is used in these new engines.
Because of the fuel injection nozzle differences, the fuel settings for the new 310 HP Family of 3406B Truck Engines are different from previous comparable horsepower ratings and have different performance specification (0T) numbers.
The OT numbers for the new 310 HP Family engines are shown in Chart A.
Because these changes give the best performance to the 310 HP Family, the rated horsepower can not be increased without component damage and shortened engine life. Derating the 298 kW (400 HP) and 261 kW (350 HP), etc. to 310 HP Family ratings requires the installation of the same components used in the 310 HP Family engines.
The part numbers of the important changes to the 1985, 310 HP Family of 3406B Truck Engines are shown in Chart B.
