EMISSION REGULATIONS FOR ON-HIGHWAY VEHICLE ENGINES

TM 5-3895-346-14

ENGINE TUNEUP

ENGINE OVERHAUL

EMISSION REGULATIONS FOR ON-HIGHWAY VEHICLE ENGINES

On-highway vehicle and coach engines built by Detroit Diesel Allison are certified to be in compliance with

Federal and California Emission Regulations established for each model year beginning with 1970.

Engine certification is dependent on five physical characteristics:

1.

Fuel injector type.

2.

Maximum full-load engine speed.

3.

Camshaft timing.

4.

Fuel injector timing.

5.

Throttle delay (orifice size). Tables 1 through 6 summarize all of the pertinent data concerning the

specific engine configurations required for each model year.

When serviced, all on-highway vehicle and coach engines should comply with the specifications for the specific

model year in which the engine was built.

Trucks in a fleet containing engines of various model years can be tuned to the latest model year, provided the

engines have been updated to meet the specifications for that particular year.

TABLE 1 (1970-1973 Engines)

Year

1970

1971

1972

1973

Engines

4-53N

Injectors

N40

C40

N45

C45

N50

C50

Maximum Full-load

Engine Speed †

2800

Camshaft Timing

Adv.

Injector Timing ‡

1.460 inches

Timing Gage

J 1583

Throttle Delay

No

Yes*

Yield Link

-

* Throttle delay must have 0.016 inch diameter orifice.

† No-load engine speed will vary with injector size and governor type.

‡ The adjusted height of the fuel injector follower in relation to the injector body.

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