BASE AS 3320553 - Caterpillar

The following engine serial numbers appeared incorrectly in the chart for Type 2 Injectors. Put a mark through the incorrect serial numbers and add the correct ones that are shown in the chart.
The following injector color codes appeared incorrectly in the chart for Type 2 Injectors. Put a mark through the incorrect color codes and add the correct ones that are shown in the chart.
The following injector spray angle appeared incorrectly in the chart for Type 1 Injectors. Put a mark through the incorrect spray angle and add the correct spray angle that is shown in the chart.
--------------- END SUPPLEMENT ---------------The 3500 Family of Engines has used a number of different fuel injector assemblies for different operating rpm, power rating and product improvement. This has caused some confusion. This article will summarize: ... all of the injector assemblies that have been used.... the differences between the injectors.... how to identify injector part numbers.... which injectors were used for various applications, operating rpm and power ratings.
All injectors for 3500 Family of Engines are one of two types. For purposes of this article we will refer to them as Type 1 and Type 2. Notice that there are basic design differences between the two types. Refer to Illustrations 1 and 2 for examples of a Type 1 injector, and Illustration 3 for an example of a Type 2 injector. Type 1 injectors have 10.7 mm (.42") dia. plungers and 9 orifice holes in the tip. Type 2 injectors have 11.0 mm (.43") dia. plungers and 10 orifice holes in the tip. When installed in the cylinder head, the Type 1 injector can be identified by a one piece follower and the Type 2 by a two piece follower.
Illustration 1. Type one injector.
Illustration 2. Type one injector tip has identification information which shows orifice diameter in mm, number of orifices and spray angle.Within each type, the injectors share many common parts except for tip assemblies and/or plunger and barrel assemblies (single versus double scroll). Refer to Illustrations 4 and 5 for examples of single and double scroll injectors.
Injectors which have either different tip orifice diameter, spray angle or a different plunger design will have different fuel delivery characteristics and cannot be used as a mixed set in an engine.The charts show differences between the part numbers and serial number ranges for the injectors. The color code referred to in the chart corresponds to the color of a small amount of paint applied to the top of the follower.
Chart A contains Type 1 injector information and Chart B contains Type 2 injector information. The Engine Fuel Specifications Microfiche can also be used to identify the type of injector assembly used.
Illustration 3. Type two injector.
Illustration 4. Example of a single scroll plunger.
Illustration 5. Example of a double scroll plunger.