The M50173 Counterbore Setting Master is a precision setup and calibration tool designed for technicians performing cylinder block counterbore machining on Detroit Diesel DD13, DD15, and DD16 engines.
Its job is different from the counterbore cutter itself. The M50173 provides a known reference surface used to establish and verify the dial indicator setting before machining the engine block. This gives the technician a repeatable baseline for setting up the counterbore cutting system and helps eliminate measurement errors that can lead to incorrect liner seating depth.
The M50173 is designed to complement the M50166 DD15/DD16 Counterbore Shim Cutter Tool Kit and M50169 DD13 Counterbore Shim Cutter Tool Kit. The M50166 uses cutter plate 50167 for DD15/DD16 applications, while the M50169 uses cutter plate 50170 for the DD13.
One particularly important detail is that the M50173 is designed to cover all three Detroit engine families with one setting master. A separate DD13 setting block is included with the set, allowing the master to be configured for the different DD13 application.
The kit also includes the extension required to attach the technician's indicator to the setting master. However, the dial indicator itself is NOT included, an important distinction when ordering or setting up the tool.
Accurate counterbore machining is critical because the finished counterbore determines how the cylinder liner is supported in the block. Incorrect cutter setup can produce an uneven or improperly machined liner seating surface, potentially requiring additional machining and complicating final liner installation.
The M50173 provides a dedicated reference fixture so the cutting system can be accurately established before the cutter ever touches the engine block.
Key Features & Benefits
- Precision setting master for Detroit Diesel counterbore machining
- Covers DD13, DD15 and DD16 engines
- One master provides coverage for all three engine families
- DD13-specific setting block included
- Includes indicator extension
- Dial indicator is NOT included
- Provides a repeatable reference for counterbore cutter setup
- Helps reduce cutter-setting and machining errors
- Complements M50166 and M50169 counterbore tooling
- Designed for professional engine rebuilding and machine-shop use
Engine Coverage
- Detroit Diesel DD13
- Detroit Diesel DD15
- Detroit Diesel DD16
This makes the M50173 especially useful for shops servicing multiple Detroit heavy-duty engine platforms because a single master can support both the DD13 and larger DD15/DD16 counterbore systems.
Works With
M50166 – DD15 / DD16 Counterbore Shim Cutter Tool Kit
- Uses 50167 DD15/DD16 Cutter Plate
- Uses 50167-3 replacement cutter bit
M50169 – DD13 Counterbore Shim Cutter Tool Kit
- Uses 50170 DD13 Cutter Plate
- Also uses 50167-3 replacement cutter bit
The M50173 serves as the setting reference supporting these counterbore machining systems.
Typical Applications
- Counterbore cutter setup
- Dial indicator calibration/reference setup
- Cylinder liner counterbore machining
- Counterbore shim cutting
- Cylinder block repair
- In-frame engine overhaul
- Complete engine rebuilding
- Heavy-duty diesel machine-shop service
Why It Matters
A counterbore cutter is only as accurate as its initial setup.
When machining a Detroit DD13, DD15, or DD16 block, an incorrect reference setting can translate directly into an incorrect cut. The M50173 gives the technician a controlled master reference away from the engine, allowing the indicator and cutter setup to be established before machining begins.
That's especially important with expensive DD-series engine blocks. Removing too much material isn't something that can simply be undone.
For a shop already investing in the M50166 or M50169 counterbore systems, the M50173 adds an important layer of repeatability, setup accuracy, and quality control.