Product Description
CUMMINS 3920781 OEM ROCKER ARM BOLT (ROCKER LEVER) – 5.9L 6BT (1989–1998)
The genuine Cummins 3920781 rocker arm bolt is the OEM hex-flange fastener that secures the rocker lever shaft to the cylinder head on B-series 5.9L 12-valve engines. If you are refreshing the valvetrain or replacing worn rocker hardware on your 1989–1998 Ram 2500/3500, this bolt restores proper clamp load, keeps valve timing stable, and helps prevent loosening under vibration.
Key Features
- Genuine Cummins OEM hex-flange cap screw for B-series 5.9L 12-valve 6BT engines.
- Correct shank length, thread pitch, and under-head radius for the rocker pedestal.
- High clamp-load consistency to maintain valve lash and rocker geometry under load.
- Flanged head eliminates the need for a separate washer in most OE applications.
- Ideal replacement whenever rocker levers, shafts, or head gaskets are serviced.
Verified Fitment
- Engine: 5.9L 12-valve Cummins 6BT (B-series)
- Automotive: 1989–1998 Dodge Ram 2500 & 3500 with 5.9L 12V Cummins
- Industrial / Off-Highway: Broad 4B / 6B B-series usage and Euro II 5.9L B engines (confirm by ESN before ordering).
For non-automotive and equipment applications, always confirm by engine serial number (ESN) and parts catalog before ordering. This listing is optimized for 1989–1998 Dodge Ram 5.9L 12-valve trucks, but the 3920781 bolt is also found in many industrial B-series configurations.
Cross-Reference & Related Cummins Parts (CPP Diesel)
Pair this rocker arm bolt with matching genuine Cummins valvetrain components available from CPP Diesel:
- CUMMINS 3910811 OEM INTAKE ROCKER LEVER (ROCKER ARM) – 5.9L 12-VALVE (1989–1998)
- CUMMINS 3910810 OEM EXHAUST ROCKER ARM (ROCKER LEVER) – 5.9L 12V (1989–1998)
- CUMMINS 3922488 OEM ROCKER LEVER SHAFT – 5.9L 12V (1989–1998)
- CUMMINS 3937438 OEM ROCKER LEVER ADJUSTING SCREW – 5.9L 12-VALVE (1989–1998)
- CUMMINS 3931623 OEM VALVE TAPPET (LIFTER) – 6BT/4BT 5.9L/3.9L (1989–1998)
What’s Included
- (1) Genuine Cummins Rocker Arm / Rocker Lever Bolt – Part Number 3920781
Specifications for cummins 3920781
| Attribute | Value |
|---|---|
| Brand | Cummins Genuine Parts |
| Part Number | 3920781 |
| Part Type | Rocker arm / rocker lever bolt (hex-flange cap screw) |
| Thread Size | M12 x 1.75 |
| Overall Length | Approx. 180 mm (typical OE length for B-series rocker bolt) |
| Engine Compatibility | 5.9L 12V Cummins 6BT B-series; also used on various 4B/6B and Euro II 5.9L B engines (verify by ESN) |
| Automotive Applications | 1989–1998 Dodge Ram 2500/3500 with 5.9L 12-valve Cummins |
| Cross Reference (ID only) | 3902344, 3903940, J920781, K3920781, selected aftermarket equivalents (FP-3920781, etc.) |
| E-codes / Families | Cummins B-series 4B/6B, including Euro II automotive 5.9L B engines (confirm by ESN & CPL) |
| UPC | 602463141605 |
| GTIN | 00602463141605 |
| Shipping Weight | Approx. 0.4 lb (0.19 kg) packaged |
| Package Dimensions | Width 1.70 in, Height 1.70 in, Depth 9.60 in (typical boxed dimensions) |
| Shipping Method | Standard ground, shipping calculated at checkout via CPP Diesel |
| Country of Origin | Varies by Cummins production batch; typically sourced from Cummins-authorized facilities |
| Prop 65 Warning | This product can expose you to chemicals including substances in engine-related metal components, which are known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov. |
Installation Notes
- Inspect rocker shaft, pedestals, and levers for wear or damage before reassembly.
- Clean bolt threads and threaded holes; chase threads if corrosion or debris is present.
- Use factory torque specifications and tightening sequence from the Cummins service manual.
- Re-check valve lash after rocker hardware has been torqued and the engine has been rotated.
FAQ
WILL THIS FIT MY 1989–1998 5.9L 12-VALVE CUMMINS RAM?
Yes. Cummins 3920781 is the OE rocker arm / rocker lever bolt used on most 1989–1998 Dodge Ram 2500 and 3500 trucks equipped with the 5.9L 12-valve 6BT. Always confirm by VIN or ESN if you suspect prior engine swaps or non-stock parts.
IS THIS A GENUINE CUMMINS PART OR AFTERMARKET?
This listing is for a genuine Cummins bolt, not a generic aftermarket substitute. CPP Diesel sources directly from Cummins-authorized channels so you get OEM metallurgy, fit, and finish.
HOW MANY ROCKER ARM BOLTS DO I NEED TO ORDER?
Bolts are sold individually. Order the quantity required by your specific B-series cylinder head and rocker assembly layout. Many 5.9L 12V applications replace multiple bolts anytime the rockers and shaft are serviced.
WHAT OTHER PARTS SHOULD I REPLACE WHILE I’M IN THERE?
It’s common to pair new bolts with a new rocker lever shaft (3922488), fresh intake rocker lever (3910811), exhaust rocker lever (3910810), and rocker lever adjusting screws (3937438) if any components show wear.
CAN I USE THIS BOLT ON OTHER CUMMINS B-SERIES ENGINES?
Yes, 3920781 appears on many 4B and 6B Cummins applications, including Euro II automotive 5.9L B engines. However, hardware can vary by CPL and ESN, so always confirm usage in your Cummins parts catalog or by serial number.
DO I NEED THREADLOCKER OR WASHERS WITH THIS BOLT?
The factory design uses the integrated hex flange as the bearing surface, so separate washers are generally not required. Use threadlocker only if specifically called for in the Cummins service procedure for your engine family.
