10-21-2025, 06:33 PM
Case 870 Agri-King Background and Production History
The Case 870 Agri-King was introduced in the early 1970s as part of J.I. Case’s push to modernize its agricultural tractor lineup. Built in Racine, Wisconsin, the 870 was positioned between the smaller 770 and the larger 970, offering a balance of horsepower, weight, and versatility. It featured the naturally aspirated 336BD diesel engine, a robust inline six-cylinder powerplant known for its torque and simplicity. The Agri-King branding emphasized operator comfort and advanced hydraulics, a marketing shift that helped Case compete with John Deere and International Harvester during a fiercely competitive era.
Terminology Note
Owners of vintage Case tractors often struggle to locate accurate service manuals, especially for engine overhauls. The original factory manuals are out of print, and digital archives are incomplete. The 336BD engine, while mechanically straightforward, requires precise torque specs and clearance data for a successful rebuild. Many turn to I&T manuals, which offer general guidance but may lack model-specific details.
Recommendations for sourcing documentation:
The 336BD engine is known for its long stroke and low-end torque, ideal for pulling implements and operating PTO-driven equipment. With proper maintenance, these engines routinely exceed 8,000 hours before requiring major work.
Key specs:
In Saskatchewan, a farmer restored his 870 Agri-King after decades of use on a grain operation. The engine had lost compression on two cylinders, and the overhaul revealed worn rings and pitted sleeves. He sourced parts from a salvage yard in Manitoba and used a combination of I&T specs and local machinist advice to complete the rebuild. After reassembly, the tractor returned to field duty, pulling a 12-foot cultivator with ease.
In Ohio, a collector noted that the 870’s mechanical simplicity made it ideal for restoration projects. He emphasized the importance of cleaning oil galleries and replacing cam bearings—often overlooked during amateur rebuilds.
Conclusion
The Case 870 Agri-King remains a durable and serviceable tractor for those willing to invest in restoration. Its 336BD engine, though lacking turbocharging, delivers reliable power and straightforward maintenance. While service manuals may be scarce, community knowledge and aftermarket resources make it possible to revive these machines for modern use. Whether returning to the field or joining a vintage parade, the 870 continues to represent the mechanical integrity of mid-century American agriculture.
The Case 870 Agri-King was introduced in the early 1970s as part of J.I. Case’s push to modernize its agricultural tractor lineup. Built in Racine, Wisconsin, the 870 was positioned between the smaller 770 and the larger 970, offering a balance of horsepower, weight, and versatility. It featured the naturally aspirated 336BD diesel engine, a robust inline six-cylinder powerplant known for its torque and simplicity. The Agri-King branding emphasized operator comfort and advanced hydraulics, a marketing shift that helped Case compete with John Deere and International Harvester during a fiercely competitive era.
Terminology Note
- 336BD: A 336 cubic inch (5.5L) naturally aspirated diesel engine built by Case, used in multiple Agri-King models.
- No-Turbo: Indicates the engine lacks forced induction, relying solely on atmospheric pressure for air intake.
- I&T Manual: A third-party service manual series offering mechanical specifications and procedures for agricultural equipment.
- Overhaul: A complete disassembly and rebuild of the engine, including replacement of pistons, bearings, seals, and gaskets.
Owners of vintage Case tractors often struggle to locate accurate service manuals, especially for engine overhauls. The original factory manuals are out of print, and digital archives are incomplete. The 336BD engine, while mechanically straightforward, requires precise torque specs and clearance data for a successful rebuild. Many turn to I&T manuals, which offer general guidance but may lack model-specific details.
Recommendations for sourcing documentation:
- Search for I&T Manual #C-30, which covers Case tractors including the 870
- Contact vintage tractor clubs or online forums specializing in pre-1980 Case equipment
- Explore agricultural university archives or rural library collections
- Verify engine serial numbers before ordering parts or manuals
The 336BD engine is known for its long stroke and low-end torque, ideal for pulling implements and operating PTO-driven equipment. With proper maintenance, these engines routinely exceed 8,000 hours before requiring major work.
Key specs:
- Bore: 4.125 inches
- Stroke: 5.00 inches
- Compression Ratio: ~16.5:1
- Rated Power: ~85 HP at 2,100 RPM
- Fuel System: Inline mechanical injection pump
- Change oil every 100 hours using high-zinc diesel-rated oil
- Replace fuel filters every 200 hours to prevent injector fouling
- Adjust valve lash annually to maintain combustion efficiency
- Inspect head gasket and coolant passages during rebuilds
- Use OEM or high-quality aftermarket sleeves and pistons for longevity
In Saskatchewan, a farmer restored his 870 Agri-King after decades of use on a grain operation. The engine had lost compression on two cylinders, and the overhaul revealed worn rings and pitted sleeves. He sourced parts from a salvage yard in Manitoba and used a combination of I&T specs and local machinist advice to complete the rebuild. After reassembly, the tractor returned to field duty, pulling a 12-foot cultivator with ease.
In Ohio, a collector noted that the 870’s mechanical simplicity made it ideal for restoration projects. He emphasized the importance of cleaning oil galleries and replacing cam bearings—often overlooked during amateur rebuilds.
Conclusion
The Case 870 Agri-King remains a durable and serviceable tractor for those willing to invest in restoration. Its 336BD engine, though lacking turbocharging, delivers reliable power and straightforward maintenance. While service manuals may be scarce, community knowledge and aftermarket resources make it possible to revive these machines for modern use. Whether returning to the field or joining a vintage parade, the 870 continues to represent the mechanical integrity of mid-century American agriculture.
