3Q78c | Pump Model BH3Q70R8 – Direct-Fit Injection Pump For 380QB Diesel Engines

This KANGDA fuel injection pump assembly, identified by order number 3Q78c and hydraulic head BH3Q70R8, delivers a factory-spec replacement solution for three-cylinder 380QB power units commonly found in agricultural tractors, stationary gensets, and compact industrial equipment. Engineered to match the original 3200 RPM direct-drive governing curve specified by the Wendeng OEM, this mechanical distributor-type pump restores precise fuel metering, stable idle control, and responsive load acceptance without the complexity of electronic retrofits. For workshops servicing Chinese-built diesel fleets, this unit eliminates the guesswork of aftermarket cross-referencing and provides a reliable path to restoring factory-rated performance.

The BH3Q70R8 pump head incorporates a matched plunger-and-barrel set with lapped clearances held to Class A tolerances, ensuring consistent fuel delivery across all three cylinders under varying load conditions. The governor assembly is pre-set at the factory for a rated engine speed of 3200 RPM, with internal mechanical stops that prevent overspeed conditions common in PTO-driven applications. Key dimensional parameters include a drive shaft with a tapered keyway configuration, M12 x 1.5 high-pressure outlet threads compatible with standard 6 mm OD steel injection lines, and an M14 banjo bolt fitting for the fuel inlet connection. The pump housing carries a three-bolt mounting flange with a centering diameter of 68 mm and a bolt circle of 98 mm, matching the Wendeng 380QB gear case interface precisely. Dry weight is approximately 6.4 kg, with overall dimensions of 270 mm in length, 145 mm in width, and 210 mm in height. The delivery valve holder uses two-hole flange fittings that align with original high-pressure pipe assemblies, enabling a direct swap without line modifications.

This KANGDA pump is specifically configured for the Wendeng 380QB engine platform, a three-cylinder direct-injection diesel widely deployed in 25–35 hp agricultural tractors, irrigation pump sets, and mobile concrete mixers. The 3200 RPM governed speed makes this unit suitable for applications requiring rapid throttle response and stable operation under fluctuating loads, such as rotary tiller operation or generator sets powering variable electrical demands. Cross-reference data indicates compatibility with other three-cylinder engines sharing the BQ-series pump drive interface, including certain Yangdong Y380 variants and aftermarket power units that use the same gear-driven pump mounting pattern. Parts managers stocking this SKU can serve customers operating Wendeng-powered equipment as well as those maintaining older Changfa and Jiangdong units that utilized the same injection pump architecture. 

Successful installation begins with verifying the existing pump-to-engine timing shim pack thickness, typically between 1.2 mm and 1.8 mm for the 380QB platform. Use digital calipers to measure the removed shim stack and replicate the dimension with the new unit-deviation alters the start of delivery and directly affects peak cylinder pressure and exhaust gas temperature. Before mounting, inspect the drive coupling rubber insert for cracking or wear; degraded inserts introduce backlash that confuses the mechanical governor and produces erratic speed hunting under load. After torquing the three M8 flange nuts to 28 N·m in a star pattern, pre-fill the pump housing with clean diesel or ISO-VG100 hydraulic oil, as units ship dry from the factory. Prime the low-pressure circuit using the hand primer mounted on the pump body until fuel returns bubble-free through the leak-off line. Crank the engine in 10-second bursts with injector lines loosened at the nozzle end until steady fuel pulses appear at each union, then torque the line nuts to 25–30 N·m.

Q1: How do I confirm this KANGDA pump is the correct match for my 380QB engine beyond the model number?
A: Verify your existing pump's mounting flange bolt pattern (98 mm diameter circle), the shaft taper configuration, and the governor type. This unit is specifically calibrated for direct-drive 3200 RPM operation. Check that your engine's injection timing marks align with the pump's drive flange reference when the engine is at TDC compression-the laser-etched pointer on the pump housing should match the gear case mark at the factory timing setting.

Q2: What's the typical failure mode that indicates replacement rather than repair?
A: When a BH3Q70R8 pump shows loss of prime after sitting, ragged idle that cannot be adjusted out via the idle stop screw, or persistent white smoke on cold start that clears as the engine warms, the plunger-to-barrel clearance has likely exceeded 8 microns. At this point, the lapped mating surfaces are worn beyond economic rebuild limits, and a new pump is the cost-effective solution.

Q3: Can this pump run on biodiesel blends or high-sulfur fuels common in some export markets?
A: Yes, the mechanical BQ-series design is tolerant of ASTM D975 Grade No. 2 diesel and B20 biodiesel blends. However, high-sulfur fuel accelerates wear on the delivery valve and plunger-KANGDA recommends more frequent fuel filter changes and periodic inspection of the governor spring for corrosion when using fuel with sulfur content above 500 ppm.

Q4: Does the pump arrive with the correct shim pack for my specific Wendeng engine?
A: The pump ships without a universal shim pack-the required thickness varies based on individual engine machining tolerances. Reuse your existing shim stack measured with a caliper, or order a shim kit (0.1–0.5 mm increments) separately. The correct static timing is critical; some workshops prefer to verify with a dial gauge for absolute precision.

Q5: What's the realistic shipping timeline for European or North American workshops?
A: Orders typically process within 1–3 business days, with shipping via DHL or FedEx taking 5–7 days to EU destinations and 4–6 days to the US and Canada. Bulk wholesale orders may ship by sea freight with a 25–35 day lead time. Express air freight is available for emergency replacements.