Here are the standard calibration specs for Caterpillar C7 injectors, clearly and accurately explained. These are the approved specifications used when testing the injector on the test bench.

C7 Injector Specifications on CAT C7 Engine:

1. Opening Pressure
Normal range: 260–300 bar

• Any injector opening below 250 bar → non-compliant and causes black smoke and vibration.
• Above 310 bar → causes slow response and hard starting.

2. Injection Quantity
Measured over 3 main stages:

• Idle:
  Acceptable amount: 8–12 mm³ per 300 pulses
• Full Load:
  Normal value: 45–55 mm³ per 300 pulses
• Return Flow:
  Maximum limit: 20–25 mm³ per minute

Increased return flow indicates:

• Needle wear
• Solenoid problem
• Wear of the orifice plate

3. Spray Pattern
Should be uniform and conical, without:

• Flame breakup
• Thin streaks
• Dripping
• Any distortion — this means the injector will cause smoke or engine shake.

4. Response Time

• Must be fast and stable.
• Slow response indicates an issue with:
• Solenoid
• HEUI oil pressure
• Internal contamination

5. Solenoid Coil Resistance

• Normal value: 2.7–3.2 Ohms
• Less than 2.5 → burnt coil
• More than 3.5 → weak coil, close to failure

6. Internal Leakage
Accepted level: Low leakage
Any increase causes:

• Hard starting
• Hunting (uneven engine speed)
• White smoke
• Loss of p… (text appears incomplete)