Big End Conrod Bearing Shell. Porsche 911 / 914 1965-76

• Porsche 911 1965-1968 2.0L / 912 SWB (F)
• Porsche 911 1970-1973 2.2L / 2.4L / 2.7L RS LWB (F)
• Porsche 914 (1970-1976)

The connecting rod bearing shell fits at the big end of the connecting rod (i.e. the end that attaches to the crankshaft journal). It allows the connecting rod to rotate smoothly about the crankshaft as the engine runs.
It provides a very precise but very small clearance between the bearing surface and the crankshaft journal. Engine oil fills this clearance, forming a thin oil film. This film supports loads from piston movement, combustion forces, and crankshaft rotation, while preventing metal-on-metal contact.

When It Needs Replacing / Symptoms Of Wear:
Rod Knock / Knocking Sound: A deep, rhythmic knock from the engine under load or on acceleration, caused by too much clearance between the bearing shell and crank journal.

• Low Oil Pressure, Especially At Idle: Worn bearing shells increase oil clearance which can reduce oil pressure.
  
• Metal Shavings Or Bearing Material In The Oil: You may see bits of bearing shell material when changing oil or from the oil filter.
  
• Engine Roughness Or Vibration, Especially At Higher RPMs: As bearings wear, the fit becomes loose, causing vibration or uneven performance.
  
• Overheating Or Discoloration Of Bearing Shell On Inspection: If the bearing has been starved of oil or has been operating under stress, it may show signs of overheating.
  
  

• These bearings are critically important for engine reliability. If the big-end bearing fails, it can lead to severe damage: crankshaft journal scoring, connecting rod damage, or total engine failure.
  
• Replacing with correct spec OEM shells restores proper clearance, oil film support, and smooth engine operation.
• Using worn bearings can also lead to poor oil pressure and increased wear elsewhere. It’s a preventative maintenance item, especially in high mileage or rebuilt engines.