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- KMP Big-End Bearing Set 85042B (0.020" undersize)
KMP Big-End Bearing Set 85042B (0.020" undersize)
Part 85042B is a KMP Brand big-end bearing set: the split shells that sit between each connecting rod and the crankshaft journal. This set is 0.020" undersize.
About this part
Big-end shells carry the full firing load of each piston onto the crankshaft through a thin film of oil. Once that oil film is lost, wear accelerates quickly, so the shells are replaced as a set whenever the crank is ground or the engine is opened up for an overhaul.
When to replace it
- A deep knock under load that rises with engine speed
- Low oil pressure when the engine is hot
- Bronze or copper flakes in the drained oil or filter
- Scored or polished shells found during an inspection
Before you order
Plastigauge the running clearance on assembly, use fresh bolts where the engine maker calls for them, and prime the oil system before the first start.
If the old part has no readable number, send us a clear photo with the engine or alternator nameplate and we will identify it before you buy.
Questions
Do I need standard or undersize shells?
It depends on the crankshaft. A crank that has never been ground takes standard (STD) shells; a reground crank takes the undersize that matches the regrind. Measure the journal or ask the machine shop that did the work.
Should I replace main bearings at the same time?
If the engine is apart for a big-end failure, the mains have usually seen the same oil starvation. Most rebuilders do both.
Specifications
| Part number | 85042B |
|---|---|
| Brand | KMP Brand |
| Range | Big-End Bearing Sets |
| Size | 0.020" undersize |
Not sure it fits?
Send us the number on your old part, or a photo with the engine or alternator nameplate, and we'll confirm the match.
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