Product Overview
Upgrade or rebuild your Honda K-Series engine with the ACL Race Series Conrod Bearing Set 4B1972H0.025, engineered for high-performance, motorsport and tuned engine applications.
Designed for selected Honda and Acura K20 and K24 engines, these ACL Race Series connecting rod bearings feature a +0.025mm / 0.001-inch increased bearing thickness compared with the standard-size version. This makes them suitable where the engine builder requires the corresponding reduced oil clearance after accurately measuring the crankshaft journals and connecting rod housings.
ACL Race Series bearings are widely used in performance engine builds because of their precision manufacturing, consistent wall thickness and suitability for higher-load applications. ACL identifies the 4B1972H family as a tri-metal performance bearing for Honda K-Series applications.
Whether you are rebuilding a naturally aspirated K20, preparing a high-revving Type R engine or assembling a turbocharged K24/K20 hybrid, ACL Race Series bearings are an excellent choice for builders looking for dependable performance under increased engine loads.
Key Features
- Manufacturer: ACL
- Range: ACL Race Series
- Part Number / SKU: 4B1972H0.025 / 4B1972H-.025
- Product Type: Connecting Rod / Conrod Bearing Set
- Bearing Size: +0.025mm / +0.001″
- Quantity: 8 bearing shells
- Application: 4-cylinder Honda / Acura K-Series engines
- Material: Tri-metal performance bearing construction
- Performance application: Suitable for performance, competition and upgraded engines
- Precision-machined for consistent bearing wall thickness
- Designed to support reliable oil clearance when correctly measured and installed
- Suitable for naturally aspirated, supercharged and turbocharged engine builds when the required bearing clearance specification matches
The set contains 8 individual bearing shells, providing the upper and lower shells required for all four connecting rods. Published specifications list identical bearing halves and a standard oil-clearance configuration relative to this +0.025mm bearing size.
What Does +0.025mm Mean?
The 0.025mm designation must not be confused with 0.25mm bearings.
ACL part number 4B1972H-.025 has approximately 0.025mm / 0.001-inch additional bearing thickness compared with the standard-size version.
This means the bearing should only be selected after your crankshaft journal diameter and connecting rod bearing clearance have been properly measured.
Do not order +0.025mm bearings purely because your engine uses a compatible K20 or K24 engine code.
For engine rebuilds, always confirm bearing clearance using appropriate precision measuring equipment or consult your engine builder.
Compatible Engine Families
Published ACL and specialist application data associates the 4B1972H bearing family with engines including:
- Honda K20A
- Honda K20A2
- Honda K20Z / selected K20Z variants
- Honda K24A
- Honda K24A1
- Honda K24A2
- Honda K24A4
- Honda K24A8
The K24A-family applications are also specifically referenced by suppliers for K24A1, K24A2, K24A4 and K24A8 engines.
