This is the .030" oversized lower press fit counterbore bushing that is made for use on the Cummins: 250, 335, 350, 855, 5 1/2 NH, NTC Inline 6 cylinder, V-12 5 1/2 Bore Motors. Outer diameter of the bushing is 6.784"
6.299 X 6.784 X .781
Made In USAThe LS-8043 .030" Oversize Lower Press-Fit Counterbore Bushing is a precision-machined repair bushing engineered to restore worn or damaged lower press-fit (LPF) bores in Cummins heavy-duty diesel engine blocks. Designed for professional engine rebuilding, this oversized repair bushing provides a cost-effective solution for salvaging engine blocks that would otherwise be considered unserviceable due to excessive wear in the cylinder liner pilot bore.
The LS-8043 features a +.030" oversize outside diameter and is installed after the damaged lower press-fit bore has been machined to the proper repair dimension. Once pressed into the block, the bushing restores the critical interference fit required to securely support the cylinder liner and maintain proper liner stability throughout engine operation. The bushing dimensions are:
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Inside Diameter: 6.299"
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Outside Diameter: 6.784"
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Height: 0.781"
Cummins Lower Press-Fit engines rely on the lower pilot bore—not just the upper counterbore—to properly locate and stabilize the cylinder liner. When this bore becomes oversized due to fretting, cavitation, corrosion, or repeated rebuilds, the liner can lose its press fit, resulting in:
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Cylinder liner movement
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Loss of liner protrusion
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Coolant leakage
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Counterbore fretting
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Premature head gasket failure
The LS-8043 restores the structural integrity of the lower bore, allowing the engine block to be remachined to OEM specifications rather than replaced. This makes it an essential component for heavy-duty machine shops performing premium Cummins engine rebuilds.
Key Features & Benefits
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Precision +.030" oversize lower press-fit repair bushing
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Restores worn or damaged LPF cylinder liner bores
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Salvages expensive Cummins engine blocks
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Re-establishes proper cylinder liner interference fit
-
Maintains liner stability and correct protrusion
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Precision-machined for accurate installation
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Manufactured from high-quality cast iron for long service life
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Ideal for professional engine rebuilding and machine shop repairs
Engine Coverage
Designed for Cummins 5.5-inch bore Lower Press-Fit (LPF) engines, including:
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Cummins 250
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Cummins 335
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Cummins 350
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Cummins 855
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Cummins NH
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Cummins NT
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Cummins NTC
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Cummins N14
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Cummins V12 (5½" Bore)
Typical Applications
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Lower press-fit bore restoration
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Counterbore repair
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Engine block salvage
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Cylinder liner support repair
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Complete engine overhaul
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Heavy-duty diesel machine shop rebuilding
Why It Matters
Many rebuilders focus on repairing the counterbore ledge while overlooking the lower press-fit bore. However, if the LPF bore has lost its interference fit, the liner can move under combustion loads regardless of counterbore condition.
The LS-8043 restores the lower pilot bore to the proper press-fit condition, allowing the liner to seat correctly and maintain proper protrusion. This helps prevent coolant leakage, liner movement, and premature head gasket failure while extending the service life of the rebuilt engine. Cummins service procedures specify machining and repair of oversized LPF bores when inspection measurements exceed allowable tolerances.
The LS-8043 .030" Oversize Lower Press-Fit Counterbore Bushing is a precision-machined repair bushing engineered to restore worn or damaged lower press-fit (LPF) bores in Cummins heavy-duty diesel engine blocks. Designed for professional engine rebuilding, this oversized repair bushing provides a cost-effective solution for salvaging engine blocks that would otherwise be considered unserviceable due to excessive wear in the cylinder liner pilot bore.
The LS-8043 features a +.030" oversize outside diameter and is installed after the damaged lower press-fit bore has been machined to the proper repair dimension. Once pressed into the block, the bushing restores the critical interference fit required to securely support the cylinder liner and maintain proper liner stability throughout engine operation. The bushing dimensions are:
- Inside Diameter: 6.299"
- Outside Diameter: 6.784"
- Height: 0.781"
Cummins Lower Press-Fit engines rely on the lower pilot bore—not just the upper counterbore—to properly locate and stabilize the cylinder liner. When this bore becomes oversized due to fretting, cavitation, corrosion, or repeated rebuilds, the liner can lose its press fit, resulting in:
- Cylinder liner movement
- Loss of liner protrusion
- Coolant leakage
- Counterbore fretting
- Premature head gasket failure
The LS-8043 restores the structural integrity of the lower bore, allowing the engine block to be remachined to OEM specifications rather than replaced. This makes it an essential component for heavy-duty machine shops performing premium Cummins engine rebuilds.
Key Features & Benefits
- Precision +.030" oversize lower press-fit repair bushing
- Restores worn or damaged LPF cylinder liner bores
- Salvages expensive Cummins engine blocks
- Re-establishes proper cylinder liner interference fit
- Maintains liner stability and correct protrusion
- Precision-machined for accurate installation
- Manufactured from high-quality cast iron for long service life
- Ideal for professional engine rebuilding and machine shop repairs
Engine Coverage
Designed for Cummins 5.5-inch bore Lower Press-Fit (LPF) engines, including:
- Cummins 250
- Cummins 335
- Cummins 350
- Cummins 855
- Cummins NH
- Cummins NT
- Cummins NTC
- Cummins N14
- Cummins V12 (5½" Bore)
Typical Applications
- Lower press-fit bore restoration
- Counterbore repair
- Engine block salvage
- Cylinder liner support repair
- Complete engine overhaul
- Heavy-duty diesel machine shop rebuilding
Why It Matters
Many rebuilders focus on repairing the counterbore ledge while overlooking the lower press-fit bore. However, if the LPF bore has lost its interference fit, the liner can move under combustion loads regardless of counterbore condition.
The LS-8043 restores the lower pilot bore to the proper press-fit condition, allowing the liner to seat correctly and maintain proper protrusion. This helps prevent coolant leakage, liner movement, and premature head gasket failure while extending the service life of the rebuilt engine. Cummins service procedures specify machining and repair of oversized LPF bores when inspection measurements exceed allowable tolerances.