Best Crankshaft Main Bearing Cap for Engine Builds

#1 · Best Overall

1. PRW 1735002 Billet Cap

• dimensions: 9.3 x 3.05 x 2.55 in
• Weight: 6.5 lb
• Material: Alloy Steel

Best for: Chevy 350 splayed-cap builds.

Why it ranks #1: Lists Chevy 350 applications from 1967–86 and CNC-machined low-carbon 1020 billet steel, with a 22-degree splayed design.

The 22-degree splayed configuration is the defining feature of this PRW billet-steel cap, listed for Chevy 350 engines from 1967–86. That combination gives builders seeking the specified angled layout an application-focused option, with PRW linking its CNC-machined billet construction to improved stability in the rotating assembly.

PRW identifies low-carbon 1020 billet steel and CNC machining as the cap’s construction, and says its billet caps increase crankshaft rotating-assembly stability while supporting high-horsepower engines. The title’s 22-degree splayed specification helps distinguish this option from straight-cap layouts during parts selection. It is listed for Chevy 350 applications from 1967–86, a clear engine and year range for project planning; the listing does not state a compatible lubricant.

Skip it if you need a straight-hole Chevy 350 cap for a 2-bolt-to-4-bolt block; PRW 1735003 lists that configuration.

This fits builders of listed 1967–86 Chevy 350 applications who specifically need a 22-degree splayed billet-steel cap. Confirm the build calls for that angled layout; it is a different choice from PRW’s straight-hole 1735003 cap.

Listed on Amazon as: PRW 1735002 Billet Steel 22 Degree Splayed Main Bearing Cap for Chevy 350 1967-86

#2 · Best GM OE Option

2. GM Genuine Parts 12686745

• dimensions: 11.25 x 7.88 x 4.35 in
• Weight: 3.4 lb
• Material: Cast Iron, Steel, or Alloy Steel

Best for: GM OE replacement buyers.

Why it ranks #2: GM says this genuine part is designed and validated for its vehicles, and the listing includes a 24-month parts warranty.

GM validation is the defining feature of this crankshaft main bearing cap, giving Chevrolet, Buick, GMC, and Cadillac owners an OE-oriented replacement path. GM says its engineers design and validate these parts for its vehicles, while production updates can incorporate new materials and technologies as designs evolve.

The GM Genuine Parts identity ties the cap to parts installed during production or validated by General Motors, which helps buyers seeking an OE-based service component rather than a general-purpose cap. Its listed material is cast iron, steel, or alloy steel, and the specified compatible lubricant is oil, providing useful service-planning details. The package contains one engine crankshaft main bearing cap; application remains within GM vehicles, so the engine and vehicle configuration still matter.

Skip it if you need a cap expressly listed for a Chevrolet 400 from 1970–80; PRW 1740002 names that application.

GM owners seeking a General Motors OE-based service part are the clearest audience, especially when GM validation matters. Check the cap against the specific engine application, since the supplied information does not narrow coverage to engine or model years.

Listed on Amazon as: GM Genuine Parts 12686745 Crankshaft Bearing Cap

#3 · Best Straight-Hole Option

3. PRW 1735003 Billet Cap

• dimensions: 8.5 x 3.5 x 3 in
• Weight: 5.9 lb
• Material: Alloy Steel

Best for: Chevy 350 straight-hole builds.

Why it ranks #3: Targets Chevy 350 applications from 1967–86, specifies straight holes, and states compatibility with 2-bolt to 4-bolt blocks.

Straight holes and compatibility with 2-bolt-to-4-bolt blocks distinguish PRW 1735003 for Chevy 350 engines from 1967–86. Its billet-steel construction supports PRW’s stated aim of improving crankshaft rotating-assembly stability, while the straight-hole detail helps builders identify the intended cap layout.

PRW describes the cap as CNC-machined from low-carbon 1020 billet steel, a construction it associates with greater stability and strength in high-horsepower rotating assemblies. The title specifies a Chevy 350 from 1967–86, and the description adds straight holes for 2-bolt-to-4-bolt blocks, useful details when planning a block configuration. Grease is listed as the compatible lubricant. These specifics make the cap more targeted than an application-unspecified replacement.

Skip it if you need a 22-degree splayed Chevy 350 cap; PRW 1735002 specifies that layout for 1967–86 engines.

This is a focused option for Chevy 350 builders whose 1967–86 block setup calls for straight holes and 2-bolt-to-4-bolt compatibility. Verify that the build uses this layout, rather than the separately listed 22-degree splayed configuration.

Listed on Amazon as: PRW 1735003 Billet Steel Main Bearing Cap for Chevy 350 1967-86

#4 · Best Chevy 400 Fit

4. PRW 1740002 Splayed Cap

• dimensions: 8.8 x 3.2 x 2.6 in
• Weight: 7.4 lb
• Material: Alloy Steel

Best for: Chevy 400 performance builders.

Why it ranks #4: Specifically lists Chevy 400 applications from 1970–80 and describes CNC-machined low-carbon 1020 billet steel.

A splayed design and billet alloy-steel construction distinguish this PRW cap for Chevrolet 400 applications from 1970–80. PRW says its billet steel caps increase stability across the crankshaft rotating assembly, a benefit aimed at builders strengthening a high-horsepower engine rather than replacing a general-purpose bearing component.

The title specifies a Chevy 400 from 1970–80, giving the intended application a concrete boundary for project planning. Its alloy-steel material and PRW’s description of CNC-machined low-carbon 1020 billet steel connect the construction to the stated goal of increased rotating-assembly stability and engine strength. Oil is listed as the compatible lubricant. The splayed configuration is the defining layout, so it suits a build specifying splayed caps rather than straight-cap hardware.

Skip it if you are building a Chevy 350 from 1967–86; PRW 1735002 specifies that engine and its 22-degree splayed cap.

Choose this for a Chevy 400 build that calls for a splayed billet-steel main cap and values PRW’s stated stability goal. Its listed application is limited to 1970–80 Chevy 400 engines, so it is not a universal replacement.

Listed on Amazon as: PRW 1740002 Billet Steel Splayed Main Bearing Cap for Chevy 400 1970-80

#5

5. PRW 1745402 Billet Cap

• dimensions: 4 x 4 x 8.5 in
• Material: Alloy Steel

Best for: Chevy 396–454 engine builders.

Why it ranks #5: Lists Chevy 396–454 applications from 1966–90 and describes billet steel construction for improved rotating-assembly stability.

Straight-cap configuration for a Chevy 396–454 application is the defining feature of PRW 1745402, listed for engines from 1966–90. Its billet-steel construction gives builders a replacement option tied to PRW’s stated goal of improving stability across the crankshaft rotating assembly in high-horsepower applications.

PRW identifies the cap as CNC-machined from low-carbon 1020 billet steel, and says billet caps increase stability in the rotating assembly while augmenting strength and durability for high-horsepower engines. The title specifies Chevy 396–454 applications from 1966–90, helping narrow the intended engine range. The description calls these straight caps and specifies three each, useful when planning a build. Oil is the listed compatible lubricant, and the package quantity is one.

Skip it if you need a complete four-cap set for a Chevy 454; PRW Steel Main Bearing Caps for Chevy 454 is listed as a set of four.

This is suited to Chevy 396–454 builders needing the specified straight-cap configuration and PRW billet-steel construction. The listing describes three each and one package quantity, so check the build’s required cap count before ordering.

Listed on Amazon as: PRW 1745402 Billet Steel Main Bearing Cap for Chevy 396-454 1966-90

#6

6. PRW Chevy 305/350 Cap

• dimensions: 8.4 x 3 x 2.6 in
• Weight: 5.9 lb
• Material: Alloy Steel

Best for: Chevy 305/350 four-bolt builds.

Why it ranks #6: Identifies Chevy 305/350 fit and a 4-bolt replacement with flat bottom, plus CNC-machined billet steel made from 5140 steel.

A four-bolt replacement with a flat bottom makes this PRW cap a specific option for Chevy 305 and 350 builds. Its CNC-machined 5140 billet-steel construction aligns with PRW’s stated goal of improving strength and crankshaft rotating-assembly stability, giving builders both configuration and material details.

The title identifies Chevy 305/350 applications and a four-bolt, flat-bottom configuration, details that help distinguish the cap during block and parts planning. PRW specifies CNC machining and 5140 steel, which it associates with increased strength and better stability in the rotating assembly. Grease is listed as the compatible lubricant. The supplied information does not give an engine-year range, so the stated engine family and cap layout are the available application cues.

Skip it if you need a Chevy 350 cap explicitly listed for 1967–86 with straight holes; PRW 1735003 names that configuration.

This suits Chevy 305/350 builders who specifically need a four-bolt, flat-bottom replacement and 5140 billet-steel construction. The title does not state model years, so use the block’s required configuration and build information to guide fitment.

Listed on Amazon as: PRW Steel Main Bearing Caps for Chevy 305/350, 4 Bolt Replacement with Flat Bottom

#7

7. PRW Chevy 454 Cap Set

• dimensions: 8.5 x 4 x 4 in
• Weight: 14.9 lb
• Material: Alloy Steel

Best for: Chevy 454 straight-cap sets.

Why it ranks #7: Specifies Chevy 454 straight caps in a set of four, with CNC-machined billet steel manufactured from 5140 steel.

A four-cap set of straight caps for Chevy 454 applications gives this PRW listing a clear configuration advantage for builders planning a replacement set. The caps are CNC-machined billet steel made from 5140 steel, and PRW says the construction improves rotating-assembly stability and strength.

The listed Chevy 454 application and straight-cap layout help identify the intended build configuration before assembly. PRW specifies 5140 steel and CNC machining, connecting the material and manufacturing method to its stated goal of increasing strength and improving crankshaft rotating-assembly stability. The product is sold as a set of four, which lets a builder plan around a defined quantity rather than a single cap. The listing does not give a model-year range.

Skip it if you need a listed 1966–90 Chevy 396–454 application; PRW 1745402 states that year range for its straight caps.

Chevy 454 builders who need four straight caps and value CNC-machined 5140 billet steel should consider this set. Its application title does not specify model years, so use the engine configuration and required cap layout to guide selection.

Listed on Amazon as: Steel Main Bearing Caps for Chevy 454, Straight Caps – Set of 4

#8

8. Speedmaster PCE289.1019

• Weight: 11.91 lb

Best for: Mopar BB 440 race builds.

Why it ranks #8: Provides five 2-bolt billet-steel caps for Mopar and Chrysler BB 440, but states racing-only use and required machine work.

A five-cap set of billet-steel 2-bolt replacements is the key distinction of Speedmaster’s PCE289.1019 for Mopar and Chrysler big-block 440 applications. The listing explicitly limits these caps to racing use, making their intended role clear for builders assembling a competition-focused engine rather than a street vehicle.

The set includes five caps with straight fasteners and a large-journal designation, details that help a builder plan the bottom-end configuration. Billet steel is the stated material, while machine work is required and fasteners are not included; those requirements affect both shop scheduling and the parts list. The product is specified as compatible with Mopar and Chrysler BB 440 applications, and Speedmaster’s legal notice says racing applications only, not street use.

Skip it if you need caps for a street-driven vehicle; Speedmaster specifies this set for racing applications only, not street use.

Race-engine builders working with a compatible Mopar or Chrysler BB 440 can use the five-cap set as a defined starting point. Allow for required machine work and separate fasteners, and keep it off street-use applications.

Listed on Amazon as: Speedmaster PCE289.1019 Compatible with Mopar and Compatible with Chrysler BB 440 OEM 2 Bolt Replacement Billet Steel Main Caps (5 caps)

#9

9. Detroit Diesel 5149220 Cap

Best for: Detroit Diesel service work.

Why it ranks #9: Identifies a genuine Detroit Diesel main bearing cap and casting number, but supplies no engine fit range or dimensional specifications.

Genuine Detroit Diesel identity is the central distinction of this finished crankshaft main bearing cap, identified as part 5149220. For a maintenance or repair workflow calling for a Detroit Diesel component, that manufacturer-specific designation provides a direct starting point for sourcing, with the listing also identifying casting number 5148497.

The listing identifies the item as a new Detroit Diesel main bearing cap and gives both the finished part number, 5149220, and casting number, 5148497. That pair of identifiers can help parts staff or technicians compare the component with service records and existing hardware before work begins. It is presented as a genuine Detroit Diesel part, making manufacturer identity the relevant selection basis; no engine family or fitment range is specified in the supplied description.

Skip it if you need a cap with a stated Chevy 454 application and straight-cap set quantity; PRW Steel Main Bearing Caps for Chevy 454 lists four.

Detroit Diesel service buyers who can identify the needed component by part or casting number are the best match. Use the listed identifiers during selection, since the supplied description does not give an engine family or broader fitment range.

Listed on Amazon as: Detroit Diesel Cap, Crankshaft Main Bearing, Finished Part # 5149220

#10

10. PRW 1738301 2-Bolt Cap

Best for: Two-bolt cap replacements.

Why it ranks #10: The listing identifies a 2-bolt crankshaft main bearing cap, but provides no engine application, material, dimensions, or other fit details.

The 2-bolt designation is the specific configuration stated for PRW 1738301, making it a narrowly identified crankshaft main bearing cap option. For a build whose parts plan calls for a 2-bolt cap, that detail offers a useful selection cue, though the supplied product information gives little additional application guidance.

PRW identifies the item as a 2-bolt crankshaft main bearing cap, so the fastener configuration is the primary practical selection detail available. The manufacturer is listed as PRW, but the supplied specifications do not identify an engine family, material, dimensions, or package quantity. Buyers can use the 2-bolt designation to screen for the required layout, then need application-specific information from their build documentation to establish whether this cap suits the intended engine.

Skip it if you need a 2-bolt-to-4-bolt Chevy 350 block cap with straight holes; PRW 1735003 lists those details.

Consider this only when a PRW 1738301 2-bolt cap matches the requirement already established for the build. The supplied listing does not state an engine application or material, so it offers less selection guidance than application-specific options.

Listed on Amazon as: PRW 1738301 2-Bolt Crankshaft Main Bearing Cap