Speed Pro 129M Engine Crankshaft Main Bearing Set

Ford Small Block Main Bearing Set

Speed Pro 129M is a competition-series engine crankshaft main bearing set for Ford small block V8 builds. It is built for standard-size applications with a 3/4 grooved design and Super Duty Alloy construction for performance-focused rebuilds.

Use this main bearing set when rebuilding a Ford 289 or 302 small block for street performance, bracket racing, or other high-output applications. It is a direct-fit choice for a wide range of Mustang, Thunderbird, Cougar, and other Ford and Mercury models listed below.

Key Features

• Part number 129M
• Engine crankshaft main bearing set for Ford small block applications
• Competition Series design
• 3/4 grooved bearing configuration
• Standard size
• Super Duty Alloy construction
• Steel-backed babbitt or bronze alloy bearing material
• Fits Ford 289 and 302 engines

Detailed Description

Speed Pro 129M is engineered for Ford small block engine builds that need a standard-size main bearing set with a 3/4 groove oiling layout. The bearing material uses a steel-backed babbitt or bronze alloy construction, paired with a Super Duty Alloy specification for performance use. This makes it a practical choice for rebuilds where consistent crankshaft support and proper oil control are priorities. The part number 129M is commonly searched for Ford Mustang, Thunderbird, and Mercury Cougar applications, along with other compatible Ford and Mercury vehicles listed in the fitment data.

This part cross-references Monroe Shocks & Struts (e.g., MB529HP, MB529XP) for the same application.

Vehicle Fitment

• Fits 1982-1993 Ford Mustang, N/A; High Performance; with 3/4 Grooves; Standard
• Fits 1979 Ford Mustang, N/A; High Performance; with 3/4 Grooves; Standard
• Fits 1964-1973 Ford Mustang, N/A; High Performance; with 3/4 Grooves; Standard
• Fits 1991-1993 Ford Thunderbird, N/A; High Performance; with 3/4 Grooves; Standard
• Fits 1983-1988 Ford Thunderbird, N/A; High Performance; with 3/4 Grooves; Standard
• Fits 1977-1981 Ford Thunderbird, N/A; High Performance; with 3/4 Grooves; Standard
• Fits 1991-1993 Mercury Cougar, N/A; High Performance; with 3/4 Grooves; Standard
• Fits 1983-1988 Mercury Cougar, N/A; High Performance; with 3/4 Grooves; Standard
• Fits 1977-1981 Mercury Cougar, N/A; High Performance; with 3/4 Grooves; Standard
• Fits 1967-1970 Mercury Cougar, N/A; High Performance; with 3/4 Grooves; Standard
• Fits 1984-1992 Lincoln Mark VII, N/A; High Performance; with 3/4 Grooves; Standard
• Fits 1987-1991 Ford LTD Crown Victoria, N/A; High Performance; with 3/4 Grooves; Standard
• Fits 1987-1991 Mercury Colony Park, N/A; High Performance; with 3/4 Grooves; Standard
• Fits 1979-1991 Mercury Grand Marquis, N/A; High Performance; with 3/4 Grooves; Standard
• Fits 1981-1990 Lincoln Town Car, N/A; High Performance; with 3/4 Grooves; Standard
• Fits 1982-1987 Lincoln Continental, N/A; High Performance; with 3/4 Grooves; Standard
• Fits 1980 Lincoln Continental, N/A; High Performance; with 3/4 Grooves; Standard
• Fits 1977-1986 Ford LTD, N/A; High Performance; with 3/4 Grooves; Standard
• Fits 1965-1974 Ford LTD, N/A; High Performance; with 3/4 Grooves; Standard
• Fits 1982-1986 Mercury Capri, N/A; High Performance; with 3/4 Grooves; Standard
• Fits 1979 Mercury Capri, N/A; High Performance; with 3/4 Grooves; Standard
• Fits 1966-1967 Mercury Capri, N/A; High Performance; with 3/4 Grooves; Standard
• Fits 1980-1983 Lincoln Mark VI, N/A; High Performance; with 3/4 Grooves; Standard
• Fits 1979-1982 Mercury Marquis, N/A; High Performance; with 3/4 Grooves; Standard
• Fits 1977-1980 Lincoln Versailles, N/A; High Performance; with 3/4 Grooves; Standard
• Fits 1975-1980 Mercury Monarch, N/A; High Performance; with 3/4 Grooves; Standard
• Fits 1978-1979 Ford Fairmont, N/A; High Performance; with 3/4 Grooves; Standard
• Fits 1978-1979 Mercury Zephyr, N/A; High Performance; with 3/4 Grooves; Standard
• Fits 1968-1974 Mercury Montego, N/A; High Performance; with 3/4 Grooves; Standard
• Fits 1962-1967 Mercury Villager, N/A; High Performance; with 3/4 Grooves; Standard

Common Uses

• Replacing worn crankshaft main bearings during a Ford 289 or 302 rebuild
• Correcting bearing wear, scoring, or oiling-related damage in a small block Ford engine
• Restoring proper crankshaft support in high-performance street or track engines
• Addressing standard-size main bearing service needs in Mustang, Thunderbird, and Cougar applications
• Supporting a performance rebuild where a 3/4 grooved main bearing layout is required

Installation Notes

Verify crankshaft journal size, bearing clearance, and block condition before assembly. Confirm that your engine is a Ford small block 289 or 302 application and that the standard-size 3/4 grooved configuration matches the build requirements. Clean all oil passages thoroughly and follow the engine builder’s torque and lubrication specifications during installation.

Quality Assurance

Speed Pro positions this component for performance engine use with a focus on value and quality in horsepower-oriented parts. The 129M main bearing set is built for Ford small block applications where consistent fitment and material selection matter in a rebuild.