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SKU: 5M909A-STD
ACL Race Series Standard Size Crankshaft Main Bearing Set - Chevrolet Small Block V8 267 / 305 / 327 / 350 (1967-1998)
The ACL Race Series standard size main bearings for pre-1986 Chevrolet small block V8 engines (267, 305, 327, 350) provide high-strength tri-metal construction designed for performance and race applications. Featuring a hardened steel backing, leaded bronze intermediate layer, and precision electroplated lead-indium overlay, these bearings deliver increased load capacity, better embeddability, and superior oil clearance consistency – ideal for rebuilt or high-performance SBC engines using factory or standard crankshaft main journals.
Key Features
- Tri-Metal Construction: Hardened steel back + copper-lead intermediate + lead-indium overlay for maximum fatigue resistance.
- Race Series Design: Increased eccentricity and crush for better oil clearance and load distribution.
- Standard Size: STD dimensions direct replacement for factory bearings (2.448" / 2.449" main journal).
- Precision Tolerances: Manufactured to ±0.0001" tolerances for consistent oil clearance.
- High Load Capacity: Supports moderate to high horsepower SBC builds (up to 700+ hp with proper prep).
- Oil Groove Design: 3/4 groove in upper shells for improved oil supply.
- Made in Australia: Produced by ACL to ISO 9001 quality standards.
Product Notes
- Part number: 5M909A-STD (set of 5 main bearings, full engine set).
- Fits pre-1986 small block Chevrolet V8 engines with 2-piece rear main seal and standard main journal size.
- Compatible with 267, 305, 327, 350 ci engines (1967-1998) does NOT fit 400 SBC or one-piece seal blocks.
- Available in undersizes (.001", .010", .020") contact for other sizes.
- Recommended for performance and race engines not for stock replacement.
- Individual bearing weight approximately 60-70 grams (full set ~1 kg).
Installation Notes
- Direct replacement requires engine disassembly (crankshaft removal).
- Professional engine builder installation recommended.
- Verify crankshaft journal condition and plastigage clearances during install.
- Use high-zinc engine oil or break-in additive for proper bedding.
This Part Fits
| Year | Make | Model | Engine |
|---|---|---|---|
| 1967-1998 | Chevrolet | Camaro, Corvette, Chevelle, Nova, Truck, etc. | 267 / 305 / 327 / 350 SBC V8 (2-piece rear seal) |
| 1967-1998 | GMC | Sierra, C/K, Suburban, etc. | 305 / 350 SBC V8 (2-piece rear seal) |
| Universal | Any | Small Block Chevrolet V8 | 267-350 ci pre-1986 with standard main journals |
Why Choose ACL Race Series?
- Australian manufacturer with decades of motorsport heritage trusted by engine builders worldwide.
- Race Series bearings proven in high-horsepower street and race SBC engines.
- Superior materials and tolerances vs. OE and many aftermarket brands.
Frequently Asked Questions
- Q: Are these for main or rod bearings?
- A: Crankshaft main bearings 5 pieces for full V8 set.
- Q: Do they fit 400 SBC or one-piece seal blocks?
- A: No, 400 SBC and post-1986 one-piece seal blocks use different main bearings (5M909P series).
- Q: What oil clearance?
- A: Typically 0.0015"-0.0025" with standard crank plastigage recommended.
Shipping & Handling
- Method: Standard ground shipping.
- Package Weight: Approximately 2–3 lbs.
- Box Dimensions (approx): 8" × 6" × 2".
ACL
ACL manufactures performance engine bearings used in race engines across a wide range of motorsports disciplines, from sport compact and drift racing to oval track, drag racing, and land speed record applications. ACL Race Series bearings use a specialized tri-metal construction with a proprietary copper-lead alloy overlay that provides excellent load capacity, conformability, and wear resistance under the high RPM and cylinder pressure conditions of performance engines. Popular ACL Race Series Bearing Applications ACL Race Series bearings are available for main bearings, connecting rod bearings, and thrust washers across a broad range of American, Japanese, and European performance engines including Honda, Toyota, Subaru, Mitsubishi, Nissan, Ford, Chevrolet, and Dodge applications. ACL bearings are manufactured to OEM dimensional tolerances and are available in standard, 0.001-inch, 0.010-inch, and 0.020-inch undersize options to accommodate different crankshaft regrind specificati...
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