Best engine main bolts for 2026 are high‑strength, accurate-fit options like ARP 8740 chrome‑moly and dedicated GM LS main cap kits.
Choose bolts that match OEM tolerances, handle higher preload, and resist fatigue for heavy-duty or high-performance use.
Consider full main bolt and stud sets from reputable makers such as Michigan Motorsports for complete fitment and reliability.
Also keep corrosion protection and correct torque procedures in mind during installation.
| GM LS Series Main Cap Bolt Kit (2000–2015) |
| Direct OEM Fit | Compatibility: GM LS-series engines (1997–2015) — LS1/LS2/LS6/LS7/LS9; 4.8L–5.7L etc. | Function: Main cap/main cap side and windage tray fastening (main bolts) | Quantity / Kit Composition: 30 bolts (10 inner main, 10 outer/windage, 10 side bolts) | VIEW LATEST PRICE | Read Our Analysis |
| LS Rear Main Cover Flange Bolts for LS/LT Engines |
| Corrosion-Resistant Pack | Compatibility: LS/LT family (LS1, LS2, LS3, LSX, LT1, LT2) | Function: Rear main cover flange fastening (rear main cover bolts) | Quantity / Kit Composition: 12 bolts (rear main cover flange bolts) | VIEW LATEST PRICE | Read Our Analysis |
| Michigan Motorsports LS Main Bolt & Stud Kit |
| Performance Upgrade | Compatibility: LS-series engines (1997–2013) — LS1/LS2/LS3, LQ4/LM7/etc.; 4.8L–6.2L | Function: Bottom-end fastening — main bolts and studs to secure main caps/crank | Quantity / Kit Composition: Complete kit (mix of main bolts and studs — full bottom-end set) | VIEW LATEST PRICE | Read Our Analysis |
| Rear Main Cover Flange Bolts for LS/LT Engines (12) |
| Wide Compatibility | Compatibility: LS/LT family (extensive LS cast codes listed, plus LT1/LT2) | Function: Rear main cover flange fastening (rear main cover bolts) | Quantity / Kit Composition: 12 bolts (rear main cover flange bolts) | VIEW LATEST PRICE | Read Our Analysis |
| ARP High Performance Main Bolt Kit for Chevy Small Block |
| Professional Grade | Compatibility: Select Chevrolet small block (2‑bolt main, small journal) | Function: Main fasteners for Chevy small block main caps (high-performance main bolts) | Quantity / Kit Composition: Main bolt kit (quantity for small block 2‑bolt main set — complete main bolt set) | VIEW LATEST PRICE | Read Our Analysis |
| ARP High Performance Main Bolt Kit for Ford 351W |
| Race-Ready Strength | Compatibility: Select Ford small block 351W (2‑bolt main) | Function: Main fasteners for Ford 351W main caps (high-performance main bolts) | Quantity / Kit Composition: Main bolt kit (quantity for 351W 2‑bolt main set — complete main bolt set) | VIEW LATEST PRICE | Read Our Analysis |
| 12pc Engine Stand Bolt Kit for LS Engines |
| Workshop Essential | Compatibility: LS-series engines (LSX, LS, LS1 family; 4.8L–6.2L) | Function: Engine stand / block mounting/stand bolt set (engine stand bolts for LS engines) | Quantity / Kit Composition: 12 bolts (engine stand bolt kit) | VIEW LATEST PRICE | Read Our Analysis |
More Details on Our Top Picks
GM LS Series Main Cap Bolt Kit (2000–2015)
Should you’re rebuilding or upgrading an LS engine and you want reliability without guesswork, this GM LS Series Main Cap Bolt Kit is the best choice because it matches the exact OEM fit and function for 2000 to 2015 LS families. You’ll get 10 inner main bolts to secure main caps inside the block, 10 outer bolts that hold the windage tray and outer caps, and 10 side bolts that anchor caps from the sides. They replace OEM numbers 12560272, 12560273, and 12556127. You can trust fitment across 1997 to 2015 LS engines including 4.8L, 5.3L, 5.7L, LS1, LS2, LS6, LS7, and LS9.
- Compatibility:GM LS-series engines (1997–2015) — LS1/LS2/LS6/LS7/LS9; 4.8L–5.7L etc.
- Function:Main cap/main cap side and windage tray fastening (main bolts)
- Quantity / Kit Composition:30 bolts (10 inner main, 10 outer/windage, 10 side bolts)
- Material / Strength:High-strength replacement bolts (designed to match OEM specifications)
- Intended Use Case:Rebuilds/repairs/upgrades of GM LS mains
- Corrosion / Finish:OEM-equivalent finish (engineered as direct replacements; corrosion resistance implied)
- Additional Feature:Direct OEM cross-reference
- Additional Feature:Includes windage-tray bolts
- Additional Feature:Covers 1997–2015 range
LS Rear Main Cover Flange Bolts for LS/LT Engines
Provided you want a reliable, heavy-duty bolt set for LS and LT engines, these LS rear main cover flange bolts are a great fit because they combine strength, corrosion resistance, and straightforward installation. You get 12 high-strength grade 10.9 bolts that match LS1, LS2, LS3, LSX, LT1, and LT2 applications. They resist rust and hold up over time, so you can trust them on a rebuild or repair. To install, remove the old bolts, align the new ones with the flange holes, and secure them. The maker backs them with a 100% confidence guarantee and support should assistance be required.
- Compatibility:LS/LT family (LS1, LS2, LS3, LSX, LT1, LT2)
- Function:Rear main cover flange fastening (rear main cover bolts)
- Quantity / Kit Composition:12 bolts (rear main cover flange bolts)
- Material / Strength:Grade 10.9 high-strength steel, corrosion-resistant
- Intended Use Case:Rear main cover replacement/repair on LS/LT engines
- Corrosion / Finish:Corrosion-resistant finish (manufacturer states long service life)
- Additional Feature:Grade 10.9 bolts
- Additional Feature:12-piece package
- Additional Feature:Manufacturer guarantee
Michigan Motorsports LS Main Bolt & Stud Kit
In case you want a worry-free bottom end for your LS build, the Michigan Motorsports LS Main Bolt and Stud Kit is the smart choice for both daily drivers and high-output engines. You’ll get a full set of main bolts and studs that fit 1997–2013 LS engines like LS1, LS2, LS3, LQ4, and others. The studs replace select bolts to center the crank and stop cap walk while bolts add clamping where needed. Made from high-strength steel, they resist stretch, heat, and torque. You’ll feel more confidence at high RPM and under forced induction, whether rebuilding, swapping, or upgrading.
- Compatibility:LS-series engines (1997–2013) — LS1/LS2/LS3, LQ4/LM7/etc.; 4.8L–6.2L
- Function:Bottom-end fastening — main bolts and studs to secure main caps/crank
- Quantity / Kit Composition:Complete kit (mix of main bolts and studs — full bottom-end set)
- Material / Strength:Premium-grade high-strength steel (heat/torque resistant)
- Intended Use Case:Rebuilds, swaps, performance builds — bottom-end reinforcement
- Corrosion / Finish:Durable high-strength finish (designed to resist heat/corrosion in service)
- Additional Feature:Includes main studs
- Additional Feature:Reduces main-cap walk
- Additional Feature:Suited for forced-induction
Rear Main Cover Flange Bolts for LS/LT Engines (12)
In case you want a reliable, hassle free solution for sealing the rear main on an LS or LT engine, these Rear Main Cover Plate Flange Bolts are made for you. You’ll get a 12-pack of zinc plated, grade 10.9 hardened steel bolts built for LS1 through LS9 and a long list of LM, LQ, LH, L series cast codes plus LT1, LT2 and LT4 families. The flanged head removes the need for washers, so you’ll fit them quickly during reassembly. They match factory needs, resist corrosion, and feel solid in your hands, giving confidence as you finish the job.
- Compatibility:LS/LT family (extensive LS cast codes listed, plus LT1/LT2)
- Function:Rear main cover flange fastening (rear main cover bolts)
- Quantity / Kit Composition:12 bolts (rear main cover flange bolts)
- Material / Strength:Grade 10.9 hardened steel, zinc-plated
- Intended Use Case:Rear main cover replacement/repair on LS/LT engines
- Corrosion / Finish:Zinc-plated finish for corrosion protection
- Additional Feature:Integrated flanged heads
- Additional Feature:Zinc-plated finish
- Additional Feature:Very broad cast-code list
ARP High Performance Main Bolt Kit for Chevy Small Block
Should you plan to rebuild a Chevy small block for high power or racing use, choose the ARP 1345002 High Performance main bolt kit because it gives professional builders the strength and peace of mind they need. You’ll find these 2-bolt small journal bolts replace weaker OEM fasteners and fit select Chevy small block engines. They’re forged from 8740 chrome-moly steel with a generous under-head radius, and they have rolled threads to fight fatigue. Rated at 180,000 PSI tensile strength, they outclass Grade 8 and last far longer under stress. You’ll feel confident installing a kit meant for tough, high-performance rebuilds.
- Compatibility:Select Chevrolet small block (2‑bolt main, small journal)
- Function:Main fasteners for Chevy small block main caps (high-performance main bolts)
- Quantity / Kit Composition:Main bolt kit (quantity for small block 2‑bolt main set — complete main bolt set)
- Material / Strength:8740 chrome-moly forged steel (ARP high-strength)
- Intended Use Case:High-performance rebuilds/race/engine builder use (Chevy small block)
- Corrosion / Finish:High-quality forged steel finish (designed for durability; protective treatment implied)
- Additional Feature:8740 chrome-moly steel
- Additional Feature:180,000 PSI tensile
- Additional Feature:Rolled threads / under-head radius
ARP High Performance Main Bolt Kit for Ford 351W
Should you want rock-solid reliability for a high-revving or heavy-duty 351W build, the ARP High Performance main bolt kit is the choice for you. You’ll get a premium replacement for OEM fasteners, made for pros and serious builders. The bolts are forged from 8740 chrome-moly steel with a generous under-head radius and rolled threads, so they seat cleanly and resist wear. They’re rated at 180,000 PSI, far stronger than Grade 8, and offer about 1000% longer fatigue life than most main bolts. You’ll feel confident installing them, aware they meet exacting engine building standards.
- Compatibility:Select Ford small block 351W (2‑bolt main)
- Function:Main fasteners for Ford 351W main caps (high-performance main bolts)
- Quantity / Kit Composition:Main bolt kit (quantity for 351W 2‑bolt main set — complete main bolt set)
- Material / Strength:8740 chrome-moly forged steel (ARP high-strength)
- Intended Use Case:High-performance rebuilds/race/engine builder use (Ford 351W)
- Corrosion / Finish:High-quality forged steel finish (designed for durability; protective treatment implied)
- Additional Feature:Forged 8740 steel
- Additional Feature:180,000 PSI tensile
- Additional Feature:Race/pro builder focused
12pc Engine Stand Bolt Kit for LS Engines
Should you want a no-fuss bolt kit that fits a wide range of LS engines and keeps your rebuild on track, this 12-piece engine stand bolt kit is a smart pick for you. You get high-strength grade 10.9 metric flange bolts that meet JIS specs, so you won’t need washers and installation stays simple. The transparent zinc coating helps resist rust, and thread quality is engineered to avoid seizing, which keeps your work calm and predictable. It fits many LS variants like LSX, LS1, L92, and more. GSTP supports after-sale questions and aims to reply within 24 hours, so you’re covered.
- Compatibility:LS-series engines (LSX, LS, LS1 family; 4.8L–6.2L)
- Function:Engine stand / block mounting/stand bolt set (engine stand bolts for LS engines)
- Quantity / Kit Composition:12 bolts (engine stand bolt kit)
- Material / Strength:Grade 10.9 high-strength metric flange bolts, zinc coated
- Intended Use Case:Engine stand mounting / service use for LS engines
- Corrosion / Finish:Transparent zinc coating for rust/corrosion protection
- Additional Feature:JIS flanged-head design
- Additional Feature:Transparent zinc coating
- Additional Feature:Anti-seize thread quality
Factors to Consider When Choosing Engine Main Bolts
Whenever you pick engine main bolts, you’ll want to focus on material strength and corrosion resistance so the bolts hold up under stress and time. Also check thread type, torque specifications, and fitment compatibility because those details determine correct installation and long-term safety. As you compare options, keep those factors together so you can trust the fit and performance without second guessing.
Material Strength
Because engine main bolts take the engine’s load, you want fasteners that won’t stretch, crack, or lose clamping force under heat and vibration. You should pick high-strength steels like chrome-moly with tensile ratings around 150,000 to 180,000 PSI for tough applications. Check bolt grade or class, such as metric 10.9 or SAE Grade 8 and 8740 spec, since those numbers mean better yield and tensile strength and less chance of stretching. Prefer forged or rolled threads with generous under-head radii because they enhance fatigue life and spread clamping load more evenly than cut-thread parts. Also confirm thermal stability and heat treatment specs so bolts hold clamping force at high temperatures. Finally, weigh corrosion coatings only provided they don’t change torque behavior.
Thread Type
You’ve already picked high-strength steel and paid attention to heat treatment, so now you want bolts whose threads will hold preload and resist wear under stress. Choose fine threads whenever you need stronger tensile capacity and tighter preload control. They give more precise clamp load and suit high-stress mains. Match thread engagement to the mating material, aiming for at least 1 to 1.5 times the bolt diameter to avoid stripping and keep clamp force. Pick a tight thread fit class like Class 3A/3B or metric 6g/6H to reduce play and improve repeatability. Look for rolled threads and protective coatings to cut fatigue, galling and corrosion during assembly and service. Finally, always verify thread direction and handedness so you don’t fit the wrong bolt.
Torque Specifications
Getting torque right matters more than you might realize, so let’s get it straight from the start: main bolt torque controls the clamp force that keeps your crankshaft and bearings aligned, and wrong numbers can lead to bearing failure or cap walk. You’ll always follow the manufacturer specified torque value and sequence in ft·lb or Nm. Many bolts need a two-step method, like an initial torque then an angle torque, to reach proper preload and offset thread friction. Clean, dry threads or the correct lubricant matter because they alter the torque-to-preload link, so match the spec. Use a calibrated torque wrench or angle gauge every time. Replace stretch type bolts after one use. Finally, recheck torque after a few heat cycles whenever the maker recommends it.
Corrosion Resistance
At any time you choose main bolts, consider about corrosion resistance as a safety step that protects threads, clamp load, and long-term engine health. You want bolts made from corrosion resistant alloys or treated with zinc plating, phosphate, or specialty coatings. Pick stainless or high alloy steels for engines facing moisture, road salt, or marine spray, since they resist pitting and stress corrosion. Also choose coatings that match your torque specs so friction stays predictable. Corrosion can cause galling and seizing during disassembly, so use proper lubrication and compatible finishes to keep threads intact and torque accurate. Inspect bolts during rebuilds for rust, coating flake, or thread damage, and replace any showing wear to keep clamp load and safety reliable.
Fitment Compatibility
When you pick main bolts, start with confirming fitment so the fasteners match your engine exactly; this keeps threads, clamping, and clearances correct and gives you confidence during assembly. You should check the kit lists your engine family, block cast codes, or model years so thread pitch, length, and head style are right. Also match bolt counts and locations so inner mains, outer mains, side bolts, and rear cover fasteners aren’t missing. Verify crank journal size and cap configuration, since 2-bolt versus 4-bolt caps and small versus large journals change clamping needs. Check thread form and metric or imperial sizing plus flange versus washered heads to avoid cross-threading. Finally confirm the kit includes windage tray, rear cover, and any extra assembly bolts so mating surfaces get proper matching hardware.
