How many head bolts does a SBC 350 have?
The SBC 350 has eight head bolts in total—four securing each cylinder head.
This article explains the standard fastener count for Chevrolet’s small-block 350 V8, how the bolts are arranged, and what to know if you’re rebuilding or modifying an engine. While eight bolts is the norm, certain aftermarket or performance builds may use alternative fasteners, so always verify with the specific engine manual for your block and head combination.
Head bolt count and layout
The standard small-block Chevy 350 uses a straightforward configuration: one cylinder head on each side, each secured by four bolts, for a total of eight fasteners. This arrangement has been consistent across generations of the Gen I SBC family and is a familiar feature for restoration and rebuild work.
Below is a quick outline of the head bolt count and arrangement on a typical SBC 350.
- Total head bolts: 8 (4 per cylinder head).
- Arrangement: four bolts secure each head to the engine block, typically distributed around the head’s perimeter to clamp the head evenly against the gasket.
- Variations: some high-performance builds may use head studs or alternate fastener configurations; always confirm the exact type for your engine and read the factory service manual for torque and sequence.
Concluding the list: the standard SBC 350 uses eight head bolts, with four per head. If you’re rebuilding or upgrading, reference the engine’s manual to ensure you use the correct fasteners and torque pattern for your specific block and heads.
Notes for builders and restorers
In practice, most stock and restored SBC 350 applications rely on eight bolts. Some aftermarket setups replace bolts with studs for convenience or strength, which changes installation procedures but not the basic total count. Always verify your exact engine variant and follow the recommended torque sequence and values from the manufacturer.
Summary
Are SBC head bolts tty?
No. SBC head bolts are not torque to yield meaning torqued until the bolt stretches. SBC head bolts are meant to be set at one final torque that is 65 ft pounds. Apply some anti-seize to the threads on each bolt.
What does 4 bolt main mean on a 350?
Blocks. That's in reference to the main caps. And the number of bolts holding them to the block. There's a lot of force trying to push the crankshaft out of the bottom of the engine.
What is the difference between 2 bolt and 4 bolt SBC?
A SBC (small-block Chevrolet) 2-bolt engine is for lighter-duty street use, typically under 400 horsepower, while a 4-bolt engine is stronger and better for high-performance applications like racing, forced induction, or nitrous, as it provides more clamping force to the crankshaft's main bearings. The key difference is the number of bolts per main cap: 2 bolts for a 2-bolt, and 4 bolts (two per side) for a 4-bolt, making the 4-bolt block more robust against the high forces generated by powerful engines.
This video explains the difference between SBC 2 bolt and 4 bolt engines: 57sSpeedway MotorsYouTube · Apr 1, 2024
2-bolt main blocks
- Best for: Standard street applications, typically up to 400 horsepower.
- Mechanism: Each main cap is secured to the engine block with two bolts, one on each side.
- Strength: Sufficient for most street builds, especially when using upgraded main studs, but more susceptible to "cap walk" under high stress.
4-bolt main blocks
- Best for: High-horsepower builds, forced induction (turbochargers, superchargers), and nitrous applications.
- Mechanism: Each main cap has four bolts—two on each side—which provides greater clamping force and strength.
- Strength: More durable and resistant to flexing, preventing the main caps from moving under extreme load.
This video shows how to identify a 4 bolt Chevy engine: 55sThe Gas HouseYouTube · Jan 28, 2023
Other considerations
- Splayed 4-bolt caps: A stronger variation where the outer bolts are angled outward for even more strength and are recommended for extreme applications.
- Upgrades: A 2-bolt block can be upgraded with aftermarket main studs to be more robust, sometimes making it comparable to a 4-bolt with factory bolts.
- Engine block variants: Not all 4-bolt blocks are equally strong. For example, some 400 small block Chevy blocks are known to be weaker in certain areas, and aftermarket blocks are a popular choice for extreme power goals.
Are Chevy 350 head bolts reusable?
The answer is yes, but only if the replacement head bolt meets the grade of the correct head bolts.
