Chevy V8 Firing Orders: Traditional Small Block vs. Modern LS Patterns
There’s a specific kind of satisfaction that comes from hearing a Chevrolet V8 fire up for the first time after you’ve routed the plug wires yourself. You feel the difference immediately when the engine runs smooth and strong—the lack of vibration changes how you connect with the machine. Knowing the firing order isn’t just for mechanics; it’s the secret language of the engine that keeps everything in perfect rhythm.
TL;DR
Classic Chevrolet small block and big block V8 engines use the traditional firing order 1-8-4-3-6-5-7-2 . The modern LS engine family uses a revised order of 1-8-7-2-6-5-4-3 . GM changed the order to reduce crankshaft stress, improve bearing life, and create a smoother-running engine . This guide shows you both patterns, cylinder numbering, and distributor routing for your Chevy V8.
Key Takeaways
- Classic Chevy V8 (Small Block & Big Block): Firing order is 1-8-4-3-6-5-7-2 . Distributor rotates clockwise .
- Modern LS Engines (Gen III/IV): Firing order is 1-8-7-2-6-5-4-3 .
- Cylinder Numbering: On all Chevy V8s, the driver side (left bank) from front to rear is 1-3-5-7, and the passenger side (right bank) is 2-4-6-8 .
- Why the Change: GM switched the LS firing order to reduce crankshaft torsional vibration and improve bearing durability by about 7% .
Traditional Chevy V8 Firing Order: 1-8-4-3-6-5-7-2
This is the firing order that built the legend. It applies to the classic small block Chevy (265, 283, 302, 305, 327, 350, 400) and the traditional big block Chevy (348, 396, 402, 427, 454) .
How to Route the Spark Plug Wires
Here’s how to get it right on your traditional Chevy V8 with a distributor:
- Find Cylinder #1: Locate the front cylinder on the driver side (left bank) of the engine .
- Set the Distributor: Rotate the engine until the #1 piston is at Top Dead Center (TDC) on the compression stroke. The rotor in the distributor should point toward the #1 spark plug terminal on the cap.
- Follow the Sequence: The distributor rotor spins clockwise . Starting from the #1 terminal, route the plug wires in a clockwise direction following the order: 1-8-4-3-6-5-7-2 .
“Even one wire out of place can cause misfires, backfiring, and rough idle.”
Modern LS Firing Order: 1-8-7-2-6-5-4-3
When Chevrolet introduced the LS engine in 1997, they made a significant change. The new firing order of 1-8-7-2-6-5-4-3 was a departure from the classic pattern .
Why Did Chevrolet Change the Firing Order?
The LS firing order (sometimes called the 4-7/2-3 swap for small blocks) was driven by engineering benefits :
- Less Crankshaft Stress: Computer modeling showed the new order reduced crankshaft torsional vibration and eased bearing loads .
- Improved Durability: The change resulted in a flatter torque curve and increased engine reliability .
- Better Cooling: The traditional order caused cylinders #5 and #7 to fire back-to-back, creating a hot spot in the rear of the engine. The LS order moves adjacent-firing cylinders to the front where coolant is cooler .
Chevy V8 Firing Order Comparison Table
| Engine Family | Firing Order | Cylinder #1 Location | Distributor Rotation |
|---|---|---|---|
| Classic Small Block (283, 327, 350, 400) | 1-8-4-3-6-5-7-2 | Driver side, front | Clockwise |
| Traditional Big Block (396, 427, 454) | 1-8-4-3-6-5-7-2 | Driver side, front | Clockwise |
| Modern LS (LS1-LS7, Vortec Truck) | 1-8-7-2-6-5-4-3 | Driver side, front | Coil-on-plug (no distributor) |
Cylinder Numbering: Finding Your Way Around
Regardless of the firing order, all Chevrolet V8 engines use the same cylinder numbering system :
Driver Side (Left Bank): 1 – 3 – 5 – 7 (front to rear)
Passenger Side (Right Bank): 2 – 4 – 6 – 8 (front to rear)
Front of Vehicle
| |
[1] [2]
[3] [4]
[5] [6]
[7] [8]
Driver Passenger
Side SideTimeline: The Evolution of Chevy V8 Firing Orders
- 1955: The small block Chevy is born with the 1-8-4-3-6-5-7-2 firing order . Big block engines follow the same pattern.
- 1997: The LS1 debuts in the C5 Corvette with the revised firing order 1-8-7-2-6-5-4-3 .
- Early 2000s: The new order expands to all Gen III/IV small blocks and the 8.1L Vortec big block .
- Racing Applications: Pro Stock teams adopt variations like 1-8-7-3-6-5-4-2 for further performance gains .
Frequently Asked Questions (FAQ)
Q: What is the firing order for a 350 Chevy?
A: A classic 350 small block Chevy uses the firing order 1-8-4-3-6-5-7-2 .
Q: What is the firing order for a 454 big block Chevy?
A: The traditional big block Chevy (including the 454) uses 1-8-4-3-6-5-7-2 .
Q: What is the firing order for an LS1 engine?
A: The LS1 uses the modern firing order 1-8-7-2-6-5-4-3 .
Q: Why did Chevy change the firing order on LS engines?
A: To reduce crankshaft vibration, improve bearing life, and create a smoother, more durable engine .
Q: Which side of the engine is cylinder #1 on?
A: On all Chevrolet V8 engines, cylinder #1 is the front cylinder on the driver side (left bank) .
Q: Does the Chevy distributor turn clockwise or counter-clockwise?
A: Traditional Chevy V8 distributors rotate clockwise .
References
Sources and Further Reading:
