The firing order for a small block 350 Chevrolet engine is 1-8-4-3-6-5-7-2

This sequence tells you the order in which each cylinder fires, starting from cylinder 1 and moving around the engine block. The small block 350 is a V8 engine with eight cylinders arranged in two banks of four. Cylinder 1 is the front-left cylinder on the driver's side, and the numbering continues down that bank, then across to the passenger side.

The firing order matters because it determines how you route the spark plug wires from the distributor cap to each spark plug. If the wires are in the wrong order, the engine will misfire, run rough, or not start at all. Getting this sequence right is one of the first steps when you're rebuilding an engine, replacing a distributor, or troubleshooting ignition problems.

Key Takeaways

  • The firing order 1-8-4-3-6-5-7-2 is the standard sequence for all small block 350 engines, whether carbureted or fuel-injected.
  • Cylinder 1 is always the front-left cylinder on the driver's side, and numbering runs front-to-back on each bank.
  • The distributor rotor turns in a specific direction, and the spark plug wires must follow the firing order around the distributor cap in that same direction.
  • Swapping even two wires will cause the engine to run poorly or not run at all, so double-check your work before starting the engine.

How cylinder numbering works on the 350

The small block 350 has two cylinder banks: the driver's side (left) and the passenger's side (right). On the driver's side, cylinders are numbered 1, 2, 3, and 4 from front to back. On the passenger's side, cylinders are numbered 5, 6, 7, and 8, also from front to back.

The front of the engine is the end closest to the radiator and the crankshaft pulley. If you're standing in front of the engine looking back at it, cylinder 1 is on your left. This numbering is consistent across all Chevrolet small block engines, including the 327, 305, and 400, so if you've worked on another small block, you already know where to find cylinder 1.

Understanding the distributor cap and rotor

The distributor cap has eight terminals arranged in a circle, one for each cylinder. The rotor inside the cap spins and points to each terminal in sequence as the engine runs. The rotor turns clockwise on most small block 350 engines, though some high-performance or modified distributors may turn counterclockwise, so you need to verify which direction yours spins.

When you install spark plug wires, you route them from the distributor cap terminals to the spark plugs in the order the rotor will reach them. If the rotor spins clockwise, you start at one terminal and move clockwise around the cap, placing wires in the firing order sequence. The wire from the number 1 terminal goes to the number 1 spark plug, the wire from the number 8 terminal goes to the number 8 spark plug, and so on.

Steps for routing spark plug wires correctly

Start by locating the number 1 terminal on the distributor cap. Most caps have a small notch, mark, or raised bump at the number 1 position. If yours doesn't, you can find it by removing the cap and watching where the rotor points when the engine is at top dead center on cylinder 1. The rotor should point directly at the number 1 terminal.

Once you've identified the number 1 terminal, write down or mark the positions of all eight terminals going around the cap in the direction the rotor spins. Then, using the firing order 1-8-4-3-6-5-7-2, route the wires in that sequence. The wire from terminal 1 goes to cylinder 1, the wire from terminal 8 goes to cylinder 8, the wire from terminal 4 goes to cylinder 4, and so on. Take your time and double-check each wire before you start the engine.

Common mistakes when setting firing order

The most frequent error is reversing the direction. If you route the wires counterclockwise when the rotor spins clockwise, every wire will be one position off, and the engine won't start. Another common mistake is confusing cylinder location with terminal position on the cap. The terminals are arranged in a circle, but the cylinders are arranged in two banks, so the physical layout of the cylinders doesn't match the layout of the cap terminals.

A third mistake is assuming all distributors have the same rotor direction. While most small block 350 distributors spin clockwise, some aftermarket or performance distributors spin the opposite way. If you're using a distributor you're unfamiliar with, verify the rotor direction before you install the wires. You can do this by removing the cap and turning the engine by hand with a wrench on the crankshaft pulley, watching which way the rotor spins.

What to do if you've already installed the wires wrong

If the engine won't start or runs very rough, the first step is to remove the distributor cap and check the wire routing. Compare what you see to the firing order sequence. If even one wire is out of place, move it to the correct terminal. If multiple wires are wrong, you may have reversed the entire sequence, which means you need to reroute all of them.

If you're not sure which wires are in the wrong position, remove all of them and start over. Mark each wire with a piece of tape showing which cylinder it came from, then lay them out in order before reinstalling them. This method takes longer but eliminates confusion and prevents you from making the same mistake twice.

Firing order for other small block Chevrolet engines

The firing order 1-8-4-3-6-5-7-2 applies to the 350, but also to the 327, 305, and 400 small block engines. All of these engines use the same cylinder numbering and the same firing sequence. If you're working on a different Chevrolet engine, such as a big block or an inline six-cylinder, the firing order will be different, so verify the correct sequence before you start.

The firing order also doesn't change based on whether the engine is carbureted or fuel-injected. A 350 with a carburetor and a 350 with fuel injection both use 1-8-4-3-6-5-7-2. The fuel injection system controls when the injectors spray fuel, but the spark plugs still fire in the same order.

Frequently Asked Questions

What happens if I install the spark plug wires in the wrong order?

The engine will either not start or run very rough with severe misfires. You may also see backfiring through the carburetor or exhaust. The wrong firing order prevents the cylinders from firing in the sequence the engine was designed for, so combustion becomes chaotic and the engine can't run smoothly or at all.

Can I use the firing order from a different engine in my 350?

No. Each engine design has its own firing order based on how the crankshaft is configured. Using the wrong firing order will prevent the engine from running. Always verify the correct sequence for your specific engine before installing wires.

Does the firing order change if I modify the distributor?

The firing order itself doesn't change, but the rotor direction might. Some high-performance distributors are built to spin counterclockwise instead of clockwise. If you swap distributors, verify which direction the rotor spins before you route the wires, because the direction determines whether you go clockwise or counterclockwise around the cap.

How do I know which terminal is number 1 on my distributor cap?

Most caps have a notch, mark, or raised bump at the number 1 position. If yours doesn't, remove the cap and rotate the engine by hand until the rotor points straight up. Check your engine manual to see which cylinder should be at top dead center at that moment, then mark that terminal as number 1.

Can I test the firing order without starting the engine?

Yes. Remove the distributor cap and rotate the engine by hand with a wrench on the crankshaft pulley. Watch the rotor point to each terminal in sequence and verify it matches the firing order 1-8-4-3-6-5-7-2. This method lets you catch mistakes before you try to start the engine.