The 350 Small Block Chevy fires cylinders in the order 1-8-4-3-6-5-7-2
The firing order is the sequence in which the spark plugs ignite the fuel mixture in each cylinder. For a 350 small block Chevrolet engine, that sequence is 1-8-4-3-6-5-7-2. This order matters because it determines how you route the spark plug wires from the distributor cap to each cylinder, and getting it wrong will prevent the engine from running or cause severe misfiring and damage.
The cylinders are numbered 1 through 8. On a small block Chevy, cylinders 1, 2, 3, and 4 are on the driver's side (left bank), and cylinders 5, 6, 7, and 8 are on the passenger's side (right bank). Cylinder 1 is always at the front of the engine on the driver's side. The firing order ensures that the crankshaft's rotation and piston position align with spark delivery so combustion happens at the right moment in each cylinder's cycle.
Key Takeaways
- The 350 small block Chevy firing order is 1-8-4-3-6-5-7-2, and this applies to all standard 350 engines regardless of year or process.
- Cylinders 1, 2, 3, and 4 are on the driver's side; cylinders 5, 6, 7, and 8 are on the passenger's side, with cylinder 1 at the front.
- Spark plug wires must follow the firing order from the distributor cap to avoid misfiring, rough idle, and engine damage.
- The distributor cap has numbered terminals that correspond to cylinder positions, and the rotor points to each terminal in firing order as the distributor shaft turns.
How the Distributor Cap Terminals Are Arranged
The distributor cap on a 350 small block Chevy has eight terminals arranged in a circle. Each terminal connects to one cylinder via a spark plug wire. The terminals are numbered 1 through 8, and they are positioned around the cap in a specific layout that matches the engine's cylinder arrangement.
On most 350 small block distributors, terminal 1 is located at the front of the cap (toward the radiator), and the remaining terminals are arranged clockwise around the cap. The exact position of terminal 1 can vary slightly depending on the distributor manufacturer and year, so always check the cap itself or the engine block for a diagram before routing wires. The rotor inside the distributor spins and points to each terminal in sequence as the engine runs, delivering spark at the precise moment each cylinder needs it.
Routing Spark Plug Wires in the Correct Order
To route spark plug wires correctly, start by identifying which terminal on the distributor cap connects to cylinder 1. This is usually marked on the cap itself with a small "1" or an arrow pointing to the front of the engine. From that terminal, follow the firing order 1-8-4-3-6-5-7-2 around the cap, moving clockwise or counterclockwise depending on the distributor's rotation direction.
For a 350 small block Chevy with a standard clockwise-rotating distributor, you would route wires in this pattern: terminal 1 to cylinder 1, then the next terminal clockwise to cylinder 8, then the next to cylinder 4, and so on. If your distributor rotates counterclockwise, the pattern reverses. The spark plug wires themselves should be routed away from hot engine surfaces and other electrical components to prevent cross-firing or insulation damage. Use wire holders or clips to keep them organized and separated.
Common Mistakes When Installing Spark Plug Wires
The most frequent error is installing wires in numerical order (1-2-3-4-5-6-7-8) instead of the correct firing order. This happens because it seems logical, but it will cause the engine to misfire severely or not start at all. Another common mistake is confusing the cylinder numbering on the engine block with the terminal numbering on the distributor cap—they are not always the same.
A third error occurs when swapping distributors or rebuilding the engine: the new distributor may have a different rotation direction or terminal layout than the original. Always verify the firing order and terminal positions before connecting wires. If you install wires incorrectly and the engine runs but misfires, rough idles, or loses power, stop when ready and recheck the wire routing. Running an engine with incorrect firing order can damage the catalytic converter and cause internal engine wear.
Checking Your Work Before Starting the Engine
Before you start the engine, trace each spark plug wire from the distributor cap to its corresponding spark plug. Write down which terminal the wire comes from and which cylinder it goes to, then compare your list to the firing order 1-8-4-3-6-5-7-2. If any wire is out of sequence, move it to the correct terminal.
You can also verify the firing order by rotating the engine by hand using a wrench on the crankshaft bolt while watching the rotor inside the distributor. As you turn the crank clockwise (when viewed from the front), the rotor should point to each terminal in the correct sequence. If it does not, the distributor may be installed 180 degrees out of phase, which requires removing and reinstalling it. Take the time to verify before starting; it takes 15 minutes and prevents hours of troubleshooting.
Firing Order for Modified or Aftermarket 350 Engines
The firing order 1-8-4-3-6-5-7-2 is universal for all 350 small block Chevy engines, including those with aftermarket heads, intake manifolds, or internal modifications. The firing order is determined by the crankshaft design and cylinder arrangement, not by performance upgrades. However, if you are using an aftermarket or high-performance distributor, verify that the terminal layout matches the standard 350 configuration.
Some vintage or specialty distributors may have different terminal positions or rotation directions. If you are unsure, contact the distributor manufacturer or consult the documentation that came with it. The firing order itself never changes, but how you route the wires to the distributor cap may vary depending on the specific distributor model you are using.
Frequently Asked Questions
What happens if I install the spark plug wires in the wrong order?
The engine will misfire, run very rough, or not start at all. If it does run, it will lose power, idle poorly, and may damage the catalytic converter. Stop and recheck the wire routing when ready.
Does the firing order change if I use a different distributor?
No. The firing order is always 1-8-4-3-6-5-7-2 for a 350 small block Chevy. However, the terminal positions on the distributor cap may vary, so you must verify the cap layout before routing wires.
How do I know which end of the engine is the front?
The front of the engine is the end closest to the radiator and the front of the vehicle. Cylinder 1 is always at the front on the driver's side. If you are unsure, check the engine block for a casting number or diagram.
Can I use the firing order to time the engine?
No. Firing order tells you the sequence of spark delivery, not the timing. Timing is set separately using a timing light and the timing marks on the crankshaft pulley and engine block.
What if my distributor cap does not have numbers marked on it?
Check the engine block or the original documentation for the cap layout. You can also contact the distributor manufacturer with the part number. Never guess—an incorrect wire routing will damage the engine.