There is no universal firing order. It is engine-specific and set by the crankshaft and ignition system arrangement.
The firing order determines the sequence in which cylinders fire and is chosen to balance the engine’s rotating forces, minimize vibrations, and optimize exhaust flow. While many engines follow well-known patterns, the exact order for your model must come from the manufacturer’s specifications or service documentation.
Understanding the concept
Firing order is the planned sequence that delivers spark to each cylinder. It interacts with crankshaft design, cam timing, and ignition architecture (distributor, distributorless, or coil-on-plug). A correct order helps engines run smoothly, start reliably, and avoid damaging misfires or timing-related issues. Because configurations vary widely—from small inline fours to multi-bank V engines—the specifics are always engine-specific.
Common engine configurations
Inline-4 engines are common in compact cars and light trucks. A representative firing order used by many manufacturers is shown below; however, exact sequences can differ by model and year.
- Inline-4 firing order (common example): 1-3-4-2
Note: Some manufacturers use alternative sequences depending on cylinder numbering, crank and cam arrangement, or firing-order balancing. Always verify with the factory documentation for your exact engine.
V8 engines are a staple in performance and full-size vehicles, with several broadly used patterns depending on crank design and bank layout. A widely cited example for many American V8s is listed here.
- V8 firing order (common small-block pattern): 1-8-4-3-6-5-7-2
Variations exist across brands and eras, including cross-plane vs. flat-plane crank designs. The precise order for a given engine can differ, so consult the official service information for accuracy.
How to find your engine’s firing order
To confirm the exact sequence for your engine, follow these steps and rely on official documentation rather than memory or guesswork.
- Check the owner’s manual or the official service manual for the exact firing order for your engine, year, and trim level.
- Determine whether your engine uses a distributor, distributorless ignition, or coil-on-plug to understand how ignition timing is delivered to each cylinder.
- Locate the cylinder identification marks or a diagram on the timing cover or valve cover. This shows which number corresponds to each cylinder.
- Match the firing order to the cylinder numbers using the manufacturer diagram, which indicates ignition sequence and the corresponding spark source.
- If you’re replacing ignition components or timing belts/chains, ensure the new setup aligns with the same firing order; when in doubt, seek professional assistance.
- For distributor-equipped engines, you can use a timing light to verify proper sequence and timing angle as the engine runs.
In short, always verify with OEM materials. An incorrect firing order can cause rough running, misfires, overflow of exhaust, or even engine damage over time.
Summary
The correct firing order is not universal; it depends on the engine’s design and ignition system. Inline-4s commonly use 1-3-4-2 as a representative example, while many V8s use 1-8-4-3-6-5-7-2, among other variations. Always consult your vehicle’s factory documentation or a qualified technician to confirm the exact sequence for your engine model and year.
What is the firing order of 1 6 3 5 2 4?
The firing order is 1,6,3,5,2,4. However, it's better to think of it as 4,1, 6,3, 5,2. Cylinders 4 and 1 share the same crank pin , as does 6 and 3 , and 5 and 2. Number 4 fires 90 degrees before number 1 and so on for the other two pairs.
Why don't cylinders fire in order?
If the cylinders fire in order, it would produce uneven torsional forces on the crankshaft, which may cause it to deform or even break. In addition, because of how much power the firing phase releases, it can stress the engine if the firing occurs simultaneously in adjacent cylinders.
What is the ideal firing order?
Straight-four engines typically use a firing order of 1-3-4-2, however some British engines used a firing order of 1-2-4-3. Flat-four engines typically use a firing order of R1-R2-L1-L2. Straight-five engines typically use a firing order of 1-2-4-5-3, in order to minimise the primary vibration from the rocking couple.
What is 1 8 4 3 6 5 7 2 firing order?
GM V8 Firing Order
The LS engines number the same but changed the firing order. Because of the popularity and longevity of Chevrolet V8 engines, the 1-8-4-3-6-5-7-2 firing order is the one almost every gearhead learns first. These engines came with distributors that spin clockwise, so that's also a useful reference.