1342 is a common firing order for inline-four engines because it spaces the ignition events to distribute power evenly, helping balance the crankshaft and reduce vibration, while aligning with traditional ignition layouts. Not all engines use this sequence, but it is widely adopted for its smoothness and simplicity.
Understanding firing orders
Firing order is the sequence in which the cylinders fire during each four-stroke cycle. The choice of order affects vibration, torque delivery, exhaust scavenging, and how the ignition system must be wired or routed. For four-cylinder engines, manufacturers select a sequence that balances the rotating forces and matches the physical layout of the crank, camshaft, and ignition components.
Crank and cam timing basics
In a four-stroke inline engine, each cylinder fires once every two crank revolutions. The crankshaft’s throw positions and the order in which cylinders are positioned around the crank determine which cylinder fires next. The firing order must accommodate valve timing (whether the engine has a single camshaft or dual camshafts), as well as the ignition system layout (points, distributor, or coil-on-plug arrangements). These mechanical constraints help explain why 1342 shows up so frequently on many designs.
Why 1-3-4-2 works well for many inline-fours
The 1-3-4-2 sequence is favored because it tends to distribute power strokes around the crankshaft in a way that smooths out torque fluctuations. By spacing the fires so that opposing or nearby cylinders do not all fire in quick succession, the engine experiences less torsional stress and fewer vibrations. This ordering also aligns conveniently with the common position of cylinders and the way ignition components were traditionally wired or packaged, making it a practical standard for maintenance and service. Additionally, the exhaust pulses from the fired cylinders arrive at the exhaust manifold in a pattern that can be scavenged more effectively, helping both performance and efficiency in many designs.
In practice, the exact firing order is dictated by the engine’s crank throw geometry, valve timing, and ignition architecture. The 1-3-4-2 order is not universal; some engines use 1-4-2-3 or 1-2-4-3, depending on how their internals are arranged and what engineers deemed best for balance and response.
Alternative firing orders and when they appear
Other firing orders exist for inline-four engines, chosen to optimize balance, vibration, or packaging for specific engine layouts or performance goals. The following examples illustrate the variety and why different manufacturers might prefer alternatives to 1342.
- 1-4-2-3: Used by some designs where valve timing or exhaust routing favors this spacing to improve throttle response or torque delivery in certain RPM ranges.
- 1-2-4-3: Another common alternative that can better suit particular crankshaft throws or distributor/coil layouts in specific engines.
- Other minor variations: A few engines swap adjacent cylinder numbers or adjust timing slightly to accommodate unique cam phasing or exhaust manifold designs.
Regardless of the exact sequence, the key goal remains the same: minimize vibration and uneven torque while matching the engine’s mechanical and ignition architecture. Changing firing order in a production engine requires extensive redesign and retooling, so the chosen order tends to be stable within a given family.
Summary
1342 is a widely used firing order for inline-four engines because it provides smooth torque distribution, helps reduce crankshaft vibration, and aligns with traditional ignition and exhaust layouts. While it is common, it is not universal; other engines may adopt 1-4-2-3 or 1-2-4-3 depending on their specific crank geometry, valve timing, and ignition system design. Understanding firing order helps with diagnosing misfires, tuning, and appreciating how engine design influences performance and reliability.