Your Chevy vehicle actually has a sequence for the spark plugs firing mechanism. This is called your engine firing order. If the engine is equipped with a distributor, the firing order is usually determined by the spark plug wires routing that connects the distributor cap to each cylinder’s spark plugs. If the piston placement uses the top dead center (TDC) positioning on the compression stroke, then you can be sure that the distributor rotor is aligned with the spark plug terminal #1 in the distributor cap. The next firing sequence will normally go to the next plug wire in the cap, depending on which way the distributor rotates. It might rotate clockwise or anti-clockwise, following the design from the manufacturer.
If your Chevy vehicle is a rear-wheel drive car or a truck type, then the #1 cylinder is usually the first cylinder located on the left front side of the vehicle. Meanwhile, the #1 cylinder can be found on the right front side of the car on Chevy vehicles that are either front-wheel drive cars or traverse V6-mounted minivans.
The sequence for the cylinders goes from side to side, beginning on the #1 cylinder and going all the way to the back of the engine. The bank cylinders on the left side of the V6 or V8 engine will be odd-numbered, while the other side will be even-numbered. This also applies to the traverse V6-mounted Chevy vehicles.
Chevy V8 Firing Orders
On Small Block V8 engines produced by Chevy with model numbers 265, 283, 302, 327, 350, or 400, the firing order goes as 1-8-4-3-6-5-7-2.
On Big Block V8 engines produced by Chevy with model numbers 396, 406, 427, or 454, the firing order is also 1-8-4-3-6-5-7-2.
Meanwhile, the firing order is 1-8-7-2-6-5-4-3 for Chevy engines with LS designs, including LS1 through LS7.
NOTE: The firing sequences above are usually typical for crankshaft with standard cross-plane design with the positioning of the throws are spaced 90 degrees apart.
Changing the Firing Order
The firing sequence can be altered by users, especially on cars with special racing camshafts. On V8 engines with Small Block and Big Block design, the firing order can be altered by changing the order of cylinders 4 and 7. As a result, the new order will be 1-8-7-3-6-5-4-2. This alteration can actually improve the air/fuel distribution, especially cylinders that are recently changed. The result from this is that the engine will be more effective in reducing heat buildup and the engine can be easier to tune. Drivers might also notice reduced vibrations and torsional loads.
Chevy Marine Engine Firing Orders
The firing order is typically the same for the Chevy V8 marine engine built with a standard rotation design. A reverse direction might be found on boats that feature twin inboard engines, which is used to offset the opposite engine’s rotational effects. This mechanism will help the boat to get more stable. This type of engine will also feature a special marine camshaft that can change the timing for the valve, which will rotate in a different direction.
The reverse firing order for the Chevy marine engine is 1-2-7-5-6-3-4-8.
Why Firing Order Matters
It is necessary to get the firing order in a correct sequence because the engine might have difficulty starting if the spark plug wires get mixed up. The engine could also experience backfiring, and the performance would get worse than normal.
Watch Out for Ignition Crossfire
Crossfire can also happen on engines that feature a design where two adjacent spark plugs are located next to each other. You will need to make sure that the wires are not routed on those spark plugs, especially for long-distance connections. The crossfire between those plugs will create a magnetic field, which may also cause one of the plugs to fire prematurely. The engine will run rough, and misfiring will occur. You can cancel out the possibility of crossfire by using a crisscross design for the adjacent spark plugs wires.
If you have engines built with ignition systems that have no distributor, the firing sequence is usually determined by the engine computer or the ignition module. The engine computer will process a signal sent by the camshaft or crankshaft position sensor, and it will determine the right piston on the top dead center location of the compression stroke. The spark plug firing order will be then activated, which fires the plugs from the first to the last one.