454 Chevy belongs to the 4th generation of the big block family of naturally aspirated V8 engines from 1970-1976 and later on as a crate engine. The firing order of this engine is an important design parameter that impacts its smooth operation, vibrations, stress on the crankshaft and bearing, and power and torque delivery.
What is the Firing Order of a 454 Chevy Big Block? The 454 Chevy big block engine has a firing order of 1-8-4-3-6-5-7-2. With 4-7 and 2-3 swap, you can modify it to 1-8-7-2-6-5-4-3 by replacing the compatible camshaft. Other big block engines, including 366, 396, 402, 424, and 502 V8, also share the same firing order as a 454.
We will explain the details regarding the firing order of this engine and its distributor wiring to ensure this sequence. Other related aspects include modification to firing pattern, compatibility with other small and big block Chevy engines, and various sources to find the correct order to ensure efficient engine performance.
Specifications of 454 Chevy Big Block
454 Chevy big block engine has a displacement of 454 cubic inches or 7.4-liter suitable for large torque and power applications. It has 8 cylinders arranged in V-shape in the form of 2 banks oriented at an angle of 90 degrees.
It has an overhead valve (OHV) design, and the valvetrain consists of 2 valves per cylinder with 16 valves. It is available in various GMC and Chevy vehicles from 1970-1976.
Later, the manufacturer introduced a variant of the 454 big block with electronic fuel injection (EFI) from 1987-1990 model years of Chevy C/K pickup trucks.
It has cast iron construction of cylinder head and block, making it heavier, weighing almost 680-690 lbs. The engine has a bore diameter of 4.25 inches, and the stroke length or depth of the borehole is 4 inches for all model years.
Therefore, engine parts are interchangeable between these model years. Its power and torque rating varied for its multiple variants across different model years in the 270-465 hp range and 468-610 lb-ft, respectively.
Later, the manufacturer also introduced a crate version of the engine for power and torque-intensive applications in the latest models.
Cylinder numbering of 454 Chevy Big Block
To understand the firing order, you first need to identify the cylinders. In the Chevy 454 Big Block, the cylinder numbering is in an even-odd arrangement for 2 banks from the front of the engine to the rear.
Standing in its front, numbering follows the sequence 1-3-5-7 on your right or driver’s side of the vehicle. The 2nd bank on the passenger’s side has a pattern of 2-4-6-8 from front to back.
Considering the above, cylinder #1 is on the driver’s side closest to the front of the vehicle, while the last cylinder #8 is on the passenger side farthest from you.
Moreover, it is imperative to follow the convention of standing in front of the engine or vehicle while starting the numbering.
Firing order of 454 Chevy Big Block
The firing order of a 454 Chevy Big Block is a precise sequence that dictates when each cylinder receives a spark to ignite the air-fuel mixture. Using the cylinder numbering of the engine, the firing pattern is 1-8-4-3-6-5-7-2.
It means that ignition starts in cylinder #1, then cylinder #8 on the 2nd bank, followed by cylinder #4 on the 1st bank, and then cylinder #3. The next cylinders in the order are 6, 5, and 7; cylinder #2 is the last to complete the cycle.
Experts recommend keeping the firing order of the engine in such an order that no two adjacent spark plugs in the opposite banks ignite consecutively. It is imperative to ensure smooth power delivery, reduce engine vibration, and optimize torque characteristics.
Failing to do so increases the chances of vibration and misfiring. Its firing order has that issue of consecutive spark plugs firing in opposite banks, causing vibration and loss of power in engine operation. Proper sequencing of ignition events contributes to the engine’s overall performance and smooth operation.
Distributor wiring for correct firing order of Chevy 454 engine
The distributor has the purpose of delivering the current to spark plugs in every cylinder in the correct order to start ignition. It has 8 connection points and a rotating arm on its cap that moves clockwise, changing the connection with each cylinder according to firing order.
To achieve the firing order of 1-8-4-3-6-5-7-2, you should wire the distributor cap with each spark plug accordingly. You will connect the starting point on the distributor cap with cylinder #1.
The following connection will be with the spark plug on cylinder #8, then cylinder #4, and so on, according to the 1-8-4-3-6-5-7-2, traversing the distributor cap clockwise.
It is pertinent to mention that the rotation direction in Chevy big block engines differs from Ford big block engines, where distributor caps move counterclockwise.
However, its latest models have distributorless ignition systems where direct signals from the control module ensure the firing sequence.
Do all Chevy vehicles having 454 big block engines have the same firing order?
Chevy big block 454 engine is available in various models, including cars, sports cars, and small pickup vehicles from 1970-1976.
A few examples are the Chevrolet Corvette from 1970-1974, the GMC Sprint from 1971-1975, the Chevy Caprice from 1970-1976, and the Chevy El Camino pickup from 1970-1975 model years.
This firing order is a fundamental parameter related to the engine design and remains consistent regardless of the specific vehicle model or application. Therefore, you will find the same sequence of 1-8-4-3-6-5-7-2 across all Chevy vehicle models equipped with a 454 Big Block engine.
There can be a difference in the orientation or position of the engine under the hood. Therefore, you have to ensure the convention of standing in its front while tracing cylinder numbering, whether it is in a horizontal or vertical position with respect to the vehicle body.
Other Chevy big block engines have the same firing order as the 454 engine
Manufacturers keep the firing order consistent for various engines belonging to the same family, as it is a design parameter to ensure smooth operation without excessive vibrations.
Therefore, several other Chevy big block engines share the same firing order as the 454. Other examples sharing the same firing order of 1-8-4-3-6-5-7-2 are big block 366 (6.0-liter) V8, 396 (6.5-liter), and 402 (6.6-liter) V8 engines.
Furthermore, the Chevy 424 big block or 7.0-liter V8 from the Mark IV family and the 502 (8.2-liter) V8 from the 5th generation of Chevy engines also share the firing order with the 454 engine.
Chevy Small block engines have the same firing order as the 454 engine
Chevy big and small block engines have different design characteristics and specifications, including power and torque ratings and physical dimensions. However, some V8 engines from the small block family share the 1-8-4-3-6-5-7-2 firing order with the 454 V8 engine.
Some earlier models of small block V8, including 307 (5.0-liter), 327 (5.4-liter), 350 (5.7-liter), 265 (4.3-liter), and 283 (4.6-liter) V8 engines, had this firing order until Chevy introduced the modified sequence of 1-8-7-2-6-5-4-3 or 1-8-7-3-6-5-4-2 in these models. The Chevy 400 (6.6-liter V8) small block also has the same firing order as the 454 big block engine.
Can we change the firing order of the big block Chevy 454 V8 engine?
The engine’s camshaft decides the valve’s opening according to firing order and has synchronization with the spark plugs firing to start ignition.
Therefore, changing the firing sequence of a Chevy 454 engine requires a change in camshaft design to operate the valves according to the modified order and subsequent modification in the distributor wiring pattern.
One possible alteration many people do is swapping cylinder #7 and 4 in the sequence. Another possible change is swapping cylinder #2 and 3. After a 4-7 swap, the new firing order becomes 1-8-7-3-6-5-4-2, and after a 2-3 changeover, it becomes 1-8-7-2-6-5-4-3.
The manufacturer has proposed this modification after computer simulations and claims it reduces 7% stress on the bearing and crankshaft, resulting in a better torque curve and smoother engine operation due to reduced vibration and wear and tear.
According to the modified sequence, Camshafts are available from various third-party manufacturers. You can install the one to get the benefits Chevrolet and General Motors claimed.
Where to find the firing order of the Chevy 454 big block?
You can find the firing order using various sources. The first and foremost location to look for this information is in the vehicle’s service manual or engine specifications documentation provided by the manufacturer.
Additionally, numerous online resources, automotive forums, and reference books dedicated to Chevy engines are available to assist in locating the firing order for the Chevy 7.4-liter V8.
You can also note it by manually moving the machine by tracking the position of the top dead center (TDC) of each cylinder and the connection point of its spark plug on the distributor. Authorized Chevrolet or General Motor dealers also have this information according to the model year of your vehicle.