Ford 351 Cleveland (351C) is a V8 engine manufactured at the Cleveland plant from 1970-1974. Understanding the firing order of the 351 Cleveland is essential to ensure its vibration less, smoother operation, and balanced power output.
What is the Firing Order of a 351 Cleveland? 351 Cleveland has 8 cylinders having 1-3-7-2-6-5-4-8 firing order. Its distributor rotates in an anticlockwise direction, having wiring to spark plugs according to this pattern. All variants, including 351C-2V, 351C-4V, 351C Cobra Jet, and Boss 351, also have the same firing order. Other engines like Ford 5.0 HO EFI, 5.4-liter, and 4.6-liter V8 also share the same sequence.
Due to its high power output and robust design, it remained the heart of the Ford and Mercury muscle car lineup. We will also discuss its cylinder numbering, its different variants, and the effect of a camshaft on its firing order.
Engines in 351 Cleveland family
The 351 Cleveland (351C) belongs to the Ford 335 series of engines, featuring several variants, each with unique specifications and characteristics.
It includes the 2V version from 1970-1974, featuring a 2-barrel carburetor named H-code, and the 4V variant available from 1970-1971, equipped with a 4-barrel carburetor called as M-code.
Both engines have remarkable power output for small to full-size cars. The 351 Cobra Jet (CJ) Q-Code variant available from 1971-1974 stands out with improved cylinder heads, a special intake manifold, and other enhancements for increased performance.
You will find it in muscle cars like the Ford Mustang Mach 1, Ford Torino, and Mercury Montego. The Cleveland 351 Boss (R-Code) boasts a specially tuned camshaft, high-flow cylinder heads, and a robust build designed primarily for racing applications in cars like the Ford Mustang Boss 351.
On the other hand, the 351 Modified (M) introduced in 1975 is an entirely different engine designed for lower emissions and improved fuel efficiency.
Lastly, the 400 Modified (M) also belongs to the 335 series and has similarities with the 351M variant, but it offers a larger displacement, resulting in increased torque and low-end power.
Cylinder numbering of Ford 351 Cleveland engine
The cylinder numbering of the Ford 351 Cleveland follows a standard pattern common in many V8 engines. It is essential to know this numbering scheme to find the firing order of these engines.
It has 8 cylinders arranged in a V-shape in 2 banks. The cylinders on the passenger side, starting from the front closest to the radiator of the vehicle, have numbers 1, 2, 3, and 4.
On the other hand, the cylinders on the driver’s side of the engine, also from the front to back, are numbered 5, 6, 7, and 8.
This numbering system applies to both the 2V and 4V types, including H, M, R, and Q code variants of the 351 Cleveland engine. It is crucial to have this knowledge when setting the firing order and performing any maintenance or repairs on your Ford or Mercury vehicles.
Firing order of different variants of 351 Cleveland
This firing order is a fundamental aspect of the engine’s design and is the same across all variants of Ford 351 Cleveland engines.
The designer decides it after thorough analysis to ensure smooth, efficient, and balanced engine performance with no vibrations.
It has a firing order of 1-3-7-2-6-5-4-8. It means that the spark plug fires in this sequence, and valves open accordingly to start ignition.
Camshaft and valve timing play a crucial role in maintaining this order. This sequence is the same across different variants of 351 Cleveland, including the 2V, 4V, Cobra Jet (CJ), and Boss 351.
It is a modified sequence after Ford changed it from earlier V8 engines using a revised camshaft to gain some improvement in power output.
Do Ford 351 Cleveland and its modified version have the same firing order?
The Ford 351 Cleveland and its modified versions, such as the 351M and the 400, share the same firing order. All 3 are V8 engines having 8 cylinders and the same numbering pattern.
Therefore, you will find it in the sequence 1, 3, 7, 2, 6, 5, 4, 8, which is exactly the same as that of the 351C engine. While there are differences in other specifications, such as engine parts and power output, the firing order remains the same.
This consistency allows for the use of similar ignition systems and distributor wiring. Moreover, it is helpful for owners and mechanics to troubleshoot the misfiring problems and resolve any issues regarding the ignition timing.
Direction of distributor rotation on Ford 351 engine
The direction of distributor rotation on a Ford 351 engine is counterclockwise. It is essential in determining the firing order and the proper timing of spark events.
As the distributor rotor turns counterclockwise, it aligns with each spark plug wire terminal in its cap at precisely the right moment, based on the engine’s timing specifications. Its wiring connects with the spark plug wires with the distributor cap to match the firing order.
Therefore, you should start by attaching the spark plug wire for cylinder #1 to the terminal on the distributor cap that corresponds to cylinder #1.
Then, follow the order 1-3-7-2-6-5-4-8 for the 351 Cleveland as you connect each spark plug wire to its respective terminal in a counterclockwise direction.
Engines having the same firing order as Ford 351 Cleveland
Several V8 engines have the same firing order as this 351C engine. Ford 5.0 HO EFI and 5.8-liter V8 have the 1-3-7-2-6-5-4-8 firing order and identical distributor wiring to achieve this pattern to ensure smoother engine operation.
Ford 5.4-liter V8 Triton engines also have the same sequence for spark plug ignition despite belonging to a different lineup and having dissimilar specifications.
Additionally, Ford’s 4.6-liter V8 from 1990-2014 employed this firing order in all their applications for smoother performance and better fuel distribution.
Beyond Ford, custom engine builders and racers adopt this firing order in various racing and high-performance applications because of balanced power output.
Do all vehicles having 351 Cleveland engines have the same firing order?
Different variants of 351 Cleveland have been part of various Ford vehicles requiring high-performance engines from 1970-1974. It includes cars like the Ford Mustang, Ford Torino, Mercury Cougar, and Mercury Montego.
You will also find its applications in pickup trucks like the 1974 Ford Ranchero. Despite different power outputs and some upgrades in various model years, the firing order of 351 Cleveland is consistent across all versions and vehicle applications.
You will find the same 1-3-7-2-6-5-4-8 firing order in all these automobiles because Ford has designed it after various simulations to provide balanced operation with high-performance results.
Effect of camshaft on firing order of 351 Cleveland engine
The camshaft has a lobe for each intake and exhaust valve in the engine. The lobes open and close the valves at the appropriate times during the combustion cycle. The camshaft is also responsible for driving the distributor, which manages the ignition to the spark plugs.
If you replace the camshaft with a different one, the lobes will differ in shape or size. It changes the timing of the valve opening and closing events. It can also vary the timing of the spark, resulting in different firing order of the engine.
For example, a racing camshaft has more aggressive lobes that open the valves wider and longer. It increases the airflow and fuel flow into the cylinders, which can increase power.
However, it also affects the firing order, and you need to make regressive adjustments to avoid engine failure to start or misfiring problems.
How do we set the firing order of a 351 Cleveland?
If a 351 Cleveland engine has a misfiring problem or is not starting, you can rectify its firing order by manually rotating the crankshaft.
The first step is to locate the rotor by removing the distributor cap. Next, turn the crankshaft until the cylinder #1 piston is at the top of its compression stroke. I did this by removing the spark plug from this cylinder and inserting a long rod into the spark plug hole.
Turn the crankshaft until the piston reaches the top of its stroke and the screwdriver or rod stops moving. Align the rotor with the spark plug #1 wire on the distributor cap. Lastly, install the distributor cap and tighten the screws.
You should also check that all 8 spark plugs are connected with the distributor according to 1-3-7-2-6-5-4-8 firing order in counterclockwise direction. Moreover, you should avoid twisting any two spark plug wires to prevent their simultaneous ignition.