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What is the Ford Firing Order, and Why is This Important?
The standard order for the spark plug firing is 1-5-4-2-6-3-7-8. Now, it is essential to note that Ford did not use this firing order for every V8 engine it produced. Restorers should double-check the firing order for the specific engine in their vehicles before attempting to work on them.
The firing order refers to the order in which the spark plugs fire. In a V8, the cylinders are arranged in two banks on either side of the engine. Facing the engine, the cylinders numbered 1 - 4 are located on the right (driver's) side, beginning with 1 being the closest cylinder to the front. Cylinders 5 - 8 are located on the left side, with number 5 being closest to the front of the car.
As each piston rotates, the spark plug is triggered to fire. This spark ignites the mixture of air and fuel inside the engine. The explosion fills the chamber with exhaust, forcing the piston back down and allowing the next cylinder to rotate the piston up and fire. All eight cylinders follow in their designated firing order until the order repeats with cylinder 1.
The goal is to compress what fuel/air mixture so that when the spark plug fires, it produces the maximum combustion needed to power the wheels.
In addition, the correct firing order allows for the minimum vibration of the engine and tends to make the ride smoother. As any car enthusiast knows, the less an engine vibrates, the less strain is required for the engine to operate, which extends the life of the motor and improves the fuel economy.
What is the Firing Order for Other Ford Engines?
Because it was designed to be a high-performance engine, specifically for the BOSS Mustang, the HO 302 engine differed substantially from the non-HO. It is essential to know if your vehicle’s engine is a high-performance V8 or not. The firing order for both engines is listed below.
- HO Ford 302 engine (351 ci): 1-3-7-2-6-5-4-8
- Non-HO Ford 302 engine: 1-5-4-2-6-3-7-8
How does the Spark Plug Know when to Fire?
Each plug fires from wires that run from the plug to the distributor cap. On top of the cap are connections for the wires, one designated for each cylinder. Inside the distributor, rotors spin
And as the tip of the rotor passes a contact point, it creates an electrical pulse that travels down the spark plug wire to the spark plug, giving it a command to fire. Due to the high voltage inside the distributor, these caps and rotors are very susceptible to wearing out or having to be replaced.
How to Put the Spark Plug Wires in the Right Firing Order
Putting the spark plug wires in the correct order is relatively easy, but it requires some concentration.
If just replacing spark plugs, change the plugs one chamber at a time. Simply disconnect the wire from each chamber, remove the plug, insert the new plug and reconnect the loose spark plug wire. This exact procedure is also the best way should you need to replace the sparkplug wire as well as the plug. Replacing the wire from the cap to the plug one at a time will prevent any confusion or miswiring.
What Happens If I put the Wires on Wrong?
If the wrong cylinder wire is connected to the wrong plug and an attempt to start the car is made, the engine will misfire and idle roughly. If more than two wires are disconnected, the car will simply not start.
Often the spark plug wires are numbered, and that identification can be used to help arrange the wires from the correct connection on the cap to the correct plug. Trace each wire from the plug to the appropriate connection on the distributor cap.
What is the History of the 302 Small Block?
The Ford 302 was a V8 engine that Ford used as its primary powerplant for thirty-three years. Nicknamed the Windsor for the location it was built (Windsor, Ontario), the engine was the successor to the Ford - Y block engine used during most of the 50s.
The engine found its way into various automobiles, including the Mustang, Mercury Cougar, Ford Explorer, LTD, and even the Ford F150. Over the years, the engine also found its way into various boat applications. While it started as a 221 cu in (3.6L) in 1962, the engine evolved into the 351 cu in (5.8L - dubbed the Cleveland) for a couple of years, but the most common version was the 302 cu. It (5.0 L non-HO was Ford's primary motor from 1968 to 2001. At its peak in the late sixties and seventies, Ford promoted their engine as producing 290 hp @ 5800 rpm, which more than proved to be a match for the popular Chevy Camaro Z28. Eventually, Ford phased out the small v-shaped block in favor of a more modular V8.
Are 302 Engines Still available?
Car enthusiasts constantly working on restoring these classic vehicles know that the demand for a 302 ci crate engine remains high. Ford Performance Parts has the engine available for around $10,000, while other purveyors have them listed for less money. This allows a restorer to select and pay for the warranty they wish to place on the engine. There are many other purveyors who produce specific crated 302 engines designed for specific models. (Note - a customer needs to be careful about selecting the correct 302 for their particular vehicle).
