Do you love working on your Chevy 350? If you handle your own maintenance and repairs, you need to know the firing order for Chevy 350 engines. Getting the Chevy 350 firing order wrong can mean the difference between a running truck and one that won’t start.
In this article, I share the Chevy 350 firing order and break down the basics of this popular engine. I also explain why the firing order matters so much and point out how it differs from other engines. At the end of the guide, I answer some of your top questions about various Chevy firing orders.
What Is the Firing Order of a Chevy 350?
The Chevy 350 fires in the order 1-8-4-3-6-5-7-2. Most old-school Chevy engines use this same firing order. This sequence tells you which spark plugs and wires fire, and in what order, if your engine uses a distributor. For the spark plugs to fire at the right time, you must wire the Chevy 350 this way.
To set up this firing order, find when the piston reaches top dead center on the compression stroke. Make sure the rotor inside the distributor points to the correct spark plug terminal so the firing order works. On the Chevy 350, you begin with spark plug #1, which sits at the first position in the distributor cap.
Some small-block engines use a High Energy Ignition (HEI) distributor. In this setup, electricity flows from the ignition coil straight to the spark plug, moving clockwise around the cap.
There is one exception to this firing order on the Chevy 350. LS engines can also be 350s, but they fire in the order 1-8-7-2-6-5-4-3. If you are not sure how your Chevy engine is wired, check the information in your service manual. Even if you feel confident, it never hurts to double-check.
What is a Chevy 350 Engine?
Chevy 350 engines measure 350 cubic inches, which equals 5.7 liters. Every one of these engines is a small-block V8 with a 4.00-inch bore and a 3.48-inch stroke. Horsepower runs from 145 up to more than 370, depending on the make, model, and year of the vehicle. It can also deliver up to 380 lb-ft of torque, so it works well for towing. Fuel mileage is not a strong point for this V8 engine.
The 350 small block engine first appeared in the 1967 Camaro as the L-48 high-performance motor. Just one year later, Chevrolet put it in the Nova. By 1969, the whole Chevy lineup offered a 350.
GM uses RPO (Regular Production Option) codes to identify the engines. You can find the 350 code stamped on the cylinder head, usually on the passenger side of the vehicle. The alternator might hide it, so you may need to look a bit harder. Most of the engine codes start with an L, like the L31 or L46, but some use other letters, such as the ZQ3.
What is a Chevy 350 Firing Order?
The firing order shows the sequence of when the spark plugs fire. The engine can’t run right without it. If you get the firing order correct, the engine runs exactly like it should. If not, the ride can feel rough, or the engine might not run at all.
With the 1-8-4-3-6-5-7-2 firing order, the first spark plug to fire is #1. Then #8, #4, #3, #6, #5, #7, and #2 follow in that order. This ignition order puts the spark where it’s needed.
As combustion pressure pushes the pistons down, the transmission gears and crankshaft move in time. This movement creates the forward or backward motion you need to go somewhere.
What Makes the Firing Order Important?
You might think it doesn’t matter how a car’s spark plugs fire, but they have to fire in the right order. If they don’t, you can run into real problems. The sequence of the cylinders matters for fuel economy, performance, and even the engine’s emissions.
If the cylinders don’t fire in the correct order, unburned fuel will escape from the engine. Depending on how bad the issue is, the wrong fuel and air mix can even stop the engine from starting. At the very least, you’ll notice serious performance problems.
Small Vs. Big Block Chevy Firing Order
Most small and big block Chevy engines use the same firing order. For both, the most common firing order is 1-8-4-3-6-5-7-2.
The small block engines that follow this firing order include these models:
- Chevy 265
- Chevy 283
- Chevy 302
- Chevy 327
- Chevy 350
- Chevy 400
You can also find this firing order in big block engines. Some of these include:
- Chevy 396
- Chevy 406
- Chevy 427
- Chevy 454
With both these small- and big-block engines, you get a strong V8. All of these motors are built to deliver maximum power for a fun ride.
The newer small-block engines are different. These are called LS engines. With the 350, your firing order will be 1-8-7-2-6-5-4-3.
So, what is the difference between the small and big-block Chevy? Size is the main difference. Big-block Chevy motors are larger than the small-block. They also weigh more, but they can create more power.
Other Chevy Firing Orders
- 327. Chevy put the 327 in cars from 1962 to 1969. In the last year, it became the standard V8 in all full-size models. This helped cut costs compared to the 307 V8 found in the Camaro, Nova, and Chevelle. The 327 small block Chevy engine uses the same firing order as the 350. If you need to set the firing order, the Chevy 327 firing order is 1-8-4-3-6-5-7-2.
- 454. Chevy introduced the 454 in 1970 as a 7.4-liter engine. It first appeared in the Corvette LS-5 and made 390 horsepower. Later, Chevy released a 465-horsepower model. The 454 big block Chevy engine uses the same firing order as the small block 350. Set it for 1-8-4-3-6-5-7-2.
- 5.3-Liter. The 5.3-liter Chevy engine is a newer model. Because of this, it uses a different firing order from the 350. In the 5.3-liter 350 engines, the firing order is 1-8-7-2-6-5-4-3. Odd cylinders sit on the driver’s side of the car, while even cylinders sit on the passenger’s side.
- With an HEI Distributor Cap. The High Energy Ignition (HEI) distributor cap is newer technology. This distributor sends voltage from the ignition coil to the plug. Even with the HEI distributor cap, the firing order stays the same as the 350 small blocks. It is 1-8-4-3-6-5-7-2.
What If the Firing Order of a Chevy 350 is Wrong?
If you mix up the spark plug wires on an older engine with a distributor, the engine can misfire, run rough, or not start at all. If you just swapped plugs or wires and now see performance problems, you probably set the firing order wrong. You can avoid this headache by replacing one plug and its wire at a time.
How Do I Fix the Wrong Chevy 350 Firing Order?
If you set the firing order of a Chevy 350 wrong, you must fix it before the truck or car will drive right. Turn the crankshaft by hand until the timing mark lines up with the Top Dead Center (TDC) mark on the timing cover.
Pull off the distributor cap and note where the rotor points. It must face the number one terminal on the cap. If it does not, turn the crankshaft again until the rotor reaches the number one position. Follow each wire and make sure it connects to the correct spark plug.
Where is the Number 1 on a Chevy 350 Distributor Cap?
On your Chevy 350 motor, the cylinder numbers start at the front of the engine, beginning on the driver’s side. The second cylinder sits toward the front on the passenger’s side. The numbers move from left to right and switch sides as they go. If you get stuck, use a Chevy 350 firing order diagram.
Where Can I Find a Chevy 350 Firing Order Diagram?
To help you find the right firing order for your Chevy 350, I included a diagram. You can also find this info in other places. Check your Chevy service manual or do a quick search online to pull up the correct firing order.
Newer cars with a coil-over-plug design save you from worrying about firing orders. Still, if you love your Chevy 350 and do not mind working on it, knowing the correct firing order will save you a lot of trouble. Most Chevy 350 firing orders run 1-8-4-3-6-5-7-2, though a few can differ.
For that reason, you should check the info in your Chevy’s service manual. Using the wrong firing order can cause big problems, so you do not want to make mistakes.
Make sure your engine runs the way it should by hooking up the distributor with the right Chevy 350 firing order the first time. If you need more help, talk to your local auto repair shop.