Spark Plug Gap for a 3.7L V6: What Drivers Need to Know

For most modern 3.7L V6 engines from major manufacturers (Ford, Jeep/Dodge/Chrysler), the typical spark plug gap specification falls between 0.040 and 0.050 inches (1.0–1.3 mm), with many factory specs clustering around 0.040–0.044 inches. However, the exact gap is engine- and model-specific, so the only reliable answer for your vehicle is in the owner’s manual or the under-hood emissions/engine label.

Why “3.7 V6” Isn’t Enough to Give One Exact Gap

The phrase “3.7 V6” describes the engine displacement and cylinder layout, but not the manufacturer, model year, or specific engine family. Ford’s 3.7L Duratec V6, Chrysler/Jeep’s 3.7L PowerTech V6, and Nissan’s various 3.5/3.7 V6 families, for example, all have different ignition designs and potentially different spark plug recommendations—even when the displacement figure looks similar.

Typical Spark Plug Gap Ranges by Common 3.7L V6 Applications

The following examples outline common spark plug gap ranges for popular 3.7L V6 engines sold in North America. These ranges are based on manufacturer service information and plug makers’ catalogs, but final confirmation should always come from your specific vehicle documentation.

Ford 3.7L Duratec V6 (e.g., Mustang, F-150, Edge, Explorer)

Ford’s 3.7L Duratec V6 appeared in several models in the 2010s, often with coil-on-plug ignition and long-life iridium or platinum plugs. These engines typically use a relatively tight plug gap to ensure reliable ignition under varying load and boost conditions (if adapted for fleet or performance uses).

Typical spark plug gap range for Ford 3.7L Duratec V6:

• Common spec: around 0.040–0.044 in (1.0–1.1 mm)
• Example applications: 2011–2014 Mustang V6, 2011–2014 F-150 3.7L, some Edge/Explorer 3.7L trims
• Many OEM Motorcraft plugs come pre-gapped very close to spec and require only verification, not major adjustment.

In practice, Ford owners should confirm the exact gap on the under-hood sticker or in the owner’s manual, since small differences by model year or calibration can exist.

Jeep/Dodge/Chrysler 3.7L PowerTech V6 (e.g., Liberty, Dakota, Ram, Nitro)

The Chrysler/Jeep 3.7L PowerTech V6, used widely in trucks and SUVs in the 2000s and early 2010s, also has a broadly consistent plug gap range. This engine generally specifies a moderately wide gap tailored to its ignition coil and combustion chamber design.

Typical spark plug gap range for Chrysler/Jeep 3.7L V6:

• Common spec: around 0.040 in (1.0 mm)
• Typical models: Jeep Liberty 3.7L, Dodge Dakota 3.7L, Dodge Ram 1500 3.7L, Dodge Nitro 3.7L
• Some service bulletins and plug makers list a range of about 0.040–0.043 in, but 0.040 in is the usual reference value.

Drivers of these vehicles should still confirm with their specific model-year data, as Chrysler occasionally revised ignition-related specs.

How to Find the Exact Spark Plug Gap for Your 3.7L V6

Because the 3.7L V6 description covers multiple unrelated engine families, the precise spark plug gap must come from official documentation for the exact vehicle. Several key sources provide this information clearly and reliably.

The following are the most reliable places to find the correct spark plug gap for your specific vehicle:

1. Owner’s manual: Often lists spark plug type and gap in the maintenance or specifications section.
2. Under-hood emissions/engine label: A decal under the hood sometimes includes spark plug gap along with tune-up data.
3. Service manual (factory or dealer-level): Contains full ignition specifications, including correct plug part number and gap.
4. Reputable parts catalogs: Websites for NGK, Denso, Motorcraft, AC Delco, and major auto parts chains often list the factory gap alongside the recommended plug.
5. Dealership service department: Providing your VIN to a dealer can yield the exact gap specification in their service database.

Cross-checking at least two of these sources is a smart way to ensure the gap you set matches the automaker’s latest official recommendation.

Why Spark Plug Gap Matters

The spark plug gap directly influences how easily the spark jumps the electrodes and ignites the air-fuel mixture. Even a small deviation from the recommended size can change how the engine behaves, especially under heavy load or at high RPM.

Effects of an Incorrect Spark Plug Gap

Setting the gap properly is not just about following a number—it has practical consequences for performance, fuel economy, and reliability.

The main effects of an incorrectly set spark plug gap include:

• Too wide a gap: Can cause misfires under load, hard starting, rough idle, and possible check-engine lights, especially as coils and wires age.
• Too narrow a gap: Can lead to incomplete combustion, reduced power, higher emissions, and fouling over time.
• Coil stress: A significantly wide gap forces ignition coils to work harder, potentially reducing their lifespan.
• Fuel economy impact: Both overly tight and overly wide gaps can reduce fuel efficiency and increase emissions.

Maintaining the factory-specified gap helps keep the ignition system operating in the range it was designed for, supporting optimal performance and durability.

Checking and Setting the Spark Plug Gap

Even when plugs are sold as “pre-gapped,” experienced technicians verify the measurement before installation, especially for critical engines or performance applications. Small variations from shipping or handling can alter the gap.

The basic steps to check and set spark plug gap are as follows:

1. Use the correct tool: A wire-style or blade-style feeler gauge sized in inches and millimeters works best.
2. Measure the existing gap: Insert the correct gauge between the center and ground electrode to see if it fits snugly without forcing.
3. Adjust carefully if needed: Gently bend only the ground electrode, never the center electrode or porcelain, to open or close the gap.
4. Avoid levering on fine-wire tips: Iridium and some platinum plugs have delicate center electrodes—use a plug gapping tool designed for fine-wire plugs.
5. Re-check the measurement: After each small adjustment, re-measure until it matches the factory specification.

By taking a minute to verify and adjust the gap, you reduce the risk of misfires or drivability complaints that could otherwise appear right after a plug change.

Putting It All Together

For most 3.7L V6 engines from Ford and Chrysler/Jeep, a spark plug gap in the neighborhood of 0.040–0.044 inches (about 1.0–1.1 mm) is typical, with many factory specs centering on 0.040 in. However, because “3.7 V6” refers to several different engine designs across multiple brands and years, there is no single universal gap value that fits every case.

Summary

The spark plug gap for a 3.7L V6 engine generally falls between 0.040 and 0.050 inches, with many Ford and Chrysler/Jeep applications specifying around 0.040–0.044 inches. To be certain, you must check the owner’s manual, the under-hood label, or a trusted service/parts database for your exact year, make, model, and engine code. Once you have the correct specification, verify and, if needed, carefully adjust each plug to that value before installation to ensure reliable ignition and optimal engine performance.

What is the firing order of a 3.7 L Ford?

The firing order for the Ford 3.7L V6 engine is 1-4-2-5-3-6. This sequence applies to many Ford and Lincoln models that use this engine, such as the Explorer, F-150, and Taurus. 
This video explains the firing order and cylinder numbering for the Ford 3.7L V6 engine: 58sWirelesSHackYouTube · Jun 30, 2024

• Firing Order: 1-4-2-5-3-6 
• Cylinder Identification:
  • When viewed from the front of the vehicle, cylinders 1, 2, and 3 are typically in the rear bank (back of the engine) and cylinders 4, 5, and 6 are in the front bank. 
  • For engines mounted in a front-wheel-drive vehicle, cylinder 1 is the one closest to the firewall, and cylinder 4 is the one closest to the radiator. 
  • In a rear-wheel-drive or truck application, the engine is rotated 90 degrees, so the cylinder layout will differ, but the cylinder numbering and firing order remain the same. 

What is the spark plug Gap on a 3.7 L V6 Jeep?

Denso Set of 6 U-Groove Design Spark Plugs Gap 0.044 For Dodge Jeep 3.7L V6.

What is the torque on a spark plug on a 2006 Jeep Liberty 3.7 V6?

Engine

	Socket Size	Torque Spec
Spark Plugs	5/8″ Spark Plug Socket	20 ft-lbs
Tensioner Pulley	15mm	30 ft-lbs
Thermostat Housing Bolts	8mm	9 ft-lbs
Water Pump Bolts	13mm	40 ft-lbs (Tighten in Star Pattern to 20 ft-lbs, then 30, then 40)

What is the spark plug Gap on a 2005 Dodge Ram 1500 3.7 V6?

Notes: Gap 0.044″.