What is the spark plug gap on a 5.7 liter engine?
The typical spark plug gap for the common GM 5.7L Vortec (5700) V8 is 0.060 inches (1.52 mm). If your 5.7L engine is from a different brand or generation, the gap may differ, so always verify the exact specification for your engine and plug type.
This article explains the commonly used gap values, notes brand-specific differences (such as GM versus Chrysler variants), and provides practical guidance on how to measure and set the gap safely. It also clarifies why the gap can vary and what to check before installing new plugs.
Typical gap expectations for the GM 5.7L Vortec
Before listing exact numbers, it’s important to understand that the 5.7L Vortec in many GM trucks and SUVs uses a standard gap around 0.060 inches. The precise figure can depend on plug type (copper, platinum, or iridium) and whether the plug arrives pre-gapped by the manufacturer. Always confirm with the plug packaging or the vehicle’s service manual.
Common plug types used with 5.7L GM engines include copper-core, platinum, and iridium. The following references reflect typical maintenance practices, but exact specs may vary by plug model.
- Copper-core plugs: 0.060 inches (1.52 mm)
- Platinum or iridium plugs: often 0.060 inches (1.52 mm); verify if the plug is pre-gapped differently
Concluding: In practice, measure the gap with a gauge and adjust to the exact spec in your manual or on the plug packaging, as some aftermarket plugs may come pre-gapped differently.
Other 5.7-liter variants and their gaps
Beyond GM’s 5.7L Vortec, other 5.7 engines (notably Chrysler’s Hemi) use different recommended gaps. The Hemi 5.7 commonly uses around 0.040 inches (1.0 mm), but always verify with the vehicle’s manual and the plug manufacturer’s guidance. Mismatched gaps can affect ignition performance and driveability.
- Chrysler 5.7 Hemi: typically 0.040 inches (1.0 mm)
- Other 5.7 variants: gaps vary; check OEM guidance for the exact engine
Concluding: Since the term “5.7-liter” spans multiple brands and generations, identify the exact engine family and year, then confirm the recommended plug gap from the official spec.
How to check and set the spark plug gap
Proper tools and careful technique are essential. Gather a spark plug gap gauge, the correct replacement plugs, and a torque wrench. Follow these steps:
- Identify the exact engine and obtain the OEM plug gap specification from the manual or packaging.
- Carefully remove the spark plug to avoid damaging threads in the cylinder head.
- Measure the gap with the gauge; if out of spec, adjust the gap by gently bending the ground electrode (or replace the plug if needed). Take care not to damage the center electrode.
- Thread the plug in and tighten to the manufacturer’s torque specification for your engine and plug type.
- Repeat for all cylinders, then start the engine and check for proper ignition performance.
Concluding: Recheck gaps after adjusting, and follow OEM torque specs. If you’re unsure, consult a professional mechanic.
Summary
For the common GM 5.7L Vortec 5700, the typical spark plug gap is 0.060 inches (1.52 mm). Other 5.7-liter engines, such as Chrysler’s Hemi, may use a different gap (often around 0.040 inches). Since “5.7-liter” covers multiple brands and generations, always verify the exact gap with the OEM documentation or plug packaging before installation. Regularly confirm gaps during maintenance to ensure optimal ignition performance and avoid misfires.
