What is the spark plug gap on a 5.7 350 Silverado?
The typical spark plug gap for most 5.7L Silverado engines is 0.060 inches (1.52 mm). However, exact gap can vary by year, plug type, and specific GM specification, so always verify the correct value for your vehicle and plug brand.
The 5.7L V8 used in Silverado pickups—commonly referred to as the 350—relies on a precise spark plug gap to balance ignition, fuel efficiency, and emissions. While 0.060 inches is a widely cited standard, different plug designs or service bulletins can call for a slightly different gap. This article breaks down the typical gap, when variations occur, and how to measure and set the gap correctly.
Typical spark plug gap for the 5.7L Vortec in Silverado
Before listing common values, note that the factory recommendation is most often 0.060 inches (1.52 mm) for many OEM and aftermarket plugs used in the 5.7L Vortec. Some plug types or specific model years may call for a narrower gap; always check the plug manufacturer’s spec and your GM service manual for the exact figure.
- 0.060 in (1.52 mm) – common baseline for many OEM and aftermarket plugs on the 5.7L Vortec.
- 0.040–0.052 in (1.0–1.3 mm) – may be specified for certain plug designs or performance-focused applications; verify with the plug manufacturer.
- Always confirm the exact gap for your particular plug part number and year, as deviations can affect ignition and warranty coverage.
Concluding note: For most Silverado 5.7L engines, target 0.060 inches, but always confirm the exact specification for your chosen spark plug and vehicle year.
How to check and set the spark plug gap
Before you start, understand that you should measure the gap on a used or new spark plug with the same part number you plan to install, and then adjust if needed to the required specification.
- Identify the correct gap specification for your plug type and year, typically 0.060 inches (1.52 mm) for many 5.7L Silverado applications.
- Use a precise feeler gauge to measure the current gap. Insert the appropriate blade until it just fits with a slight drag.
- If the gap is too wide, gently bend the ground electrode toward the center electrode in small increments until the gauge fits with the correct tolerance. If the gap is too narrow, gently widen the gap using the same method or replace the plug with one that matches the required gap.
- Recheck the gap after any adjustment to ensure it is exact. Do not guess or force a larger gap.
- Install and torque the plug to the manufacturer’s specification, then recheck overall engine operation during testing.
Concluding: Proper gap setting is essential for reliable ignition and optimal engine performance. Always use the correct plug and verify the gap with a gauge before installation.
Year-by-year or plug-type considerations
Because plug gaps can vary by year, emissions standards, and plug design, always consult the specific spark plug packaging or GM service information for your Silverado’s year. If you switch to an aftermarket plug with a different recommended gap, adjust accordingly and test for smooth operation.
Summary
For most 5.7L Silverado models, the standard spark plug gap is 0.060 inches (1.52 mm). Always confirm the exact gap for your vehicle’s year and plug part number, and measure carefully with a proper feeler gauge. When in doubt, consult the owner's manual or GM service information, and replace plugs with ones specified for your engine to maintain performance and reliability.
