What is the spark plug gap on a 57 Chevy?
Typically 0.035 inches (0.89 mm) for most 1957 Chevrolets, especially the 283 V8. The exact gap can vary by engine and spark plug type; always consult the spark plug manufacturer's specification or the factory service manual for your exact model.
Context and typical ranges
The spark plug gap on vintage Chevrolets is tied to ignition timing, starting performance, and the plug design. In 1957, most Chevrolets used a 12-volt ignition with relatively similar gap targets, commonly around the mid-0.03 inch range.
Below are the common spark plug gap values for the era's main Chevrolet configurations, to serve as a quick reference when restoring a 1957 model.
- 283 cubic inch V8: typically 0.035 inches (0.89 mm).
- Six-cylinder 235/236 cubic inches: commonly 0.030–0.035 inches (0.76–0.89 mm) depending on the plug and tune.
Note: These figures are general guidelines. Always verify the exact gap with the spark plug manufacturer and the specific vehicle's service manual, especially if you are using modern plug designs.
How to check and set the gap
Here are the steps to ensure the correct spark plug gap when installing or re-gapping plugs for a 1957 Chevy.
- Identify the exact gap spec for your engine and plug from the plug packaging or the service manual.
- Use a precise feeler gauge to measure the current gap.
- If adjustment is needed, gently bend the side electrode or use the recommended gap tool to reach the target gap.
- Re-measure, then torque the plug to the proper specification during installation.
Correct gaps help ensure smooth starting, better fuel economy, and reduced misfires in classic carbureted setups.
Other considerations for 1957 Chevrolets
Gap size is only one factor. Heat range, electrode design, and ignition system condition also influence performance. When swapping to modern plugs, verify the manufacturer's recommended gap and heat range for your engine.
Practical notes for plug selection
If you choose modern replacements, you may start at the historically common 0.035" gap, and adjust slightly based on cold starts and acceleration feel, always keeping within the plug maker's recommended range.
Summary
For most 1957 Chevys with the 283 V8, a spark plug gap of 0.035 inches (0.89 mm) is typical. Confirm this value for your exact engine and plug, and adjust as needed per the plug manufacturer and service manual.
