What is the spark plug gap on a 1966 Chevy truck?
The typical spark plug gap for most 1966 Chevy trucks is 0.035 inches (0.89 mm) when using stock ignition equipment, but the exact gap can vary based on engine type and any aftermarket upgrades.
Engine options in 1966 Chevy trucks
Chevrolet offered inline-six and small-block V8 powertrains in 1966 pickups. While the standard gap generally remains around a common value for stock setups, it’s important to note the exact specification can vary slightly by engine and ignition configuration.
Common gap for stock ignition
For the typical stock ignition used in 1966-era engines, the recommended spark plug gap is 0.035 inches (0.89 mm) for the following engines:
- Inline-six engines (such as the 230/250 family) — gap: 0.035 inches
- Small-block V8 engines (283/327) — gap: 0.035 inches
Note: If your truck has an aftermarket electronic ignition or a modern spark plug with a different concours recommendation, consult the plug manufacturer’s specification and adjust accordingly. Some setups may use gaps as large as 0.040–0.045 inches, but that is not typical for stock 1966 engines.
How to measure and set the spark plug gap
These steps help you check and adjust the gap on a 1966 Chevy truck, ensuring you match the engine’s specification.
- Identify the engine type (I6 or V8) and confirm the spark plug type and thread size.
- Remove the spark plug and inspect the electrode for wear; replace if worn beyond spec.
- Use a spark plug gauge to measure the gap between the center and ground electrodes.
- If the gap is too small, gently bend the ground electrode to widen the gap in small increments; if too wide, reposition until the target gap is reached. Do not force the bend.
- Reinstall plugs and torque to the manufacturer’s specification for your engine (verify in the service manual).
- Reconnect ignition wires and start the engine to check for smooth operation and absence of misfires.
Always gap plugs to the exact specification for your engine and plug type. Incorrect gaps can cause misfires, rough idle, or poor performance.
Additional considerations
Beyond the stock spec, consider these factors when selecting plugs and setting gaps for a 1966 Chevy truck.
- Plug type and heat range: Use the recommended heat range for your engine and driving conditions.
- Ignition system type: If the truck has been converted from points to electronic ignition, confirm the plug gap recommended for the new system.
- Altitude and climate: In extreme conditions, a slight adjustment may be advised by a trusted source; otherwise, stick to the standard spec.
Bottom line: for most 1966 Chevy trucks with stock ignition, a 0.035-inch gap is the standard starting point. Verify with the specific engine manual or spark plug manufacturer if you have non-stock components.
Summary
In short, the conventional spark plug gap for a 1966 Chevy truck’s stock ignition is 0.035 inches (0.89 mm) across typical inline-six and small-block V8 engines. Always confirm with the exact engine variant and any aftermarket changes, and follow proper procedures for checking and adjusting gaps to maintain optimal engine performance.
What is the spark plug gap on a 302 motor?
You are fine at 0.035. The Spark Plug to use is the one recommended by your cylinder head manufacturer. The Spark Gap is then the Gap recommended by the Spark Plug Manufacturer for that particular Spark Plug. It's that simple but if you want to get fancy, read on.
What is the correct spark plug gap for a Chevy 350?
The Chevy 350 spark plug gap is 0.035 inches.
Make sure the spark plugs are clean and free of dirt and other debris.
What is the spark plug gap on a 1966 Chevy 327?
For a 327 engine, set the spark plug gap precisely between 0.035 and 0.045 inches. Use a feeler gauge to measure and adjust the gap carefully without damaging the electrode. Incorrect gaps cause weak sparks, resulting in misfires or rough idling.
What is the spark plug gap on a 289 engine?
The 289: Since you are still using a stock coil and have essentially switched to electronic ignition for firing that coil (point elimination), I recommend maintaining the factory-recommended plug gap of . 032-. 036.
