Moroso spark plug indexing washers 14MM flat-seat — precision thin shims for electrode alignment

Moroso 71910 spark plug indexing washers are thin, precision-cut shims designed to rotate and align 14mm flat-seat spark plugs for optimal electrode position and clearance.

These indexing washers let you fine-tune the orientation of the spark plug electrode after the plug is torqued into a 14mm flat-seat cylinder head. Rather than reworking plugs or the head, the washer provides small angular adjustment so the electrode points where you want it. The part is vehicle-specific in fitment and intended for performance tuning, custom engine builds, and restorations where plug electrode positioning matters.

How do these washers affect spark plug orientation?

The Moroso 71910 washers sit between the spark plug and the cylinder head sealing surface, allowing rotational adjustment without altering torque settings. They are precision machined to keep the plug seated correctly while shifting electrode timing orientation by small degrees.

• Fits 14mm flat-seat spark plugs and corresponding cylinder heads.
• Thin, consistent thickness prevents sealing issues when installed properly.
• Enables electrode rotation to face the intake or exhaust side as needed.
• Maintains factory torque specifications when torqued with proper practice.

Will these washers fit my vehicle?

Fitment is vehicle-specific: they are made for 14mm flat-seat spark plug applications only. Confirm your engine uses 14mm flat-seat plugs and verify clearance requirements before purchase to ensure compatibility.

• Designed specifically for 14mm, flat-seat spark plugs.
• Not compatible with tapered-seat or other diameter plugs.
• Check your engine’s plug specification in the service manual or with the parts seller.

How do you install and torque with an indexing washer?

Installation is straightforward: place the washer on the plug’s sealing surface, thread the plug into the head by hand, and torque to the manufacturer’s spec. After torquing, rotate the plug slightly if needed to achieve the desired electrode orientation — the washer will allow the adjustment without losing the proper clamp.

• Hand-start the plug, then use a torque wrench to specified ft·lb or N·m.
• Rotate the mounted plug gently to set electrode angle; avoid over-tightening.
• Use anti-seize or thread lubricant per OEM recommendation to prevent galling.

Are there performance or reliability considerations?

When used correctly, indexing washers provide orientation benefits with minimal compromise to sealing or reliability. Always follow torque specs and use the correct washer thickness for your clearance needs to avoid compression or mis-seating.

• Proper torque and correct washer thickness preserve sealing integrity.
• Not a substitute for damaged seats or worn threads—repair as necessary first.
• Intended for tuning, performance engines, restorations, and custom applications.

Who is this for: The Moroso 71910 14mm flat-seat spark plug indexing washer is aimed at mechanics, engine builders, tuners, and DIY enthusiasts who need precise electrode alignment in 14mm flat-seat plug applications. It's ideal for performance engine tuning, race prep, classic car restorations, and any situation where electrode orientation can improve ignition consistency or clearance. Confirm plug seat type and vehicle compatibility before use, and follow standard torque and installation procedures for safe, reliable results.