Get quick starts and dependable spark with the Autolite Copper Spark Plug 646. It's cataloged for a broad list of vehicles, from the 1987-1988 Buick Skyhawk [L4-2.0L] and 1975-1976 Cadillac DeVille [V8-8.2L] to the 1993-1996 Chrysler Concorde [V6-3.3L] and 1990-2000 Dodge Caravan [V6-3.3L] — see the Buyer's Guide tab for the full application list.
- Copper core center electrode: aids thermal control and improves resistance to fouling.
- High nickel alloy electrodes: the specially engineered center and ground electrode are built for extended life.
- High alumina multi-rib ceramic insulator: provides thermal conductivity and strong insulation.
- Nickel-plated shell: corrosion resistant for added durability.
This is a resistor plug (4,000-ohm resistance) with a standard center-electrode design and mid projection. It uses a 14 mm thread (M14 - 1.25, metric), a 13/16 in hex, a flat seat with the washer included, a 0.75 in (19 mm) reach, and manufacturer heat range 8. It arrives pre-gapped at 0.05 in (1.3 mm) — verify against the vehicle service information before installing. Quantity needed varies by engine (4, 6, or 8); plugs are sold individually, so order the number your engine requires. Country of origin: Mexico. Backed by a 2-year limited warranty.
Interchange: 117 · 41-618 · 41618 · R44XLS6 · R45NSX · R45XLS6 · C95R6 · 7522 · 7922 · W10EC · WR10LCV · WR10LCV+ · 31 · RN14MC5 · RN16YC5 · 4686083 · 3015 · 32721 · 25312033 · 5613932 · 5613946 · 5614128 · SP0RN14MC5 · AGR52-6 · AGR526 · AGS52C6 · AGS52C-6 · SP451 · 4012 · BP5ES-13 · BP5ES13 · GR45 · GR55 · SF6F6 · Manufacturer part number 646
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Frequently Asked Questions
What type of spark plug is the Autolite 646?
It's an Autolite copper spark plug with a copper core center electrode, high nickel alloy electrodes, and a high alumina multi-rib ceramic insulator.
Is the Autolite 646 a resistor spark plug?
Yes. It's a resistor-type plug with 4,000-ohm resistance, which helps suppress ignition-system electrical noise.
What are the thread and fitment specs?
It has a 14 mm thread (M14 - 1.25, metric), a flat seat with the washer included, a 13/16 in hex, and a 0.75 in (19 mm) reach with heat range 8.
Does it come pre-gapped?
It ships pre-gapped at 0.05 in (1.3 mm). Always confirm the correct gap against the vehicle service information before installing.
How many plugs do I need to order?
Quantity varies by engine — the listed applications use 4, 6, or 8. Plugs are sold individually, so order the number your engine requires.
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