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Autolite 425 Spark Plug
| Brand | Autolite 425 |
|---|---|
| Resistance | 5000 |
| Ground Electrode Tip Design | Tapered |
| Ground Electrode Core Material | Nickel |
| Electrical Terminal Type | Stud |
| Center Electrode Core Material | Copper |
| Center Electrode Tip Material | Nickel |
| Pre-Gap Size | 0.030 |
| Pre-Gap Size | 0.80 |
| Ground Electrode Quantity | 1 |
| Hex Size | 13/16" |
| Hex Size | 21 |
| Seat Type | Flat |
| Reach | 0.500 |
| Reach | 13.0 |
| Thread Diameter | 14.0 |
| Resistor Type | Yes |
| Center Electrode Design | Standard / regular |
| Ground Electrode Tip Material | Nickel |
| Insulator Material | Ceramic |
| Insulator Type | Short |
| Product line | Copper Resistor Spark Plug |
| Fits | Ford and Volkswagen · 38 vehicles |
OE form, fit and function. A direct replacement spark plug for straightforward installation.
Copper core design. Delivers quick starts, smoother acceleration, and better fuel economy.
Ceramic insulator. Built with a nickel-tipped electrode for reliable ignition performance.
Cross-references Autolite 306, OSC 4012 and 44F for the same application. See all 5.
Autolite 425 Copper Resistor Spark Plug
The Autolite 425 is a copper resistor spark plug built for OE-style fit, form, and function in a range of classic Volkswagen Beetle and Ford Escort applications. It is engineered for quick starts, smooth acceleration, and consistent ignition performance at a value-focused price point.
Key Features
- Copper center electrode for dependable ignition response
- 5000 ohm resistor design helps reduce electrical noise
- Nickel center and ground electrode tip materials
- Standard regular center electrode design with a tapered ground electrode tip
- Flat seat, 14 mm thread diameter, 0.500 in. reach
- Pre-gapped at 0.030 in. / 0.80 mm
- Ceramic short insulator with stud terminal type
Product Details
Autolite Copper Resistor Spark Plugs are built as OE-style replacements for foreign and domestic vehicles that call for this specification. Part number 425 uses a copper core center electrode, nickel tip materials, and a resistor configuration to support stable ignition performance and reduced radio-frequency interference. This part cross-references Champion Spark Plug 306 for the same application.
Compatible With classic Volkswagen Beetle and Ford Escort applications, including Fits 1950-1978 Volkswagen Beetle, N/A and Fits 1956-1961 Ford Escort, N/A. The Autolite 425 is also listed for Fits 1979 Volkswagen Beetle, N/A, making it a relevant choice for owners maintaining original-style ignition service on these vehicles.
Common Issues This Part Can Address
- Hard starting caused by worn or fouled spark plugs
- Rough idle from inconsistent spark delivery
- Reduced throttle response during acceleration
- Ignition noise from a non-resistor plug setup
- Maintenance replacement for OE-style tune-up service
Installation Notes and Tips
Verify thread diameter, reach, seat type, and gap before installation. This plug is pre-gapped at 0.030 in. / 0.80 mm, but the gap should still be checked against the vehicle specification before use. Confirm the stud terminal style matches the ignition lead connection and inspect the cylinder head threads for wear or contamination before tightening.
Quality Assurance
Autolite supplies ignition products to the automotive aftermarket and OE manufacturers, and the 425 is built to match OE-style requirements for the listed applications. Part number 425 is a practical replacement for service work on classic Volkswagen Beetle and Ford Escort ignition systems.
| Year | Make | Model | Liters | Cylinders | Position | Notes |
|---|---|---|---|---|---|---|
| 1979 | Volkswagen | Beetle | — | — | N/A | .024"/0.6mm; OE Style; Copper Resistor Spark Plug |
| 1978 | Volkswagen | Beetle | — | — | N/A | Spark plug with a gap of .024 and OE style.; Copper Resistor Spark Plug |
| 1977 | Volkswagen | Beetle | — | — | N/A | Spark plug with a gap of .024 and OE style.; Copper Resistor Spark Plug |
| 1976 | Volkswagen | Beetle | — | — | N/A | Spark plug with a gap of .024 and OE style.; Copper Resistor Spark Plug |
| 1975 | Volkswagen | Beetle | — | — | N/A | Spark plug with a gap of .024 and OE style.; Copper Resistor Spark Plug |
| 1974 | Volkswagen | Beetle | — | — | N/A | Spark plug with a gap of .024 and OE style.; Copper Resistor Spark Plug |
| 1973 | Volkswagen | Beetle | — | — | N/A | Spark plug with a gap of .024 and OE style.; Copper Resistor Spark Plug |
| 1972 | Volkswagen | Beetle | — | — | N/A | Spark plug with a gap of .024 and OE style.; Copper Resistor Spark Plug |
| 1971 | Volkswagen | Beetle | — | — | N/A | Spark plug with a gap of .024 and OE style.; Copper Resistor Spark Plug |
| 1970 | Volkswagen | Beetle | — | — | N/A | Spark plug with a gap of .024 and OE style.; Copper Resistor Spark Plug |
| 1969 | Volkswagen | Beetle | 1.5L | H4 | N/A | Spark plug with a gap of .024 and OE style.; Copper Resistor Spark Plug |
| 1968 | Volkswagen | Beetle | 1.5L | H4 | N/A | Spark plug with a gap of .024 and OE style.; Copper Resistor Spark Plug |
| 1967 | Volkswagen | Beetle | 1.5L | H4 | N/A | Spark plug with a gap of .024 and OE style.; Copper Resistor Spark Plug |
| 1966 | Volkswagen | Beetle | 1.2L | H4 | N/A | Spark plug with a gap of .024 and OE style.; Copper Resistor Spark Plug |
| 1966 | Volkswagen | Beetle | 1.3L | H4 | N/A | Spark plug with a gap of .024 and OE style.; Copper Resistor Spark Plug |
| 1965 | Volkswagen | Beetle | — | — | N/A | Spark plug with a gap of .024 and OE style.; Copper Resistor Spark Plug |
| 1964 | Volkswagen | Beetle | — | — | N/A | Spark plug with a gap of .024 and OE style.; Copper Resistor Spark Plug |
| 1963 | Volkswagen | Beetle | — | — | N/A | Spark plug with a gap of .024 and OE style.; Copper Resistor Spark Plug |
| 1962 | Volkswagen | Beetle | — | — | N/A | Spark plug with a gap of .024 and OE style.; Copper Resistor Spark Plug |
| 1961 | Ford | Escort | — | — | N/A | 1/2" Reach; .025 Gap; OE Style; Copper Resistor Spark Plug |
| 1961 | Volkswagen | Beetle | — | — | N/A | Spark plug with a gap of .024 and OE style.; Copper Resistor Spark Plug |
| 1960 | Ford | Escort | — | — | N/A | 1/2" Reach; .025 Gap; OE Style; Copper Resistor Spark Plug |
| 1960 | Volkswagen | Beetle | — | — | N/A | Spark plug with a gap of .024 and OE style.; Copper Resistor Spark Plug |
| 1959 | Ford | Escort | — | — | N/A | 1/2" Reach; .025 Gap; OE Style; Copper Resistor Spark Plug |
| 1959 | Volkswagen | Beetle | — | — | N/A | Spark plug with a gap of .024 and OE style.; Copper Resistor Spark Plug |
| 1958 | Ford | Escort | — | — | N/A | 1/2" Reach; .025 Gap; OE Style; Copper Resistor Spark Plug |
| 1958 | Volkswagen | Beetle | — | — | N/A | Spark plug with a gap of .024 and OE style.; Copper Resistor Spark Plug |
| 1957 | Ford | Escort | — | — | N/A | 1/2" Reach; .025 Gap; OE Style; Copper Resistor Spark Plug |
| 1957 | Volkswagen | Beetle | — | — | N/A | Spark plug with a gap of .024 and OE style.; Copper Resistor Spark Plug |
| 1956 | Ford | Escort | — | — | N/A | 1/2" Reach; .025 Gap; OE Style; Copper Resistor Spark Plug |
| 1956 | Volkswagen | Beetle | — | — | N/A | Spark plug with a gap of .024 and OE style.; Copper Resistor Spark Plug |
| 1955 | Volkswagen | Beetle | — | — | N/A | Spark plug with a gap of .024 and OE style.; Copper Resistor Spark Plug |
| 1954 | Volkswagen | Beetle | 1.1L | H4 | N/A | Spark plug with a gap of .024 and OE style.; Copper Resistor Spark Plug |
| 1954 | Volkswagen | Beetle | 1.2L | H4 | N/A | Spark plug with a gap of .024 and OE style.; Copper Resistor Spark Plug |
| 1953 | Volkswagen | Beetle | — | — | N/A | Spark plug with a gap of .024 and OE style.; Copper Resistor Spark Plug |
| 1952 | Volkswagen | Beetle | — | — | N/A | Spark plug with a gap of .024 and OE style.; Copper Resistor Spark Plug |
| 1951 | Volkswagen | Beetle | — | — | N/A | Spark plug with a gap of .024 and OE style.; Copper Resistor Spark Plug |
| 1950 | Volkswagen | Beetle | — | — | N/A | Spark plug with a gap of .024 and OE style.; Copper Resistor Spark Plug |
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