12 Volt Bosch Black Coil, 3.4 Ohm

OVERVIEW

When it comes to the heart of your air-cooled Volkswagen''s ignition system, nothing carries the weight of history and reliability quite like a genuine Bosch component. This 12-Volt Bosch Black Coil is the industry standard for enthusiasts who demand a consistent, high-energy spark without the headache of modern, low-quality imitations. Engineered to provide a robust 3.4 Ohm primary resistance, this coil is the perfect bridge between vintage reliability and modern performance. Whether you are cruising the coastline in a weekend Type 1 or pushing a heavy Type 2 Transporter through mountain passes, this oil-filled canister ensures that your ignition system remains cool and efficient, preventing the dreaded heat-soak that often plagues lesser-quality coils. It is designed to withstand the unique environmental challenges of the VW engine bay, providing the voltage necessary to jump the gap even under high-load conditions.

The versatility of the Bosch Black Coil makes it an essential upgrade or replacement for a wide array of engine configurations. It is perfectly suited for standard points-and-condenser setups, where its internal resistance protects your points from premature burning, yet it is also powerful enough to drive 4-cylinder and 6-cylinder electronic ignition modules like the Pertronix Ignitor series. By delivering a steady 7.4 Ohm secondary resistance, it ensures that every cylinder fires with precision, improving throttle response, idling stability, and overall fuel economy. This isn''t just a replacement part; it is an investment in your Volkswagen''s longevity. At Appletree Automotive, we know that a weak spark is the enemy of performance, and this genuine Bosch unit is the solution for owners who want to "set it and forget it" with their ignition timing and spark delivery.

FITMENT

This 12-volt ignition coil is designed for a wide range of air-cooled and water-cooled vintage applications. While it is a direct fit for 12-volt systems, it is also the premier choice for owners performing 6-volt to 12-volt conversions.

• Volkswagen Type 1: Beetle and Bug (1967-1979)
• Volkswagen Super Beetle: (1971-1979)
• Volkswagen Type 2: Bus, Transporter, Station Wagon, and Kombi (1967-1979)
• Volkswagen Type 3: Fastback, Squareback, and Notchback (1967-1973)
• Volkswagen Type 181: The Thing (1973-1974)
• Volkswagen Karmann Ghia: (1967-1974)
• Custom Applications: Ideal for Sandrails, Dune Buggies, and Trikes utilizing VW-based engines.
• Multi-Cylinder Engines: Compatible with various 4-cylinder and 6-cylinder electronic ignition conversions.

SPECS

Precision engineering meets rugged construction in this genuine Bosch unit. Below are the technical specifications for the 00-9575-0 model:

• Primary Resistance: 3.4 Ohms
• Secondary Resistance: 7.4 Ohms
• Voltage Compatibility: 12-Volt Systems Only
• Internal Construction: Oil-Filled for maximum heat dissipation
• Canister Diameter: 2 3/16 inches (Standard 56mm)
• Canister Height: 4.573 inches
• Overall Height: 5.68 inches
• Top Flange Diameter: 2 1/2 inches
• Weight: 1.6 lbs
• OE Part Number: 9 244 771 008
• Finish: Classic Bosch Black with standard terminal markings

PRO TIPS

Tip 1: Proper Mounting Orientation

While many enthusiasts mount their coils in various positions for aesthetic reasons, the Bosch Black Coil is an oil-filled design. For maximum longevity and heat management, it is highly recommended to mount the coil vertically with the terminals facing upward. This ensures that the internal windings remain fully submerged in the cooling oil, preventing "hot spots" that can lead to internal short-circuiting over time. If you must mount it horizontally, ensure it is securely clamped to a metal surface that can act as a heat sink to help pull temperature away from the canister.

Tip 2: Understanding Terminal Markings

Don''t let the simplicity of the wiring fool you; getting it backward can damage your ignition components. On this Bosch coil, Terminal 15 is your positive (+) feed, which should be connected to your ignition switch (the "on" position). Terminal 1 is the negative (-) side, which connects to your distributor (points or electronic module). If you are using an electronic ignition like a Pertronix, double-check their specific wiring diagram, as they often require the red wire to go to Terminal 15 and the black wire to Terminal 1. Always ensure your connections are tight and free of corrosion to maintain the full 3.4 Ohm resistance profile.

Tip 3: Matching Coil Resistance to Ignition Type

One of the most common mistakes in the VW world is using a "Blue Coil" or a high-output performance coil with a system that isn''t designed for it. The 3.4 Ohm primary resistance of this Black Coil is specifically optimized for street-driven Volkswagens. This resistance level is high enough to prevent your points from arcing and burning out prematurely, while still being low enough to provide a powerful spark for electronic ignitions. If you find your car is "eating" points every 1,000 miles, check your coil resistance; switching back to this genuine Bosch Black Coil often solves the problem by restoring the correct electrical balance to the circuit.