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Marine & Outboard Spark Plugs

NGK Surface Gap Spark Plug BUZ8H (7447)

SKU: GB-BUZ8H

$35.00
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The NGK BUZ8H (Stock No. 7447) is a premium resistor-type surface-gap spark plug designed for selected high-performance 2-stroke marine engines. Featuring a nickel centre electrode, copper core and special inductive resistor, it provides reliable ignition while helping suppress electrical interference. BUZ8H is particularly suited to selected Mercury, Mariner, Johnson and Evinrude outboards requiring a short-reach surface-gap plug.

Key benefits

Key Benefits

  • - Surface-gap marine spark plug
  • - Designed for selected high-performance 2-stroke outboards
  • - Special inductive resistor construction
  • - Helps suppress radio and electronic interference
  • - Copper core assists heat dissipation
  • - Nickel centre electrode
  • - Excellent resistance to fouling
  • - No conventional projecting ground electrode
  • - No conventional manual gap adjustment
  • - Short 12.7 mm thread reach
  • - NGK heat range 8

Specifications & Dimensions

  • - Brand: NGK
  • - Part Number: BUZ8H
  • - NGK Stock Number: 7447
  • - Spark Plug Type: Surface-gap / surface-discharge
  • - Thread Diameter: 14 mm / 0.551"
  • - Thread Size: M14 × 1.25
  • - Thread Pitch: 1.25 mm / 0.049"
  • - Thread Reach: 12.7 mm / 0.500"
  • - Hex / Spanner Size: 20.8 mm / 13/16"
  • - NGK Heat Range: 8
  • - Seat Type: Flat / gasket seat
  • - Resistor: Yes – special inductive resistor
  • - Centre Electrode: Nickel
  • - Centre Electrode Core: Copper
  • - Electrode Type: Surface gap
  • - Conventional Ground Electrode: None
  • - Adjustable Gap: No
  • - Terminal Type: Solid post
  • - Sealing Washer: Yes

Compatible Outboard Motors

  • Mercury Outboards
  • - Mercury V-135 – 135 HP – serial 0A904646 and up
  • - Mercury V-150 / 1500 Carb – 150 HP – serial 4868998–0G960499
  • - Mercury V-150 EFI – 150 HP – serial 0D082000–0G960499
  • - Mercury V-150 XR2 – 150 HP
  • - Mercury V-150 XR4 – 150 HP
  • - Mercury V-150 XR6 – 150 HP
  • - Mercury V-150 Magnum II – 150 HP
  • - Mercury V-150 Magnum III – 150 HP
  • - Mercury V-175 / 1750 Carb – 175 HP – serial 4301235–0G960499
  • - Mercury V-175 Carb – Australian models – serial 8058870 and up
  • - Mercury V-175 EFI – 175 HP – serial 0D000750–0G960499
  • - Mercury V-200 / 2000 Carb – 200 HP – serial 4839034–0G960499
  • - Mercury V-200 Carb – Australian models – serial 8061595–8065672
  • - Mercury V-200 EFI – 200 HP – serial 0C100861–0G960499
  • - Mercury V-220 Laser – 220 HP – serial 0B117316 and up
  • - Mercury V-225 2.4L – 225 HP – serial 5628028 and up
  • Mercury's application data identifies 33-14103568 / NGK BUZ8H for these engines. Later versions of several of these engine families changed to BPZ8HS-10, BPZ8H-N-10, IZFR5G or other plugs, making the serial-number ranges important.

Mariner Outboards

  • - Mariner 50 HP – 1992 onwards, selected 2-stroke models
  • - Mariner 60 HP – 1992 onwards, selected 2-stroke models
  • The Mariner application guide specifically identifies BUZ8H for these applications. Other Mariner 50/60 HP variants use BUHW, BUHW-2, BPZ8H-N-10 or conventional plugs, so the model/year must be confirmed.

Johnson Outboards

  • - Johnson 200 HP – 1976–1983
  • - Johnson 200 HP COM – 1992 onwards, selected applications
  • NGK's own part finder specifies BUZ8H, 14 mm thread and 12.7 mm reach for these engines.

Cross-Reference Spark Plugs & Part Numbers

  • - NGK: BUZ8H
  • - NGK Stock Number: 7447
  • - Mercury / MerCruiser: 33-14103568
  • - Mercury: 14103568
  • - Champion: QL16V
  • - Champion: QL6VC
  • - Champion: 886M

Important Fitment Information

  • The BUZ8H is a surface-gap spark plug, so it should not be manually gapped like a conventional J-gap plug. The apparent firing distance shown in some specification systems is a characteristic of the surface-gap design rather than a conventional bend-to-adjust electrode gap.
  • Do not confuse
  • - BUZ8H – resistor surface-gap, NGK heat range 8
  • - BU8H – non-resistor surface-gap
  • - BUZHW – different resistor surface-gap application
  • - BUZHW-2 – different surface-gap application
  • - BPZ8HS-10 – projected conventional electrode, 1.0 mm gap
  • - BPZ8H-N-10 – different projected plug specification

Signs the Spark Plug Needs Replacing

  • - Difficult starting
  • - Engine misfire
  • - Rough running
  • - Hesitation under acceleration
  • - Loss of high-RPM performance
  • - Reduced engine power
  • - Excessive carbon deposits
  • - Oil fouling
  • - Corrosion
  • - Damaged ceramic insulator
  • - Excessive wear or damage around the surface-gap firing area

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