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Marine & Outboard Spark Plugs

NGK V-Power Spark Plug BP8H-N-10 (4838)

SKU: GB-BP8H-N-10

$8.80
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The NGK BP8H-N-10 (Stock No. 4838) is a non-resistor V-Power spark plug designed for a wide range of 2-stroke marine outboards. Featuring a V-groove nickel centre electrode, M14 thread, 12.7 mm reach and 1.0 mm gap, it promotes reliable ignition and consistent combustion. It is widely specified for selected Mercury and Mariner outboards, with additional marine applications where BP8H-N-10 is specifically specified.

Key benefits

Key Benefits

  • - NGK V-Power spark plug
  • - V-groove nickel centre electrode
  • - Improved ignitability
  • - Copper-core construction
  • - Non-resistor design
  • - NGK heat range 8
  • - 1.0 mm / 0.040" gap
  • - Short-reach marine plug
  • - Flat gasket seat
  • - Used extensively in Mercury and Mariner 2-stroke outboards
  • - Direct replacement for Mercury 33-816737Q / 8167372 applications

Specifications & Dimensions

  • - Brand: NGK
  • - Part Number: BP8H-N-10
  • - NGK Stock Number: 4838
  • - Spark Plug Type: V-Power / standard nickel
  • - Thread Diameter: 14.0 mm / 0.551"
  • - Thread Size: M14
  • - Thread Reach: 12.7 mm / 0.500"
  • - Hex / Spanner Size: 20.8 mm / 13/16"
  • - Spark Gap: 1.0 mm / 0.040"
  • - NGK Heat Range: 8
  • - Seat Type: Flat / gasket
  • - Resistor: No – non-resistor
  • - Centre Electrode: Nickel, V-groove
  • - Electrode Configuration: Projected
  • - Terminal Type: Solid post
  • Compatible Outboard Motors

Mercury Outboards

  • - 6 HP – selected 2-stroke models
  • - 8 HP – selected 2-stroke models
  • - 9.9 HP – selected applications
  • - Super 15 HP – selected applications
  • - 18 HP XD – 1984–1985
  • - 20 HP 2-Stroke – 1986–2000
  • - 20 HP Jet – 1995–2000
  • - 25 HP – selected 1983–1992 models
  • - 25 HP 2-Stroke – 1993–2000
  • - 25 HP Sea Pro – selected 2-stroke models
  • - 25 HP XD – 1984–1986
  • - 30 HP 2-Cylinder 2-Stroke – 1995–2000
  • - 30 HP Sea Pro – 1995–2000
  • - 30 HP Jet, 3-Cylinder – 1998–2000
  • - 40 HP 2-Cylinder 2-Stroke – 1995–2000
  • - 40 HP 3-Cylinder 2-Stroke – 1998–2000
  • - 40 HP Sea Pro – selected models
  • - 40 HP Jet – selected models
  • - 45 HP Jet, 3-Cylinder – 1995–2000
  • - 50 HP 3-Cylinder 2-Stroke – 1991–2000
  • - 55 HP Sea Pro, 3-Cylinder – 1992–2000
  • - 60 HP 3-Cylinder 2-Stroke – 1991–2000
  • - 60 HP BigFoot – 1995–1997
  • - 60 HP Sea Pro – 1995–2000
  • - 80 HP Jet, 4-Cylinder – selected models
  • - 100 HP 4-Cylinder 2-Stroke – selected models
  • - 115 HP 4-Cylinder 2-Stroke – selected models
  • - 125 HP 4-Cylinder 2-Stroke – selected models

Mariner Outboards

  • - 6 HP 2-Stroke – 1992–2002
  • - 8 HP – 1993–2002
  • - 15 HP Marathon – selected models
  • - 20 HP – selected models
  • - 20 HP Jet
  • - 25 HP
  • - 25 HP Marathon
  • - 30 HP
  • - 30 HP Jet
  • - 30 HP Marathon
  • - 40 HP Marathon, 2-Cylinder – 1995–2002
  • - 45 HP Jet, 3-Cylinder – 1995–2001
  • - 50 HP 3-Cylinder, 849 cc – 1991–2001
  • - 55 HP Marathon – 1991–2002
  • - 60 HP
  • - 60 HP BigFoot
  • - 60 HP Marathon
  • - 80 HP Jet
  • - 100 HP – selected models
  • - 115 HP 4-Cylinder 2-Stroke – 1989–2002
  • - 125 HP – selected applications

Cross-Reference / OEM Part Numbers

  • - NGK: BP8H-N-10
  • - NGK Stock No.: 4838
  • - Mercury / MerCruiser: 33-816737Q
  • - Mercury / Mariner: 816737
  • - Mercury / Mariner: 8167372
  • - Resistor/suppressor alternative for applicable Mercury engines: 33-816837Q / NGK BPZ8H-N-10

Important Fitment Information

  • BP8H-N-10 should not be confused with BP8HS-10, B8HS-10, BR8HS-10 or BPZ8H-N-10.
  • Although several of these plugs share a 14 mm thread, heat range 8 and 1.0 mm gap, their electrode and suppression characteristics differ. Mercury's own application data commonly lists BP8H-N-10 as the standard plug and BPZ8H-N-10 as the suppressor alternative.
  • Exact model, cylinder configuration, production year and serial number should be checked. For example, not every Mercury 150 HP uses BP8H-N-10; published application charts specify other plugs for many 150 HP variants.

Signs the Spark Plug Needs Replacing

  • - Difficult starting
  • - Rough or unstable idle
  • - Intermittent misfire
  • - Loss of power
  • - Poor acceleration
  • - Increased fuel consumption
  • - Carbon fouling
  • - Oil fouling
  • - Worn or rounded electrodes
  • - Excessive electrode gap
  • - Corrosion around the plug shell
  • - Cracked ceramic insulator

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