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Mercury V6 2-Stroke Block ID Chart

  • Writer: Mike Hill
    Mike Hill
  • Sep 7, 2023
  • 3 min read

Updated: Jul 1

Ultimate Guide to Mercury Marine & Mercury Racing V6 Blocks (2.0L, 2.4L, 2.5L)
Ultimate Guide to Mercury Marine & Mercury Racing V6 Blocks (2.0L, 2.4L, 2.5L)

Mercury Marine and Mercury Racing 2-stroke V6 outboard engines—spanning 2.0, 2.4, and 2.5 liters—are iconic in performance boating. This guide decodes the factory-stamped double-letter block codes (like EE, FF, NN, etc.) and explains how to identify them, what makes each unique, and which models they belong to.


It combines verified Mercury documentation with enthusiast research to provide the most complete reference available.


Where to Find Block Codes and Build Date Stamps


  • Block Code (ID Letters): Stamped into the port-side flange, where the block halves meet, typically in the upper third of the block. Codes like "EE", "KK", or "SS" are found in this location and are critical for identification.

  • Date Stamp: Usually located on the port side, side of cylinder #2, often near the timing arm boss. Appears as a stamped date in MM/DD/YY format, e.g., "08 06 98" for August 6, 1998.


Detailed Block Code Reference Chart (by Displacement)


Mercury 2.0 Liter Blocks


  • V - Champ: Formula 1 racing block used in tunnel boats; very high port timing, 240–260+ HP, Bridgeport exhausts, race fuel only.

  • AA - 150 HP Fat Block: Recreational use, uses 2.5L casting with 2.0L sleeves (thicker cylinder walls). Moderate port timing and idle reliefs for smoother idle.


Mercury 2.4 Liter Blocks


  • G - XR4 150 HP: 2.4L block detuned to 150 HP with smaller carbs and lower port timing. Strong midrange, used in bass boats.

  • DD - 200 HP: Standard 2.4L 200 HP engine. Chrome-lined bores, 7-petal reeds, no idle reliefs. Factory tuning for prop-rated 200 HP.

  • ZZ - Bridgeport 225-240 HP: Racing block with bridged exhaust ports and finger porting. Known for high RPM and no oil injection.


Mercury 2.5 Liter Blocks


  • F - 200 HP (1991 Only): First-gen 2.5 block, 7-petal reeds, smaller chest, precursor to EE/FF.

  • EE - 200 HP Small Chest: smaller exhaust chest for improved low RPM torque. Includes idle relief slots, uses 5-petal reeds.

  • FF - 200 HP Large Chest: Larger exhaust chest for better top-end power. No idle reliefs, slightly more aggressive port timing.

  • CC - 175 HP: Similar to EE but with smaller exhaust ports and idle reliefs, resulting in smoother idle and lower compression.

  • BB - 150 HP XR6: Full 2.5L displacement, detuned with smaller carbs and small exhaust ports. Strong torque and great durability.

  • KK - 245 HP Carb: Carbureted version of the 260 EFI block. High compression, finger ports, 7-petal reeds. Pure racing block.

  • NN - 225 HP ProMax: Consumer high-performance block with 7-petal reeds, oil injection, higher compression, and slightly detuned 260 ports.

  • LL / PP - 260 HP EFI: Mercury Racing motor. Open chest, finger ports, no idle reliefs, 7-petal reeds, premix only. LL is the later big-bearing variant; PP may indicate earlier small-bearing version.

  • QQ - 280 HP EFI: Successor to 260 with optical digital ignition (ODI), 16-amp charging, modern ECU, top-guided pistons.

  • SS - 300 HP Drag: Ultimate race block with extreme porting, 11,500 RPM limit, single-ring pistons, no charging system, high compression. Drag or F1 use only.

  • JJ - 200 HP Tall Deck: 2000–2005 service block with taller deck casting of O-Ring heads. Small chest, oil-injected, durable alternative to EE/FF blocks.


Mercury Block ID Quick Reference - Key Differences

Code

Displacement

HP

Chest

Idle Relief

Reeds

Use Case

V

2.0

260+

Open

No

7-petal

Racing (F1)

AA

2.0

150

Std

Yes

5-petal

Fishing

G

2.4

150

Std

No

5-petal

Bass Boats

DD

2.4

200

Std

No

7-petal

General Use

ZZ

2.4

240

Bridge

No

7-petal

Racing

F

2.5

200

Large

No

7-petal

TransitionModel

EE

2.5

200

Small

Yes

5-petal

Low End Power

FF

2.5

200

Large

No

5-petal

Hot Rod Fishing

CC

2.5

175

Small

Yes

5-petal

Trolling

BB

2.5

150

Std

No

5-petal

XR6 Bass Fishing

KK

2.5

245

Open

No

7-petal

Racing (Carb)

NN

2.5

225

Open

No

7-petal

Hi-Perf

LL

2.5

260

Open

No

7-petal

Racing EFI

PP

2.5

260

Open

No

7-petal

Racing EFI

QQ

2.5

280

Open

No

7-petal

Offshore Racing

JJ

2.5

200

Small

No

5-petal

O-Rings Heads


Tips for Marine Techs & Engine Builders


  • Always confirm bore diameter:

    • 2.0L = 3.125"

    • 2.4L = 3.375"

    • 2.5L = 3.5"

  • Use stamped block codes to identify horsepower range and features.

  • Blocks with idle reliefs idle smoother but have reduced compression.

  • High-performance blocks (KK, NN, LL, SS) omit oil injection and require pre-mix fuel.

  • Early 260 blocks (PP) had smaller top bearings; later (LL) blocks have 4-bolt mains and larger bearings.


This guide clarifies the core differences between Mercury and Mercury Racing blocks. Whether you're building a ProMax sleeper or restoring a Drag motor, identifying your block correctly is key to selecting the right parts and tuning strategy. Double-letter code = your block’s DNA.






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Guest
Jun 27
Rated 5 out of 5 stars.

really cool hard to find chart.i have only seen a few on scream and fly but not this good.thanks

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