Engine Balance Cheat Sheet

Small Block Chevrolet

  • Gen1- 86 and Prior- (267/283/302/305/327/350) Internal balance
  •  
  • 400 SBC-External Balance
  •  
  • 87-95 (Includes LT1/LT4 Opti-spark) Internal Front/External Rear
  •  
  • 96-2000- Internal Front/External Rear
  •  
  • LS Engines-Internally Balanced
  •  
  • LT Engines- (2016+ model year) Internal Balance 

 

Big Block Chevrolet

 

  • W Series (348-409) Internally Balanced
  •  
  • 396-427 Internal Balanced
  •  
  • 454-502- External Balance 
  •  
  • 572- Internal Balance
  •  
  • GEN VI
  •  
  • L29/L21- External Balance
  •  
  • GEN VII
  •  
  • L18-External Balance
  •  
  • 8.0L Vortec- Internal

 

Pontiac

 

  • 326-455- Internal

  

Oldsmobile Small Block

 

  • 260-307-330-350-403- External

 

Oldsmobile Big Block

  • 400-425-455- External

 

AMC

 

  • Gen 1 (to 1966)
  •  
  • 250-287-327-External
  •  
  • Gen 2 (1966-1970)
  •  
  • 290-343-390-External
  •  
  • Gen 3 (1970-1991)
  •  304-360-390-401- External (Though they share the same crank flange, 304, 360, and 401 do not interchange)

 

Chrysler Small block

 

  • 318 A (POLY)-Internal
  •  
  • 273-318-340 (340 to 1971 Steel Crank) LA-Internal
  •  
  • 340 (1972 up w/Cast Crank) External
  •  
  • 360-External

 

Chrysler MAGNUM Engine

 

  • 318 (5.2) Internal
  •  
  • 360 (5.9) External
  •  
  • 5.7l, 6.1l, 6.2l, 6.4l HEMI- Internal

 

 

Chrysler Big Block

 

  • B Engines 1958-1971 Internal (Forged Crank) , 1972-1978 External (Cast Crank)
  •  
  • 350-361-383-Internal
  •  
  • 400- External
  •  
  • RB Engines 1958-1971 Internal (Forged Crank), 1972-1978 External (Cast Crank)
  •  
  • 383-413-426- Internal
  •  
  • 426 Wedge- Internal
  •  
  • 440 (1966- 1971) Forged Crank- Internal
  •  
  • 440 (1972- 1978) Cast Crank- External
  •  
  • ***440 Six Pack- External*** (Forged Crank w/Heavy Rods)
  •  
  • 426 HEMI- Internal

 

 

Ford Small Block

 

  • 289-302 - Ext 28oz
  •  
  • 302 HO- Ext 50oz
  •  
  • 351W- Ext 28oz
  •  
  • 351C- Ext 28oz
  •  
  • 351M/400- Ext 28oz
  •  

 

Ford Big Block

  •  
  • 429-460- Internal

 

Ford Y Block

 

  • 239-256- Internal (1954 Cars Only- Cleveland Blocks)
  •  
  • 272-292-312- External
  •  
  • 239-256- External (Trucks only- Dearborn Blocks)

 

 

Ford FE

 

  • 332-352-360-390-406-427- Internal
  •  
  • 410- External
  •  
  • 428- External
  •  
  • 330-361-391- External
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