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Mopar B/RB Crankshafts (stock)

Chrysler's "B" and "RB" engine crankshafts have two basic stroke dimensions. The "B" engine crankshaft uses a 3.380 inch stroke and the "RB" engine uses a 3.750 inch stroke. Main journal size also differs between the "B" and "RB" engines. The "B" engine uses a 2.625 inch main journals, the "RB" uses 2.750 journals. Both engines share the same 2.380 inch rod journals.
All early crankshafts are steel forgings. In 1971 Chrysler used a cast crank in low performance 383 engines. The use of cast iron crankshafts in 440's began in 1972. All cast cranks and certain forged steel cranks are externally balanced. These require the use of specially balanced harmonic dampeners, torque converters and flywheels. The appropriate components must be used to ensure that the reciprocating assembly is in balance. If an internally balanced crank is used with an external balanced converter or dampener (or vise- versa) a severe out of balance condition will occur. Externally balanced crankshafts can be internally balanced by adding a heavy metal called Mallory metal to the crank throws. 440's equipped with 3x2 barrel carbs were also externally balanced to compensate for heavier rods. They require the use of externally balanced dampeners and converters or flywheels.
Part# Engine Material  
2268114 383 4BBL Forged  
3462922 383 / 400 2BBL Cast Externally Balanced
3672000 400 4BBL Cast Premium Cast Crank  
2536983 67-71 440 4BBL Forged  
3512036 70-72 440 6BBL Forged Externally balanced
3671283 72-73 440 4BBL Forged  
3671242 73 440 4BBL Forged Balanced for different weight pistons
3751889 74 440 2&4 BBL Cast Externally balanced
3751899 74 440 HiPo Forged  
2406240 413/426 Max Wedge Forged Best RB crankshaft
Big Block Crankshafts Dampers
Part# Engine  
2658457 1958-1971 All B & RB engines
3512017 1970-1971 440 6BBL and '71 440 High Performance
3577180 1971 383 2 barrel (cast crank)
3614371 1972-1973  400 Forged Crank
3614374 1972-1973 400 Cast Crank
3614371 1972-1973 440 Standard Performance
3614372 1972-1973 440 High Performance
3577785 1974 440 Cast Crank
     
  72 and up B&RB dampers use a different pulley bolt pattern.