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Crankshaft FAQ

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John
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Crankshaft FAQ

Post by John » February 18th, 2008, 7:31 pm

The 258 (4.2) crankshafts we use as the basis of most of our stroker builds can be found in two basic forms, twelve or four counterweights. The heavier 66 lb., 12 counterweight, with it’s 64mm nose, was in use from 1971 to 1981 and the lighter, 46 lbs., four counterweight crankshafts, in use from 1982 through 1990. This four-counterweight crankshaft can be found in early form with a 64mm nose or in the later 54 mm nose. Both 258 crankshafts use a 3.895" stroke. Many feel the 12-counterweight design is the stronger of the two.

All 4.0L crankshafts utilize the same main journal and rod journal sizes as the AMC crankshafts. All 4.0L
Crankshafts are nodular iron, use only 8 counterweights and have the 54mm nose. The stroke in the 4.0L engine is 3.44".
---------------------------------------------------------------------------------------------------------------------------
Year_____Crank Casting No._Part No.
1971_____3199738________4488665 For Borg Warner automatic, small pilot
1972-74__3214723________8120508 12 counterweights, 66lb, 64mm nose
1975-79__3214723________8125450 12 counterweights, 66lb, 64mm nose
1980_____3214723________8132619 12 counterweights, 66lb, 64mm nose
1981-86__3235477________3235444 4 counterweights, 46lb, 64mm nose
1987-90__3727___________53005535 4 counterweights, 46lb, 54mm nose

258 block casting numbers
70-'72: 3199962
'73-'74: 3218618, 3222380, 3213867
'75-'79: 3227445, 3224098
'80: 3235077
'81-'89: 3235444
John

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Muad'Dib
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Re: Stroker Crankshaft FAQ

Post by Muad'Dib » February 18th, 2008, 8:59 pm

Moved / renamed your post... hope it looks ok to you!

Question..

You said 12 counterweight is said to be the stronger of the options... but its heavier right?

The other option is the 4 counterweight... which is lighter.

Does lighter = More HP/Torque?

If so, does the strength difference superseed the difference in hp/torque gains?

Sorry for the newbish questions.
If it feels right, then STROKE it!
You're lucky that hundred shot of CAPS LOCK didn't blow the welds on the forum!!

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John
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Re: Stroker Crankshaft FAQ

Post by John » February 19th, 2008, 2:36 am

"You said 12 counterweight is said to be the stronger of the options... but its heavier right?
The other option is the 4 counterweight... which is lighter.
Does lighter = More HP/Torque?
If so, does the strength difference superseed the difference in hp/torque gains?"

Good questions! The 20 lb. difference in weight makes the 12 weight crankshaft more self dampening to vibrations, not that the 4 weight is prone to it. (We will leave that job to our camshaft arrangement).

HP/Torque will be the same with either crankshaft. The stroke provided is the primary input to the HP/Torque equation.

The strength difference comes into play rarely, extreme builds/use. now the additional weight would be advantageous for a rock crawler needing to hold low rpm and the lighter crank will have a slight edge for a rally type application with a automatic transmission. For most builds they are completely interchangeable.
John

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Re: Stroker Crankshaft FAQ

Post by Flash » February 21st, 2008, 6:05 am

Muad'Dib wrote:Moved / renamed your post... hope it looks ok to you!

Question..

You said 12 counterweight is said to be the stronger of the options... but its heavier right?

The other option is the 4 counterweight... which is lighter.

Does lighter = More HP/Torque?

If so, does the strength difference superseed the difference in hp/torque gains?

Sorry for the newbish questions.

If 2 stoker were build identical in every way.......Except the cranks (12 CW v 4 CW)

In a drag race the 4 CW would win every time...........not because it make more HP but because it can spin up quicker.

On the other side of the coin, in low speed (Crawl speed) Traveling a 0+ speed and encounter a bolder with you from tire.
The 4 CW stroker will stall the eng before you can give it enough throttle to get over it.
The twelve CW stroker will hit the rock and climb right over with out touching the go peddle........ not because it has more HP but because of more Rotating weight and become harder to slow down, allowing the next cylinder to fire and the next......and up and over it go's

Flash
89 XJ with 300,000 on the original eng

"I've also never completed a motor, yet. My mouth (fingers) is also writing checks my ass can't cash."

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Muad'Dib
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Re: Crankshaft FAQ

Post by Muad'Dib » February 21st, 2008, 8:55 am

Great explaination thank you!
If it feels right, then STROKE it!
You're lucky that hundred shot of CAPS LOCK didn't blow the welds on the forum!!

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Muad'Dib
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Posts: 1486
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Re: Crankshaft FAQ

Post by Muad'Dib » July 9th, 2008, 12:32 pm

CRANKSHAFTS
The 199 used 12 counterweights and was made of cast pearlitic malleable iron. A steel crankshaft is rumored to exist (and would be very rare), but is supposedly stronger, and has been reported as the crank used in Barney Navarro's 640 HP turbocharged 199 Indy car engine. It is very doubtfull that a steel crankshaft was ever made, due to the original 232 engine design being based on a iron crankshaft. All 199 crankshafts use a 3.000" stroke.

A plethora of 232 cranks have been used. All are made from pearlitic malleable iron, and use a 3.500" stroke. The original 232 crankshaft was designed with 4 counterweights, and met all design requirements, but was produced with 4 counterweights in an effort to increase engine smoothness. I believe the crankshafts were changed to a 12 counterweight design shortly after the engine's introduction in order to increase smoothness further. No steel crankshafts were produced; the design concept of the 232 was based on a cast iron crankshaft as a means of reducing cost.

The 258 cranks come in two basic varieties: standard and lightweight. The standard cranks were used from 1971 to 1981 and use 12 counterweights. The lightweight cranks were used from 1982 on and use only 8 counterweights. Although heavier, the 12 counterweight cranks have been proven stronger with countless hours of SCCA car testing. The early 258 crank was designed for use with the Borg Warner automatic, and requires an adapter to be used with a Torqueflite automatic. The 258 crankshafts use a 3.895" stroke.

All 4.0L crankshafts utilize the same main journal and rod journal sizes as the AMC crankshafts. All 4.0L cranks are nodular iron, and use only 8 counterweights. The stroke used in the 4.0L engine is 3.44".

Code: Select all

MODEL YEAR  ENGINE   PART #   CASTING #    NOTES                          
  1965       199    ???????    3172216     For Borg Warner automatic
  1965-66    199    3173430    3173429     For Borg Warner automatic
  1967       199    3208626    3173429     For Borg Warner automatic
  1968-70    199    3208793    3173429     For Borg Warner automatic


  1964       232    ???????    3160035     8 Counterweights, for Borg Warner auto
  1964-65    232    3172217    3172218     For Borg Warner automatic
  1966       232    3207019    3172218     For Borg Warner automatic
  1967       232    3208627    3172218     For Borg Warner automatic
  1968-71    232    3208794    3172218     For Borg Warner automatic
  1972-74    232    8120507    3214722     For Torqueflite automatic
  1975-79    232    8125449    3214722     For Torqueflite automatic


  1971       258    4488665    3199738     For Borg Warner automatic
  1972-74    258    8120508    3214723     For Torqueflite automatic
  1975-79    258    8125450    3214723     For Torqueflite automatic
  1980       258    8132619    3214723     For Torqueflite automatic
  1981-86    258    ???????    3235477     Lightweight (4 counterweights) crank
  1987-88    258    83503326   3727        Lightweight (4 counterweights) crank


  1987-90    4.0L   83503409   unknown     
  1991       4.0L   83507107   unknown     
  1992       4.0L   4638952    unknown     
  1993-96    4.0L   4728882    unknown    
  1997       4.0L   4864726    unknown 


Part numbers listed starting with 81XXXXX are assembly numbers, and are presumed to include bearings. Other part numbers may represent either original part numbers, superceded part numbers, or both. Casting numbers are visible on the crankshaft. Casting numbers and part numbers may or may not be the same from year to year.
If it feels right, then STROKE it!
You're lucky that hundred shot of CAPS LOCK didn't blow the welds on the forum!!

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