258 crankshaft question for 86 jeep comanche
Posted: October 21st, 2011, 10:36 am
I am building a 4.7 Stroker for my Jeep Comanche, I recently swapped out my 2.8 V6 for a 4.0 Inline 6, but I am having a hard time find a 258 crankshaft for my stroker build. I found the specs below on such a crankshaft but I was wondering what vehicle they are talking about for the later model 258 crankshaft with the snout already shortened. I also was wondering if the weight difference will affect my build and if it matters if I use the later model heavier crank or the newer model light crank. In my area I cant seem to find a 258 crankshaft from a earlier model jeep and wanted to know what vehicles carry the later model crank that is already shortened
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".
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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
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
) if youre set on the 4 cwt short nose look for later model eagles (those 4wd car things) or gremlins, spirits, concords, eagles, hornets, and a few others will have the 12 cwt long nose version, 1980 or older.