83 258 crank in 79 258 block?

Message Topic Search Topic Options Post Reply Create New Topic Printable Version Translate Topic

   Howdy all. I have same question as I am looking at two donor 258s trying to sort best retrofit to a 1965 AMC Rambler Classic 770, 3-speed BW Flash-O-Matic.    

Question will any year 258 crankshaft bolt up to the 65 BW automatic?
I am going by these reference charts which seem be same but for reference notes:

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
  MODEL YEAR  ENGINE   PART # 
 CASTING #    NOTES                          

  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

My current choices:

1975 258 engine with block # H53218618 (which appears was used for the 232 as well as 258), owner could not see head # but I assume its from 1974/75 as block had 709A04that would make it a 258 built September 4, 1974.

1982 258 engine with block # EF3235444 and the head is 3241656. 

So 1975 is the 12 counterweight crankshaft 258 and the 1982 has 4 counterweight crankshaft 258.   

Again, can any year 258 be used with the earlier BW automatic?

Thanks for any help.

Author	Message Topic Search Topic Options Post Reply Create New Topic Printable Version Translate Topic
TallTex Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Apprentice Joined: Oct/26/2016 Location: Texas Status: Offline Points: 32	Post Options Post Reply Quote TallTex Report Post Thanks(0) Quote Reply Posted: Sep/11/2017 at 8:17pm
	Howdy all. I have same question as I am looking at two donor 258s trying to sort best retrofit to a 1965 AMC Rambler Classic 770, 3-speed BW Flash-O-Matic. Question will any year 258 crankshaft bolt up to the 65 BW automatic? I am going by these reference charts which seem be same but for reference notes: 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 MODEL YEAR ENGINE PART # CASTING # NOTES 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 My current choices: 1975 258 engine with block # H53218618 (which appears was used for the 232 as well as 258), owner could not see head # but I assume its from 1974/75 as block had 709A04that would make it a 258 built September 4, 1974. 1982 258 engine with block # EF3235444 and the head is 3241656. So 1975 is the 12 counterweight crankshaft 258 and the 1982 has 4 counterweight crankshaft 258. Again, can any year 258 be used with the earlier BW automatic? Thanks for any help.

DaemonForce Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Jul/05/2012 Location: Olympia, WA Status: Offline Points: 1070	Post Options Post Reply Quote DaemonForce Report Post Thanks(0) Quote Reply Posted: Sep/11/2017 at 8:19pm
	Seeing how the flexplate on my 71 Javelin has no counterbalance, it looks like a neutral balance plate. I'm starting to wonder if maybe the original Borg Warner components I have came from a early L6 AMC and then the rest got scrapped for FMX swap stuff. Why it ended up behind my 304 is beyond me.
	1971 Javelin SST American 304 2v \| FMX \| AM20-3.31 1983 American Limited Jeep 4(.7)L S-MPFI \| 1982 NWC T-5M (4.03/.76) \| Dana30IFS/35-2.72

farna Members Profile Send Private Message Find Members Posts Add to Buddy List Supporter of TheAMCForum Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19689	Post Options Post Reply Quote farna Report Post Thanks(1) Quote Reply Posted: Sep/25/2017 at 7:17am
	Only the 71 258 crank will accept the BW auto. There are differences in the crank flange. You might be able to bolt a 71 or earlier auto to a 72+ crank, just use the proper pilot bushing for the auto (the BW converter has a "nose" that goes into the crank pilot hole -- may have to have a bushing made). The flexplate will bolt up, but may not sit right on the flange. The center hole of the BW flexplate may need to be enlarged. You can't put a TF trans on a BW crank flange though, as the TF flexplate has to center properly on the flange, which is specifically made for the TF trans. Manual trannys will interchange, but you have to use the correct flywheel to mate to the flange.
	Frank Swygert

DaemonForce Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Jul/05/2012 Location: Olympia, WA Status: Offline Points: 1070	Post Options Post Reply Quote DaemonForce Report Post Thanks(0) Quote Reply Posted: Sep/25/2017 at 12:29pm
	Was there ever a 290/304 flexplate that had NO counterweights anywhere and bolted up to the BW auto? I'm starting to think the plate on my 304 might have been sourced from an early 232/258.
	1971 Javelin SST American 304 2v \| FMX \| AM20-3.31 1983 American Limited Jeep 4(.7)L S-MPFI \| 1982 NWC T-5M (4.03/.76) \| Dana30IFS/35-2.72

purple72Gremlin Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Charter Member Joined: Jul/01/2007 Location: Illinois Status: Offline Points: 16614	Post Options Post Reply Quote purple72Gremlin Report Post Thanks(0) Quote Reply Posted: Sep/25/2017 at 12:33pm
	All of the V8s have weights...not sure about the early 290s.

DaemonForce Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Jul/05/2012 Location: Olympia, WA Status: Offline Points: 1070	Post Options Post Reply Quote DaemonForce Report Post Thanks(0) Quote Reply Posted: Sep/25/2017 at 12:58pm
	Well I know the true beauty of these inline engines is that they're an easy turn and you don't need to do any filling with expensive metal when balancing. This on top of one solid cylinder bank, upright firing, zero vibration within the reasonable 600-4000 operating range make it natural for pretty much any neutral flexplate or flywheel. The V8 assemblies are different and while I have a deep vested interest in the L6 and V8 builds, I never got to see any of the early stuff aside from my screwball 71 Javelin.
	1971 Javelin SST American 304 2v \| FMX \| AM20-3.31 1983 American Limited Jeep 4(.7)L S-MPFI \| 1982 NWC T-5M (4.03/.76) \| Dana30IFS/35-2.72