440 internal/external balance questions, advice

[RestifiedBee]

I have a '69 Super Bee. When I got it (over 20 yrs ago) it had an 1964 dated 426 wedge (steel crank) with the original 727 auto. It ran and drove fine. The block froze and cracked. I found a running 440 (cast crank) out of '72 Imperial, swapped it out. When changing the parts over, my crank pulley wouldn't bolt up to the balancer, so I swapped it out for one from the 426. I didn't change the flex plate. Now I have a vibration/hum above 30 mph. I've done some research, correct me if I'm wrong, I need to change the balancer, for one externally balanced and the flex plate also for an externally balanced one that will let me keep the same torque convertor like a B&M 10237

 

[NOSTRT980]

converter needs to be external balance also

 

[Cranky]

I'm not sure about the B&M number but yeah, you can get the flex plate with the pie cut in it and it'll do the same as a weighted converter. Fact is, I don't think you can get a weighted converter anymore.
https://www.google.com/?gws_rd=ssl#q=external+balance+flexplate+for+mopar

Or you can do this....

https://www.google.com/?gws_rd=ssl#q=weighted+converter+for+mopar

 

[RestifiedBee]

I'm not sure about the B&M number but yeah, you can get the flex plate with the pie cut in it and it'll do the same as a weighted converter. Fact is, I don't think you can get a weighted converter anymore.
https://www.google.com/?gws_rd=ssl#q=external+balance+flexplate+for+mopar

Or you can do this....

https://www.google.com/?gws_rd=ssl#q=weighted+converter+for+mopar

I was told the same about the flexplate/converter. just wanted some more input. Thanks

 

[IQ52]

Are you sure it's a cast crank? Most '72 440's were forged crankshafts.

 

[RestifiedBee]

Yep. Had to swap the oil pan and pickup also.

 

[69Bee]

Oil pan will be different for the Imperial, and you fixed that. Either the torque converter or the flex plate needs to change. You have to remove the tranny anyway, so it would be your choice. The flex plate would probably be the easiest to do (10 bolts and no fluid to mess with). Here is a link for the B&M from Mancini, and just check with transtar for a converter if you want to that way. I got one for my 360 truck, and it was only about $65.

http://www.manciniracing.com/19latexbal38.html
http://www.summitracing.com/parts/bmm-10237

These are for the cast crank, and not the 6-Pak motor which is steel and external balance too.

 

[Meep-Meep]

Yes, the cast crank will require the externally balanced damper and felx plate or converter (not both).