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3.91 stroke BB crank #1340563
11/24/12 02:33 PM
11/24/12 02:33 PM
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Real North Cal.
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66er Offline OP
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Which crank would be stronger \ last longer. A offset ground factory steel crank with the mains ground to 400 size, or a chinese 4340 forged crank

Re: 3.91 stroke BB crank [Re: 66er] #1340564
11/24/12 02:43 PM
11/24/12 02:43 PM
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Thumperdart Offline
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Quote:

Which crank would be stronger \ last longer. A offset ground factory steel crank with the mains ground to 400 size, or a chinese 4340 forged crank


My 413 cut crank is going on over 13 years................


72 Dart 470 n/a BB stroker street car `THUMPER`...Check me out on FB Dominic Thumper for videos and lots of carb pics......760-900-3895.....
Re: 3.91 stroke BB crank [Re: 66er] #1340565
11/24/12 02:51 PM
11/24/12 02:51 PM
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Bend,OR USA
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Cab_Burge Offline
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Quote:

Which crank would be stronger \ last longer. A offset ground factory steel crank with the mains ground to 400 size, or a chinese 4340 forged crank


Probally 4340, I can't remember the type and number of the stock forged steel cranks Mopar put in the original HP and non HP motors. I have had several stock forged steel crank offset ground and then heat treated, they last I have also had a Chinese RB 4.150 stroke 4340 crank offset ground to 4.300 stroke with BB chevy rod journals and cut the counter weigts and mains down to fit in my 400 block, I had it reheattreated afterwards also 5 yrs whupping on it so far Both ways will work


Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: 3.91 stroke BB crank [Re: Thumperdart] #1340566
11/24/12 02:53 PM
11/24/12 02:53 PM
Joined: Feb 2005
Posts: 370
Real North Cal.
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66er Offline OP
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66er  Offline OP
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Quote:

Quote:

Which crank would be stronger \ last longer. A offset ground factory steel crank with the mains ground to 400 size, or a chinese 4340 forged crank


My 413 cut crank is going on over 13 years................





Ya, I read your post yesterday. It caused me to think about having a back-up crank ground. I can get a good core cheap. How many RPMs do you turn yours?

Re: 3.91 stroke BB crank [Re: 66er] #1340567
11/24/12 03:10 PM
11/24/12 03:10 PM
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Thumperdart Offline
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Seems it likes 6800-7200 shift points and traps around 7200 but I`ve been as high as 7800 accidently but seems fine..........the crank was actually bent when Pettis found it so Jason flipped it around to the high spot, smacked it a few times with a chissel and sledge hammer and it`s still goin strong.........


72 Dart 470 n/a BB stroker street car `THUMPER`...Check me out on FB Dominic Thumper for videos and lots of carb pics......760-900-3895.....
Re: 3.91 stroke BB crank [Re: Thumperdart] #1340568
11/24/12 03:23 PM
11/24/12 03:23 PM
Joined: Feb 2005
Posts: 370
Real North Cal.
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66er Offline OP
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66er  Offline OP
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Quote:

Seems it likes 6800-7200 shift points and traps around 7200 but I`ve been as high as 7800 accidently but seems fine..........the crank was actually bent when Pettis found it so Jason flipped it around to the high spot, smacked it a few times with a chissel and sledge hammer and it`s still goin strong.........




Looks like you beat on yours harder that's me. I shift at 6500-6700 and out the end 6700. that a bad engine!

Re: 3.91 stroke BB crank [Re: 66er] #1340569
11/24/12 03:31 PM
11/24/12 03:31 PM
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Thumperdart Offline
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Could be because of the 275-280 dur @.050 that kills a bit of bottom end but charges nicely mid track on up.


72 Dart 470 n/a BB stroker street car `THUMPER`...Check me out on FB Dominic Thumper for videos and lots of carb pics......760-900-3895.....






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