How much can you grind a 440 steel crank down?
#1904916
09/02/15 02:22 PM
09/02/15 02:22 PM
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Joined: Jul 2007
Posts: 732
eastern,Ky
70RT Charger
OP
super stock
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OP
super stock
Joined: Jul 2007
Posts: 732
eastern,Ky
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Tore my motor apart. Everything looked great unil I started taking the pistons out. I noticed what appeared to be a couple scratches on the journals. You can't feel them by rubbing your finger on them but you can catch them with your finger nail. Don't know what caused the scratches but this motor has been put together since 89 but has been setting the last several years. I don't think the crank has ever been touched, just hoping it's still good.
Last edited by 70RT Charger; 09/02/15 02:23 PM.
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Re: How much can you grind a 440 steel crank down?
[Re: 70RT Charger]
#1904935
09/02/15 02:55 PM
09/02/15 02:55 PM
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Joined: Mar 2008
Posts: 5,746
Ontario, Canada
Dodgem
master
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master
Joined: Mar 2008
Posts: 5,746
Ontario, Canada
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Probably got scratched installing pistons and rods. polish the crank and go if its right size. next time put 3/8 hose over the bolts so you don't scratch it. Could have been a touch of debris too.
(bin there done that)
Last edited by Dodgem; 09/02/15 02:56 PM.
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Re: How much can you grind a 440 steel crank down?
[Re: 70RT Charger]
#1904937
09/02/15 02:58 PM
09/02/15 02:58 PM
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Joined: Mar 2003
Posts: 4,848
Memphis
HemiRick
master
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master
Joined: Mar 2003
Posts: 4,848
Memphis
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Just about any crankshaft can be be turned up to .030 under size
Take care,
Rick
68 Coronet R/T 440 & 68 Charger 528 Hemi,and 5 Challengers! 6 cyl, 318, 360, 383, 451
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Re: How much can you grind a 440 steel crank down?
[Re: Dodgem]
#1904954
09/02/15 03:16 PM
09/02/15 03:16 PM
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Joined: Jul 2007
Posts: 732
eastern,Ky
70RT Charger
OP
super stock
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OP
super stock
Joined: Jul 2007
Posts: 732
eastern,Ky
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Probably got scratched installing pistons and rods. polish the crank and go if its right size. next time put 3/8 hose over the bolts so you don't scratch it. Could have been a touch of debris too.
(bin there done that)
I didn't assemble the motor but when I tore it apart I put the 3/8 hose on the rod bolts. Looks like debris scratches to me. Thanks
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Re: How much can you grind a 440 steel crank down?
[Re: HemiRick]
#1904955
09/02/15 03:18 PM
09/02/15 03:18 PM
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Joined: Jul 2007
Posts: 732
eastern,Ky
70RT Charger
OP
super stock
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OP
super stock
Joined: Jul 2007
Posts: 732
eastern,Ky
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Just about any crankshaft can be be turned up to .030 under size Ok thanks. I think I should be good then. I was going to start looking for another but I'll wait and hopefully my machinist says I'm good. Thanks
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Re: How much can you grind a 440 steel crank down?
[Re: 70RT Charger]
#1904958
09/02/15 03:19 PM
09/02/15 03:19 PM
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Joined: Jan 2003
Posts: 684
St. Charles, MO.
Slingshot383
mopar
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mopar
Joined: Jan 2003
Posts: 684
St. Charles, MO.
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You can turn the journals down to Honda size if you want, 2.2 big block Chevy is common to gain a little stroke.
1994 Undercover Chassis 125" altered
stack injected big block, soon blown and injected
Member of The Torque and Recoil Club
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Re: How much can you grind a 440 steel crank down?
[Re: Slingshot383]
#1904976
09/02/15 03:35 PM
09/02/15 03:35 PM
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Joined: Jul 2007
Posts: 732
eastern,Ky
70RT Charger
OP
super stock
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OP
super stock
Joined: Jul 2007
Posts: 732
eastern,Ky
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You can turn the journals down to Honda size if you want, 2.2 big block Chevy is common to gain a little stroke. Really? Is this a common practice and how much does it help you power wise.
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Re: How much can you grind a 440 steel crank down?
[Re: 70RT Charger]
#1905012
09/02/15 04:17 PM
09/02/15 04:17 PM
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Joined: Aug 2013
Posts: 369
Indy
496 A-body
enthusiast
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enthusiast
Joined: Aug 2013
Posts: 369
Indy
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You can turn the journals down to Honda size if you want, 2.2 big block Chevy is common to gain a little stroke. Really? Is this a common practice and how much does it help you power wise. Used to be very common before forged stroker cranks were readily available. How much it would help you power wise depends on a lot of things, but you could gain .175 stroke (theoretically but not likely)
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Re: How much can you grind a 440 steel crank down?
[Re: 496 A-body]
#1905167
09/02/15 07:07 PM
09/02/15 07:07 PM
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Joined: Jan 2003
Posts: 16,376
dogdays
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 16,376
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A 3.75" stroke crank with 2.375" rod journals will offset grind to a 3.91" stroke with bigblock chevy 2.200" rod journals.
This means you need new BBC style connecting rods and pistons with 0.990 BBC-style pins. The gain in cubic inches is small, 17 cubic inches, and I don't think you could find shelf stock pistons for it. Don't even think about it.
The 3.91 crank makes a nice addition to a 400 block because with the mains ground down to 2.625 to fit in the B block, it is now around 470 cubic inches in a package that looks like a 383.
If you're going to all that trouble with a 440 it makes sense to buy a stroker kit and really go big, like 4.25" stroke. The only difference will be the cost difference between regrinding the crank and the cost of a new stroker crank, which usually runs about $750 for one of the decent varieties of import forged stroker cranks.
If you just want to reuse your crank, etc, it can go 0.040 or 0.050 under depending on which rod bearings you can find. Sounds like the imperfection can be polished off, so it may not need to be ground at all.
Too much information, maybe!
R.
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Re: How much can you grind a 440 steel crank down?
[Re: dogdays]
#1905253
09/02/15 09:23 PM
09/02/15 09:23 PM
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Joined: Jul 2007
Posts: 732
eastern,Ky
70RT Charger
OP
super stock
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OP
super stock
Joined: Jul 2007
Posts: 732
eastern,Ky
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A 3.75" stroke crank with 2.375" rod journals will offset grind to a 3.91" stroke with bigblock chevy 2.200" rod journals.
This means you need new BBC style connecting rods and pistons with 0.990 BBC-style pins. The gain in cubic inches is small, 17 cubic inches, and I don't think you could find shelf stock pistons for it. Don't even think about it.
The 3.91 crank makes a nice addition to a 400 block because with the mains ground down to 2.625 to fit in the B block, it is now around 470 cubic inches in a package that looks like a 383.
If you're going to all that trouble with a 440 it makes sense to buy a stroker kit and really go big, like 4.25" stroke. The only difference will be the cost difference between regrinding the crank and the cost of a new stroker crank, which usually runs about $750 for one of the decent varieties of import forged stroker cranks.
If you just want to reuse your crank, etc, it can go 0.040 or 0.050 under depending on which rod bearings you can find. Sounds like the imperfection can be polished off, so it may not need to be ground at all.
Too much information, maybe!
R. Definitely not to much info. I've considered a stroker kit but I really need to spend the extra money somewhere else and really don't want the 400 in my Charger so Ill jut let my machinist take care of my crank. I really appreciate the info though.
Last edited by 70RT Charger; 09/02/15 09:23 PM.
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Re: How much can you grind a 440 steel crank down?
[Re: 70RT Charger]
#1905328
09/02/15 10:56 PM
09/02/15 10:56 PM
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Joined: Aug 2003
Posts: 43,126
Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,126
Bend,OR USA
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I've built several 3.91 stroke RB motors, I'm almost positive that KB, Icon brand, makes three different shelf pistons for this combination using a 7.100 long BB Chevy forged H beam rod , dish, reverse dome, (half a dish) and flat top with valve reliefs so you can get the compression ratio you want  that combination rocks in all configurations 
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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