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Re: Scat 4" cast crank? Will it break?
[Re: mshred]
#905182
01/17/11 07:12 AM
01/17/11 07:12 AM
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Joined: Jan 2003
Posts: 32,394
Quicktree
I Win
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I Win
Joined: Jan 2003
Posts: 32,394
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Quote:
Gonna call BPE tommorow and see if they offer a kit based on their cranks, possibly one of the 4.125 or 4.250 cranks with 360 mains
better have a good block 
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Re: Scat 4" cast crank? Will it break?
[Re: B3422W5]
#905183
01/17/11 10:18 AM
01/17/11 10:18 AM
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Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
patrick
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
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Quote:
Quote:
by the time you get it balanced and finished you will have spent enough for a forged crank..
EXACTLY........
Few years back i broke a cast 4 inch stroker crank. I had upgraded my combo from high 10's to 10.30's and it broke after about 50 passes, and ruined the rest of my season. I learned the hard way to do it right the first time.
Like i love saying, spend the extra 500 bucks and get the good piece the first time. In the whole scheme of building a motor, 500 bucks is just a small fraction of the total build, so why scrimp, just wait till you can do it right, then you wont ever have to wonder 
to the cast crank's credit, B422W5, how many years did you run the cast crank, externally balanced in your 3400lb duster running 10.75-10.80? IIRC yours was a MP crank, which was made by SCAT...and I'd imagine your drag strip launching with slicks and a high stall converter would be as brutal, if not more so, than street driving a 4 speed with street tires.
as far as factory cast vs. SCAT 4" cast, hotroddave makes some good points, although the factory cast cranks are ductile (nodular) iron, so the continuous phase of the material is steel, not graphite, like it is in grey cast iron. the lack of filleted radii is offset by the fact it has more journal overlap due to the shorter stroke.
if you have no plans for further upgrades, I'd just run the cast crank, or even if you do have plans for further upgrades, it might be more cost effective to build a whole new motor in the future, because soon you're going to get close to the limits of the factory block....
1976 Spinnaker White Plymouth Duster, /6 A833OD
1986 Silver/Twilight Blue Chrysler 5th Ave HotRod **SOLD!***
2011 Toxic Orange Dodge Charger R/T
2017 Grand Cherokee Overland
2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)
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Re: Scat 4" cast crank? Will it break?
[Re: patrick]
#905185
01/17/11 12:40 PM
01/17/11 12:40 PM
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Joined: Jan 2005
Posts: 12,419
Kalispell Mt.
HotRodDave
I Live Here
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I Live Here
Joined: Jan 2005
Posts: 12,419
Kalispell Mt.
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Patrick that is a good point about the cast crank giving up about the same as the stock block. I have seen the stock crank break right along the groove on the journal but never seen a SCAT break on the overlap point. Mabey some of the guys who broke them can post up pics 
I am not causing global warming, I am just trying to hold off a impending Ice Age!
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Re: Scat 4" cast crank? Will it break?
[Re: patrick]
#905187
01/19/11 12:14 PM
01/19/11 12:14 PM
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Joined: Jan 2003
Posts: 11,721
Portage,michigan
B3422W5
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 11,721
Portage,michigan
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Quote:
Quote:
Quote:
by the time you get it balanced and finished you will have spent enough for a forged crank..
EXACTLY........
Few years back i broke a cast 4 inch stroker crank. I had upgraded my combo from high 10's to 10.30's and it broke after about 50 passes, and ruined the rest of my season. I learned the hard way to do it right the first time.
Like i love saying, spend the extra 500 bucks and get the good piece the first time. In the whole scheme of building a motor, 500 bucks is just a small fraction of the total build, so why scrimp, just wait till you can do it right, then you wont ever have to wonder
to the cast crank's credit, B422W5, how many years did you run the cast crank, externally balanced in your 3400lb duster running 10.75-10.80? IIRC yours was a MP crank, which was made by SCAT...and I'd imagine your drag strip launching with slicks and a high stall converter would be as brutal, if not more so, than street driving a 4 speed with street tires.
as far as factory cast vs. SCAT 4" cast, hotroddave makes some good points, although the factory cast cranks are ductile (nodular) iron, so the continuous phase of the material is steel, not graphite, like it is in grey cast iron. the lack of filleted radii is offset by the fact it has more journal overlap due to the shorter stroke.
if you have no plans for further upgrades, I'd just run the cast crank, or even if you do have plans for further upgrades, it might be more cost effective to build a whole new motor in the future, because soon you're going to get close to the limits of the factory block....
Actually, i didnt run that cast crank as long as you seem to remember.
I had the 416 built by Hensley, very mild. Ran it first year and it went 11.70's without that many passes at all. Over the winter upgraded a few things and it went 10.70,and 80's. The third season i put w5 heads on the shortblock and it let go( flat tappet, 11.8 compression. I probably had 150-170 passes on it when it let go that third year part way through. And as i said the first year it was ultra conservative. So not that many passes with real good power, and a good bit without much power at all( 500 horsepower maybe)
My point is, spend the money and get a good crank, and only have to do it once.
BTW, ALL the above passes were off the foot without a 2 step. I only went to a brake when i put the X block roller motor together after the crank broke in the above 416.
69 Dart GTS A4 Silver All steel, flat factory hood, 3360race weight
418 BPE factory replacement headed stroker, 565 lift solid cam
Best so far, 10.40 @127 1/4
1.41 best 60 foot
6.60 at 103.90 1/8
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Re: Scat 4" cast crank? Will it break?
[Re: B3422W5]
#905188
01/19/11 02:14 PM
01/19/11 02:14 PM
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Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
patrick
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
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my mistake, I thought you were running it 3 or 4 years before you upgraded to the W5's.....
1976 Spinnaker White Plymouth Duster, /6 A833OD
1986 Silver/Twilight Blue Chrysler 5th Ave HotRod **SOLD!***
2011 Toxic Orange Dodge Charger R/T
2017 Grand Cherokee Overland
2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)
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