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| How much does a bare slant crank weigh? https://www.slantsix.org/forum/viewtopic.php?t=25820 |
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| Author: | rock [ Mon Nov 12, 2007 3:03 pm ] |
| Post subject: | How much does a bare slant crank weigh? |
Guys, I am trying to help a forum member get a crankshaft. I can't find the weight of one in any of my books or notes, and have been stymied trying to get to a shipper with the crank because of work. Anyone have a close or actual weight on a bare, forged, small hub truck crank? Thanks rock '64d100 |
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| Author: | bwhitejr [ Mon Nov 12, 2007 4:11 pm ] |
| Post subject: | Slant Crank Wt |
IIRC one of them weighs 58 lbs. Doc know exactly what each of them weighs (forged vs cast). PM him bwhitejr |
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| Author: | Joshie225 [ Mon Nov 12, 2007 4:37 pm ] |
| Post subject: | |
The forged crank, excepting the early ones with the big counterweights, is 76 lbs. http://www.slantsix.org/articles/parts-matrix/jpg.htm |
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| Author: | sandy in BC [ Mon Nov 12, 2007 5:59 pm ] |
| Post subject: | |
I have a 65 forged crank that weighs 83 lbs. |
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| Author: | dakight [ Mon Nov 12, 2007 6:17 pm ] |
| Post subject: | |
Quote: I have a 65 forged crank that weighs 83 lbs.
I would believe that! They are back breaking, hernia popping heavy!
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| Author: | Doctor Dodge [ Mon Nov 12, 2007 7:32 pm ] |
| Post subject: | |
The early 'big counterweight crank is 83 lbs, later forged cranks are 76 lbs Cast cranks are closer to 70 lbs. DD |
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| Author: | 1974duster kev [ Wed Nov 14, 2007 6:41 pm ] |
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Question any benefit to different weight cranks correct me if i'm wrong 83lb early one =more rotating mass more torque and later lighter cranks more rpm/ horsepower? justr curious Thanks, Kevin |
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| Author: | DusterIdiot [ Wed Nov 14, 2007 7:16 pm ] |
| Post subject: | Kinda... |
Quote: 83lb early one =more rotating mass more torque and later lighter cranks more rpm/ horsepower?
Pretty close, the lighter rotating mass allows you to spool the engine up to higher RPM faster (Project Beater Valiant uses a 1979 Cast Crank engine and the crank was 8 lbs lighter than it's 1976 Forged crank buddy...I notice it can get to 4000 rpm quicker than the Hpak duster can with the '76 forged crank...) -D.Idiot |
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| Author: | BigBlockBanjo [ Fri Nov 16, 2007 8:07 pm ] |
| Post subject: | |
That there is some big weight difference! I wonder why the cast crank isn't more popular than it is. Compared to an early crank, a 16-lb lighter crank is amazing....considering that many engine builders spend big-bucks trying to save a few grams of rotating mass. 
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| Author: | DusterIdiot [ Fri Nov 16, 2007 9:13 pm ] |
| Post subject: | Bearings, et al... |
Quote: I wonder why the cast crank isn't more popular than it is.
The bearings are a bit on the skinny side (and the catings of the block aren't as 'quality' either), you also 'give back' some of the 'rotating weight' in the cast crank damper (absorbs some of the harmonics in the lighter assembly..how neutral balanced is that 'neutral balance'?)... I do believe that one of the racers (Will?) uses a cast crank engine (not sure if it's because they are cheap and common in case of 'grenading' or the lighter crank assembly...???)-D.Idiot |
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| Author: | BigBlockBanjo [ Fri Nov 16, 2007 9:38 pm ] |
| Post subject: | |
Hmmm....I understand about the bearings, but really, how many people have spit a crank out of their six?? (Forced Induction is different) About the balance, why couldn't a shop truly "neutral balance" the crank, so you could put a lighter balancer on it? Maybe even sleeve the snout & machine it for a 8 lb. lightweight job? lightened/balanced cast crank + Rattler damper =(-+19lb. less rotating mass) That's like a second faster in the 1/8! 
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| Author: | Doctor Dodge [ Sat Nov 17, 2007 9:50 am ] |
| Post subject: | |
The 83+ pound crank is not that common, most of the forged steel cranks are the 76 pound version. Some racers know the advantage of that lighter cast crank and use it...  I seen cast crank SL6 engine's make 300 HP and stay together. I have also seen broken SL6 cranks, both cast and forged steel. I guess it comes down to what you have available and what to build-up but no one should argue the fact that a lighter crank engine is going to spin-up faster and potentially carry higher RPMs. DD |
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