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| Is this a cast crank or forged? https://slantsix.org/forum/viewtopic.php?t=55846 |
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| Author: | Feather_Duster [ Thu Jul 24, 2014 5:16 pm ] |
| Post subject: | Is this a cast crank or forged? |
Looks like cast to me, but what do I know? I can't find any part numbers on it. See album below. The last picture is the only numbers I can find on the block. https://picasaweb.google.com/1073503068 ... directlink |
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| Author: | moparmatt441 [ Thu Jul 24, 2014 5:32 pm ] |
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looks to be cast, the thin parting line tells us it was cast. |
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| Author: | CNC-Dude [ Thu Jul 24, 2014 6:58 pm ] |
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There should also be a forging or casting number on the counterweights somewhere to verify. You can measure how wide the thrust face is, they are wider on a cast crank than on a forged crank also. |
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| Author: | Feather_Duster [ Thu Jul 24, 2014 8:52 pm ] |
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Thanks for the input. Does anyone think otherwise? I don't want to order the wrong bearings. CNC-Dude -The only markings on the crank is an "R" stamped in the counterweight (looks like a balance marking), a "5" that appears to be cast in, and a "B" or "8" that appears to be cast in. The "5" and "B" can be seen well in the 6th photo in the album. Are you saying to measure the green line in this photo? 
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| Author: | CNC-Dude [ Thu Jul 24, 2014 9:21 pm ] |
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Yes, from the face that green line is on to the opposite side. That close-up of the grainy metal texture of the crank really appears to me to be steel. |
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| Author: | Feather_Duster [ Thu Jul 24, 2014 10:24 pm ] |
| Post subject: | |
Ok, measuring from the green line face to the opposite face (see red line below), I am getting ~1.261". And to clarify, I am measuring this width at main #3, correct?  
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| Author: | slantzilla [ Thu Jul 24, 2014 11:14 pm ] |
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If the rod journals are about 1" it is cast. 1.25 ish is steel. Just from the pics that looks to me to be a steel crank. |
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| Author: | CNC-Dude [ Thu Jul 24, 2014 11:15 pm ] |
| Post subject: | |
Sorry, I had it backward(going from memory). The forged crank has the wider thrust flange at approx. 1.254", while the cast crank has one approx. 1.105". So you have a forged crank. |
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| Author: | Feather_Duster [ Fri Jul 25, 2014 7:33 pm ] |
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Measuring the rod journals the same way, I get about 1.226". So it would seem I have a forged crankshaft. Thanks for the help. |
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| Author: | moparmatt441 [ Sat Jul 26, 2014 7:21 am ] |
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Many engines were produced with both forged-steel and cast cranks over their production lives. It's surprising how many of us have a hard time telling a forged crank from a cast crank while looking right at them. It's easy to tell them apart, if you know what to look for. Here are some quick clues: The casting process results in greater control of the net shape in the forming process, which is evident from visual clues in the finished crankshaft. Looking at the counterweights is a dead giveaway. A forged crank's counterweights will generally have a rougher look with rounded edges, while a cast crank by comparison will show sharp, well-defined edges. A second visual check can be made by viewing the parting line that defines where the casting core or forging dies separated. A cast crank will have a thin, sharp, and straight parting line, while the parting line on a forging will be wide and generally less defined. For the visually challenged, a forged crank can be identified by ear. A forging will ring like a bell when tapped on the counterweight with a steel hammer, while a casting will give a dull thud. |
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| Author: | moparmatt441 [ Sat Jul 26, 2014 7:24 am ] |
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Picture number 5 looks like a thin parting lines, this is what led me to believe it was cast. |
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| Author: | Feather_Duster [ Sat Jul 26, 2014 9:31 am ] |
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I would not have thought that a forged crank would LOOK cast -- rough texture, parting lines, etc. But I guess they do. The parting line in that concave section in pic #5 measures about 0.100-0.125" wide... not sure if that is considered thin or not. But the counterweight definitely rings. A light tap with a hammer and I can hear it ring for about 6 seconds before it dies out. |
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| Author: | moparmatt441 [ Sat Jul 26, 2014 10:19 am ] |
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Quote: I would not have thought that a forged crank would LOOK cast -- rough texture, parting lines, etc. But I guess they do.
Must be forged, the pics threw me off.
The parting line in that concave section in pic #5 measures about 0.100-0.125" wide... not sure if that is considered thin or not. But the counterweight definitely rings. A light tap with a hammer and I can hear it ring for about 6 seconds before it dies out. |
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| Author: | CNC-Dude [ Sat Jul 26, 2014 3:27 pm ] |
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The last few pics of the close ups of the journal were a dead giveaway for me. The ones posted previously didn't reveal the metal texture that well and I also had difficulty seeing the parting line that well and was on the fence. But the close up pics gave it away, plus the thrust width verified it. The forged crank is also about 20 pounds heavier for than the cast crank which weighs about 68 pounds. |
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