Crank turning question

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dartfreak75

dartfreak75

Restore it, Dont part it!
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On a budget build how bad do the journals have to be to let them go and not turn them? I am kind of on the fence I called the machinist and got a quote but im not sure if its really needed and if Its not a necessity id like to save the 150 bucks lol.here are some pics of the journals. Im thinking alot of the bad spots will polish out.

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Can you catch a fingernail on them? I use fine #600 paper with a leather string wrapped around it. Some start w #400 and then go to #600. If the clearance is too much you might need .001" under bearings on one half.
 
Those should polish out but you need to mic them and see what you got, I have polished .0005 just to get more oil clearance and you need to mic after to be sure its round and no taper
 
Demonic said:
Can you catch a fingernail on them? I use fine #600 paper with a leather string wrapped around it. Some start w #400 and then go to #600. If the clearance is too much you might need .001" under bearings on one half.
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There is one journal that i can feel a groove with my nail. I will try and polish it and see what it looks like.
 
more to it than if you can hang a fingernail on it!! take it to your machinist and let him mic it and tell you if it needs turned or not! i wouldn't sweat 150 bucks on the basic foundation of your engine!
 
Those really don't look very bad at all. If they measure good with a micrometer (not a caliper), then I would lightly polish and use for budget use. I would not worry if some scratches were still there after a light polish. I'd spend money on getting good bores before sweating on this crank.
 
nm9stheham said:
Those really don't look very bad at all. If they measure good with a micrometer (not a caliper), then I would lightly polish and use for budget use. I would not worry if some scratches were still there after a light polish. I'd spend money on getting good bores before sweating on this crank.
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Thats kinda what I was thinking to there is one spot you can see in the pic i bumped the connecting rod stud into the journal and left a scratch that was my biggest concern.
I dont have a good micrometer. I may take it to him when i take the block and have him check it just in case.
 
I wouldn't run that. Turn/polish. The $150 will be less than taking apart again if something goes wrong.
 
I have taken many cranks to the machine shop and every single time the machinist said they needed to be turned. Weather they were out of round or the journals were tapered. I once took a brand new Ed Hamburger crank to be polished just to get alittle more bearing clearance. When I came back to pick it up they had turned the crank undersize. I said wtf, he said it was out of spec. Kinda makes me wonder. Kim. I should state that it was a few different machine shops over the years.
 
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oldkimmer said:
I have taken many cranks to the machine shop and every single time the machinist said they needed to be turned. Weather they were out of round or the journals were tapered. I once took a brand new Ed Hamburger crank to be polished just to get alittle more bearing clearance. When I came back to pick it up they had turned the crank undersize. I said wtf, he said it was out of spec. Kinda makes me wonder. Kim
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if you don't trust you machine man, take it to an engine builder that knows his stuff and uses a quality mic! there's more to a journal than meets the eye, i don't have the vocabulary to explain it! if you want your motor to live a long life get it mic'ed by somebody you trust unless you, your self is a machinest!!
 
Out of the bag, what I see is a crank that may have been worked on previously. Factory oil hole chamfers aren't that big, has it been polished previously, is it under size already? Look on the back side of the bearing shell and see if there's any undersize #'s. It needs to be measured to give you a proper answer. If it is still "standard", the limited info from just the pictures indicate .001 thou unders could clean it up.
 
The problem with engine machinist is they only make $ if they machine things.
 
guess im lucky, fully trust my crank man! got 3 other very reputable machinest/builders i trust just as much! and all 4 rather not do a darn thing...lol
 
oldkimmer said:
I have taken many cranks to the machine shop and every single time the machinist said they needed to be turned. Weather they were out of round or the journals were tapered. I once took a brand new Ed Hamburger crank to be polished just to get alittle more bearing clearance. When I came back to pick it up they had turned the crank undersize. I said wtf, he said it was out of spec. Kinda makes me wonder. Kim. I should state that it was a few different machine shops over the years.
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That is kinda what I was thinking also lol
Max1196 said:
Out of the bag, what I see is a crank that may have been worked on previously. Factory oil hole chamfers aren't that big, has it been polished previously, is it under size already? Look on the back side of the bearing shell and see if there's any undersize #'s. It needs to be measured to give you a proper answer. If it is still "standard", the limited info from just the pictures indicate .001 thou unders could clean it up.
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This engine has never been apart I pulled it from a one owner car that had 80k miles (or 180k) but it was the original owner it was an older lady she had wrecked it and broke the control arm and parked it. Bought the whole car for 500 pulled the engine and transmission and sold the car for scrap. And the bearing are standard size.
 
brian6pac said:
The problem with engine machinist is they only make $ if they machine things.
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Exactly why im asking you guys! Because I dont know enough to make that decision and I know no matter what he is gonna want to turn it lol that 150 bucks in his pocket.
 
I consider the crankshaft one area I do not cut corners on. Catching a thumbnail on that center strip really tells you nothing. Sure, if you can catch it good, there's some wear. But can your thumbnail tell if the journal is out of round? If the radius is out of spec? If you're replacing bearings too, you will be money ahead to simply put a crank kit in it. Crank bearings and all. While the machinist may charge you 150, you can get a complete crank kit bearings and all for "around" 200 dollars.
 
RustyRatRod said:
I consider the crankshaft one area I do not cut corners on. Catching a thumbnail on that center strip really tells you nothing. Sure, if you can catch it good, there's some wear. But can your thumbnail tell if the journal is out of round? If the radius is out of spec? If you're replacing bearings too, you will be money ahead to simply put a crank kit in it. Crank bearings and all. While the machinist may charge you 150, you can get a complete crank kit bearings and all for "around" 200 dollars.
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https://www.oreillyauto.com/detail/...-kit/13490/4175730/1975/plymouth/duster?pos=0
169 bucks hard to beat!!
 
RustyRatRod said:
I consider the crankshaft one area I do not cut corners on. Catching a thumbnail on that center strip really tells you nothing. Sure, if you can catch it good, there's some wear. But can your thumbnail tell if the journal is out of round? If the radius is out of spec? If you're replacing bearings too, you will be money ahead to simply put a crank kit in it. Crank bearings and all. While the machinist may charge you 150, you can get a complete crank kit bearings and all for "around" 200 dollars.
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It has been in my plans to replace all the bearing crank and rod! I was gonna just use standard bearings and plastigauge them. But then found the groove spots and was considered.
 
Ok so I looked at the new (refurbished) cranks and they have one for standard transmission and one for automatic. I know there is a difference in the bushings dia between the two and im kinda back and forth on doing a manual swap. So if I get the manual crank can I still use it with an automatic if I decide not to do the manual swap or if I use the auto until I can afford the manual? Or is the flywheel area cut differently?
 
Another question wouldn't the new crank change my balance? Im using same weight pistons and not internally balancing it.
 
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