max turning a crank?

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max turning a crank?

Post  torino501 on July 10th 2013, 10:36 am

i see under size bearings all the way down to .060 .do you guys feel comfortable cutting one down that far on rods and mains for street/strip/race...?weather for a standard crank or a stroker...?

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Re: max turning a crank?

Post  dfree383 on July 10th 2013, 10:41 am

IMO its not an issue.
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Re: max turning a crank?

Post  the Coug on July 10th 2013, 1:34 pm

no Issue
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Re: max turning a crank?

Post  torino501 on July 10th 2013, 2:53 pm

thanks homies...

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Re: max turning a crank?

Post  bbf-falcon on July 10th 2013, 6:15 pm

I agree,i've personally never used one over .030,but wouldn't be afraid to go further if need be.

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Re: max turning a crank?

Post  the Coug on July 10th 2013, 6:27 pm

Remember the old strokers were 460 cranks offset ground and turned to chevy or Band Aid journals I ran a 4 inch stroker for many years....
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Re: max turning a crank?

Post  Lem Evans on July 10th 2013, 8:01 pm


The decision should be driven by bearing availability i.m.o.

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Re: max turning a crank?

Post  IDT-572 on July 10th 2013, 10:37 pm

the Coug wrote:Remember the old strokers were 460 cranks offset ground and turned to chevy or Band Aid journals I ran a 4 inch stroker for many years....

The strength of the crank is not the problem, it's the thickness of the bearing. Does the steel backing get thicker or the babbit material. If the steel backing gets thicker would that change the crush? and if the babbit is thicker will it hold up.

I'm sure the manufactures have all this worked out, but I wouldn't run one at .060 unless it was my only option.
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Re: max turning a crank?

Post  Paul Kane on July 10th 2013, 11:16 pm

torino501 wrote:i see under size bearings all the way down to .060 .do you guys feel comfortable cutting one down that far on rods and mains for street/strip/race...?weather for a standard crank or a stroker...?
In the proper engine build applications and in good tune, an OEM cast 460 crankshaft turned 0.060"/0.060" could conceivably be utilized in an engine generating more than 1000 hp.  The same is true with forged steel stroker crankshafts, and the cast stroker crankshafts should be considered suitable for the power handling relative to their manufacturer"s power "rating" regardless of dimensional undersize.

I always found it perplexing when others ask it 0.060" undersize is acceptable on an OEM crankshaft when they are regularly offset stroked to 0.300" undersize (5 times that 0.060" amount) without issue....and have been run as such successfully for decades.

One important thing to consider when grinding a crankshaft undersize is that the wide fillet radi of the journals are not compromised. Doing so can do more to weaken the strucural integrity of a crankshaft (in a high horsepower application) than any undersize dimensions properly ground for any undersize bearings available today.

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Re: max turning a crank?

Post  LivermoreDave on July 12th 2013, 9:13 am

There is a post on the site somewhere with pictures of Blake's aftermarket crankshaft that occurred damage during a dyno run. Adney displayed a measuring technique that demonstrated the crankshaft's weakness. Point being, make sure the material is there to adequately support your application before removing any material. Maybe a rare occurrence, although the assuring of dimensions should be a practice of every engine's assembly.

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Re: max turning a crank?

Post  IDT-572 on July 12th 2013, 9:18 am

LivermoreDave wrote:There is a post on the site somewhere with pictures of Blake's aftermarket crankshaft that occurred damage during a dyno run. Adney displayed a measuring technique that demonstrated the crankshaft's weakness. Point being, make sure the material is there to adequately support your application before removing any material. Maybe a rare occurrence, although the assuring of dimensions should be a practice of every engine's assembly.

Dave.

That is right Dave, if that crank had been turned .060 on the rod pin there would have only been about .060 left above the lightning hole.

Generally on most cranks .060 is not a problem, but you dang better well check what your turning.

Thanks Dave.............
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Re: max turning a crank?

Post  LivermoreDave on July 12th 2013, 9:20 am

Good morning Blake. Wish your well.

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Re: max turning a crank?

Post  IDT-572 on July 12th 2013, 9:21 am

Thanks bud same to you..............Cool 
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Re: max turning a crank?

Post  Lem Evans on July 12th 2013, 7:29 pm

Lem Evans wrote:
The decision should be driven by bearing availability i.m.o.
 
Seems everybody is 'comfortable' turning a crankshaft .060" under. So, who makes a -.060" main bearing for the bbf? If it is available, is it a race grade bearing?

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Re: max turning a crank?

Post  torino501 on July 13th 2013, 9:18 am

I think I saw a king bearing in summit at .060 stock,street race I don't remember

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Re: max turning a crank?

Post  torino501 on July 13th 2013, 9:21 am

at .040 there is clevite and king, at .030 there is sealed power,clevite,and king...

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Re: max turning a crank?

Post  Paul Kane on July 13th 2013, 10:16 am

IDT-572 wrote:
LivermoreDave wrote:There is a post on the site somewhere with pictures of Blake's aftermarket crankshaft that occurred damage during a dyno run. Adney displayed a measuring technique that demonstrated the crankshaft's weakness. .....

Dave.

That is right Dave, if that crank had been turned .060 on the rod pin there would have only been about .060 left above the lightning hole.

Generally on most cranks .060 is not a problem, but you dang better well check what your turning.

Thanks Dave.............  
Holy crap this sounds like a piss-poor design...or a mis-located lightening hole(s).  Either way, if a rod throw really had just 0.060" ID wall thickness all the way through/across the journal OD, then that journal @ std 2.200" (ie, .090" wall) would have virtually no better structural integrity turned undersize or not.  (I realize the lightening hole was probably not parallel to the journal OD.)  I'll bet this was an offshore crankshaft being discussed--I have spent some time working directly with "offshore engineers" and was shocked at just how things are copied and how little is researched...and how much is overlooked and/or missed due to the lack of understanding many of the speicific nuances and details of what they intend to manufacture. Shocked 

Paul


Last edited by Paul Kane on July 13th 2013, 10:34 am; edited 1 time in total
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Re: max turning a crank?

Post  Paul Kane on July 13th 2013, 10:24 am

Lem Evans wrote: 
Seems everybody is 'comfortable' turning a crankshaft .060" under. So, who makes a -.060" main bearing for the bbf? If it is available, is it a race grade bearing?
The word "race" on the side of the bearing box does not a race bearing make. Wink 

Nor does necesssarily its construction. By that, I mean that a hard steel-backed "race" bearing with a micro-thin babbit layer is not always the preferred, go-to engine bearing for a high performance engine build. Sometimes the very thick babbit bearing is the builder's choice, and with good reason. It depends on the engine program, application, etc. So yeah, 0.060" bearings are available for big hp engines, just not in every manner of bearing costruction as can be found in lesser undersizes. Cool 

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Re: max turning a crank?

Post  IDT-572 on July 14th 2013, 12:59 am

Paul Kane wrote:
IDT-572 wrote:
LivermoreDave wrote:There is a post on the site somewhere with pictures of Blake's aftermarket crankshaft that occurred damage during a dyno run. Adney displayed a measuring technique that demonstrated the crankshaft's weakness. .....

Dave.

That is right Dave, if that crank had been turned .060 on the rod pin there would have only been about .060 left above the lightning hole.

Generally on most cranks .060 is not a problem, but you dang better well check what your turning.

Thanks Dave.............  
Holy crap this sounds like a piss-poor design...or a mis-located lightening hole(s).  Either way, if a rod throw really had just 0.060" ID wall thickness all the way through/across the journal OD, then that journal @ std 2.200" (ie, .090" wall) would have virtually no better structural integrity turned undersize or not.  (I realize the lightening hole was probably not parallel to the journal OD.)  I'll bet this was an offshore crankshaft being discussed--I have spent some time working directly with "offshore engineers" and was shocked at just how things are copied and how little is researched...and how much is overlooked and/or missed due to the lack of understanding many of the speicific nuances and details of what they intend to manufacture. Shocked 

Paul

Paul,

It was an Eagle cast steel 4.500 stroke crank. I talked to the guy I deal with at Eagle and it fell on deaf ears. The lightning hole was very large and the top of the pin flattened above the lightning hole.

The oil hole was almost parallel with the crank pin................ Bad design all around. I know it helps with the balancing but it sure takes away from the strength of the piece
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Re: max turning a crank?

Post  Paul Kane on July 15th 2013, 11:22 am

IDT-572 wrote:
Paul Kane wrote:
IDT-572 wrote:
LivermoreDave wrote:There is a post on the site somewhere with pictures of Blake's aftermarket crankshaft that occurred damage during a dyno run. Adney displayed a measuring technique that demonstrated the crankshaft's weakness. .....

Dave.

That is right Dave, if that crank had been turned .060 on the rod pin there would have only been about .060 left above the lightning hole.

Generally on most cranks .060 is not a problem, but you dang better well check what your turning.

Thanks Dave.............  
Holy crap this sounds like a piss-poor design...or a mis-located lightening hole(s).  Either way, if a rod throw really had just 0.060" ID wall thickness all the way through/across the journal OD, then that journal @ std 2.200" (ie, .090" wall) would have virtually no better structural integrity turned undersize or not.  (I realize the lightening hole was probably not parallel to the journal OD.)  I'll bet this was an offshore crankshaft being discussed--I have spent some time working directly with "offshore engineers" and was shocked at just how things are copied and how little is researched...and how much is overlooked and/or missed due to the lack of understanding many of the speicific nuances and details of what they intend to manufacture. Shocked 

Paul

Paul,

      It was an Eagle cast steel 4.500 stroke crank. I talked to the guy I deal with at Eagle and it fell on deaf ears. The lightning hole was very large and the top of the pin flattened above the lightning hole.

The oil hole was almost parallel with the crank pin................  Bad design all around. I know it helps with the balancing but it sure takes away from the strength of the piece  
"Pin flattened above the lightening hole?" Do you mean that the wall thickness was so thin and material so soft/maleable that the journal OD flattened????? That is completely unnacceptable as the component might be considered not fit for its intended application.

The United States has a Federal "fit for use" law which specifies that anything offered for sale has an "implied warranty of merchantability," which means the "goods sold will do what they are supposed to do."  A crankshaft should not flatten due to material quality and poor design and manufacturing.  I would think the manufacturer's only loop-hole in your particular situation would be if you were using the crankshaft beyond the hp rating offered by the manufacturer. (And I'll bet that you were, lol. Very Happy  ) But...a crankshaft with material this soft and poorly manufactured (<-----crank pin's hole size and location) might be reason enough to claim implied warranty under the federal fit for use act. It might not be worth the legal battle, but it can at least be reported.

Paul
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Re: max turning a crank?

Post  IDT-572 on July 15th 2013, 12:01 pm

Paul Kane wrote:
IDT-572 wrote:
Paul Kane wrote:
IDT-572 wrote:
LivermoreDave wrote:There is a post on the site somewhere with pictures of Blake's aftermarket crankshaft that occurred damage during a dyno run. Adney displayed a measuring technique that demonstrated the crankshaft's weakness. .....

Dave.

That is right Dave, if that crank had been turned .060 on the rod pin there would have only been about .060 left above the lightning hole.

Generally on most cranks .060 is not a problem, but you dang better well check what your turning.

Thanks Dave.............  
Holy crap this sounds like a piss-poor design...or a mis-located lightening hole(s).  Either way, if a rod throw really had just 0.060" ID wall thickness all the way through/across the journal OD, then that journal @ std 2.200" (ie, .090" wall) would have virtually no better structural integrity turned undersize or not.  (I realize the lightening hole was probably not parallel to the journal OD.)  I'll bet this was an offshore crankshaft being discussed--I have spent some time working directly with "offshore engineers" and was shocked at just how things are copied and how little is researched...and how much is overlooked and/or missed due to the lack of understanding many of the speicific nuances and details of what they intend to manufacture. Shocked 

Paul

Paul,

      It was an Eagle cast steel 4.500 stroke crank. I talked to the guy I deal with at Eagle and it fell on deaf ears. The lightning hole was very large and the top of the pin flattened above the lightning hole.

The oil hole was almost parallel with the crank pin................  Bad design all around. I know it helps with the balancing but it sure takes away from the strength of the piece  
"Pin flattened above the lightening hole?" Do you mean that the wall thickness was so thin and material so soft/maleable that the journal OD flattened????? That is completely unnacceptable as the component might be considered not fit for its intended application.

The United States has a Federal "fit for use" law which specifies that anything offered for sale has an "implied warranty or merchantability," which means the "goods sold will do what they are supposed to do."  A crankshaft sholuld not flatten due to material quality and poor design and manufacturing.  I would think the manufacturer's only loop-hole in your particular situation would be if you were using the crankshaft beyond the hp rating offered by the manufacturer. (And I'll bet that you were, lol. Very Happy  ) But...a crankshaft with material this soft and poorly manufactured (<-----crank pin's hole size and location) might be reason engouh to claim warranty under the federal fit for use act. It might not be worth the legal battle, but it can still be reported.
Paul

I "was" using this crank beyond it's rated HP, but, with the pin being that close to the surface of the rod journal, grinding that crank .060 on the rods would weaken it even more. One other thing, the lightning hole diameter was a ton bigger on this crank also, which makes a bigger area to weaken.


Bottom line is, you need to look at every application before putting a blanket statement on turning cranks.

And this was not pointed at you, I understand where you are coming from.
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Re: max turning a crank?

Post  Paul Kane on July 15th 2013, 9:18 pm

IDT-572 wrote:
Paul Kane wrote:
IDT-572 wrote:
Paul Kane wrote:
IDT-572 wrote:
LivermoreDave wrote:There is a post on the site somewhere with pictures of Blake's aftermarket crankshaft that occurred damage during a dyno run. Adney displayed a measuring technique that demonstrated the crankshaft's weakness. .....

Dave.

That is right Dave, if that crank had been turned .060 on the rod pin there would have only been about .060 left above the lightning hole.

Generally on most cranks .060 is not a problem, but you dang better well check what your turning.

Thanks Dave.............  
Holy crap this sounds like a piss-poor design...or a mis-located lightening hole(s).  Either way, if a rod throw really had just 0.060" ID wall thickness all the way through/across the journal OD, then that journal @ std 2.200" (ie, .090" wall) would have virtually no better structural integrity turned undersize or not.  (I realize the lightening hole was probably not parallel to the journal OD.)  I'll bet this was an offshore crankshaft being discussed--I have spent some time working directly with "offshore engineers" and was shocked at just how things are copied and how little is researched...and how much is overlooked and/or missed due to the lack of understanding many of the speicific nuances and details of what they intend to manufacture. Shocked

Paul

Paul,

     It was an Eagle cast steel 4.500 stroke crank. I talked to the guy I deal with at Eagle and it fell on deaf ears. The lightning hole was very large and the top of the pin flattened above the lightning hole.

The oil hole was almost parallel with the crank pin................  Bad design all around. I know it helps with the balancing but it sure takes away from the strength of the piece  
"Pin flattened above the lightening hole?" Do you mean that the wall thickness was so thin and material so soft/maleable that the journal OD flattened????? That is completely unnacceptable as the component might be considered not fit for its intended application.

The United States has a Federal "fit for use" law which specifies that anything offered for sale has an "implied warranty or merchantability," which means the "goods sold will do what they are supposed to do."  A crankshaft sholuld not flatten due to material quality and poor design and manufacturing.  I would think the manufacturer's only loop-hole in your particular situation would be if you were using the crankshaft beyond the hp rating offered by the manufacturer. (And I'll bet that you were, lol. Very Happy ) But...a crankshaft with material this soft and poorly manufactured (<-----crank pin's hole size and location) might be reason engouh to claim warranty under the federal fit for use act. It might not be worth the legal battle, but it can still be reported.
Paul

I "was" using this crank beyond it's rated HP, but, with the pin being that close to the surface of the rod journal, grinding that crank .060 on the rods would weaken it even more. One other thing, the lightning hole diameter was a ton bigger on this crank also, which makes a bigger area to weaken.


Bottom line is, you need to look at every application before putting a blanket statement on turning cranks.

And this was not pointed at you, I understand where you are coming from.    
No offense taken.  There are several key points here, one being that 0.060" undersize (which is only a 0.030" turn all the way around the journal) ought not affect crankshaft power handling capabilities in most any properly manufactured (and properly rated) crankshaft.  If it did, then it is not likely that such bearing undersizes would be readily available for the masses. What I stated earlier in this thread specifically was, "In the proper engine build applications and in good tune, an OEM cast 460 crankshaft turned 0.060"/0.060" could conceivably be utilized in an engine generating more than 1000 hp.  The same is true with forged steel stroker crankshafts, and the cast stroker crankshafts should be considered suitable for the power handling relative to their manufacturer"s power "rating" regardless of dimensional undersize."  I think you said you went past the manufacturer's power rating of the crankshaft you used.

And your point about making blanket statements is noteworthy because they are made all the time on these forums, but unfortuntalely they can be interpreted by some readers as a "steadfast rule" and regardless of any other factors (such as the condition of the actual component in question) that might need to be considered.

Having said that, the fact that one can actually buy a crankshaft which is incapable of enduring abuse relative to such miniscule bearing undersizes is outrageous (presuming this is how they are engineered), let alone that even at std-std it probably wouldn't hold up any better. I do still feel such a crankshaft is either a major blem or a major engineering oversight by the manufacturer, and in either case you deserve your money back (unless you were a couple hundred hp beyond the manufacturer's rating).  On the other hand, if the crankshaft can handle the max available bearing undersizes and still endure its maximum power rating as specified by the manufacturer, then there's really nothing wrong with it technically speaking and they can claim that it failed because you subjected it to more power than was rated (waranteed).

By the way, federal fit for use has a statute of limitations period of 4 years, in case you still have time and/or care to call the company again. As for me, if I had such crankshaft trouble (within its power rating) and concluded that such obviously unacceptable dimensions were clearly the culprit I might never have let the manufacturer/merchant get away with it. Grrrr.

Paul
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Re: max turning a crank?

Post  IDT-572 on July 16th 2013, 11:07 am

It was in my TFS headed 557, and it was making a good bit more than the rated HP. I, at that time, and since have seen Scat 9000 series cranks handle more than rated hp (good bit more). I had it in the shop and decided, bad decision........... to use it.

It seemed to start flexing at somewhere around 700 hp on the dyno. As we changed jets and timing to expect a hp increase all I was seeing was oil temp increase at a higher than normal rate and oil pressure acting odd but, not anything alarming. I decided to pull it off the dyno and take a look.

There are pictures of it on here somewhere. (Winter tech seminar) Adney Brown actually witnessed the dyno session and after I told him what crank I was running told us what journals on the crank would be in trouble. When we got into it the crank was just like he said it would be.

You pick, easier to balance or stronger crank.
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Re: max turning a crank?

Post  Lem Evans on July 17th 2013, 8:09 pm

Paul Kane wrote:
Lem Evans wrote: 
Seems everybody is 'comfortable' turning a crankshaft .060" under. So, who makes a -.060" main bearing for the bbf? If it is available, is it a race grade bearing?
The word "race" on the side of the bearing box does not a race bearing make. Wink 

Nor does necesssarily its construction. By that, I mean that a hard steel-backed "race" bearing with a micro-thin babbit layer is not always the preferred, go-to engine bearing for a high performance engine build. Sometimes the very thick babbit bearing is the builder's choice, and with good reason. It depends on the engine program, application, etc. So yeah, 0.060" bearings are available for big hp engines, just not in every manner of bearing costruction as can be found in lesser undersizes. Cool 

Paul

One may do what they what to but, aint no way I'm gonna put a station wagon bearing in a racing engine.



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Re: max turning a crank?

Post  torino501 on July 17th 2013, 10:20 pm

I had ordered a scat rotating assy for my big bore frpp351 block.427 scat 4340 and h-beams. why in the hell would they put an clevite h bearing in thier kit....? I up graded to the p bearings.

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