Turning down stroker crank

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MidTexCuda

MidTexCuda

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Apparently I have a RB stroker crank that cant be sold because of the fact it is a Chinese unit finished here in in Texas. I has handled over 650HP with no issue so I am wondering if anyone has cut a 4.15 aftermarket crank down to go in a B block and cut the rods down to BBC. I would get it re nitride.
Is this a cost effective option?
Will the main issue be the rod width difference?
 
Depends on availability of quality crank grinders in your area. You can have the rod journals offset ground for 4.250 or 4.300 stroke w/2.200 BBC rods. The mains can be ground for 2.625 B block dimensions as well.

It will be less than buying a new crank. S/F....Ken M
 
Where the oil passages end up on the rod journel can be a problem also.
 
It could probably be done but I can't believe with hardening it would be under $300. Are the counterweights being cut down too? You'll still have an issue with side clearance but a lot of times that's just ignored anyway. Depending on the quality of the crank - you might be getting thin between the oil holes and the drilled throws.
Knowing you're power habits through your posting - I'd get the right crank and use that one for it's intended purpose.
 
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Typically (and Craftsman tools, especially the box end wrenches are a great example of this), the Chinese products rely on extra material to make up for material strength deficiencies. I couldn't provide my own photos as I refuse to buy the Chinesium stuff but the 'net provides some photos.

Your crank could be a top notch piece, or it could be a top-notch POS, and only your materials analyst knows for sure...but given the nature of what you're doing, both in application and in modification, I can't say this is one of those Good Ideas.

Can't sell it? That's the cost of buying Chinese stuff, because nobody knows if it's CCT (Cheap Chinese Trash) or not, and you paid your price and (hopefully) saved your money on it. Someone else has to save money in lockstep to take that risk.

You might be removing material that the crank really needs to hold together...Leave it on the auction block. Or mount a mailbox to it. Or build a motor around it and sell it that way, if your conscience lets you.

It's only a cost-effective option if your motor doesn't grenade.
 
MidTexCuda said:
Apparently I have a RB stroker crank that cant be sold because of the fact it is a Chinese unit finished here in in Texas. I has handled over 650HP with no issue so I am wondering if anyone has cut a 4.15 aftermarket crank down to go in a B block and cut the rods down to BBC. I would get it re nitride.
Is this a cost effective option?
Will the main issue be the rod width difference?
Click to expand...

Turning down the counterweights and grinding the mains so you can use it in a B block might be cost effective. Offset grinding the rod journals is probably not a good idea.

New cranks are fairly inexpensive these days so if you need a different crankshaft just buy a new one. Molnar has fair priced Mopar cranks, SCAT is another vendor with a good selection of cranks.
 
Thanks for all of the input. I have been shopping and reading about my crank options for over a year. I know the "Chinese" vs. "US" crank debate. I realize that until you pony up to at least the 1800.00 mark your still buying a overseas foundered crank with a wide margin for hardness. I know that 450 to 850 will get you a China forged and finished crank, and that 850 to 1800 will get you a China forged crank finished here in the states (most of the time) I was just curious if there would be a huge issue with turning mine down. I know I will most likely need a crank like a Dragonslyer but if my crank could be turned down at a good price and survive up to 1k it may be an option for me. I have scoured the web and almost every forum I can find and it seems that the China cranks have lived in high HP machines and that the failures have been mostly because of poor machine work, rod failures, and other related issues. I struggled to find many if any post about a crank breaking due to poor metal. I could be wrong. I have no plan to spin this motor past 6500 and will be putting my money in the rods.
 
AndyF said:
Turning down the counterweights and grinding the mains so you can use it in a B block might be cost effective. Offset grinding the rod journals is probably not a good idea.

New cranks are fairly inexpensive these days so if you need a different crankshaft just buy a new one. Molnar has fair priced Mopar cranks, SCAT is another vendor with a good selection of cranks.
Click to expand...

I think he wants to stay away from Chinese forgings.....
 
No im fine with running a China crank. Just wanted to know if i could turn my 4340 4.15 rb crank down with no issues for half the cost of one of the scat, eagle, RPM, molinar, K1, 440 scource ect. cranks because odds are good that my crank came from the same foundry.
 
No thanks...

(I just turned down a BB stroker crank...)
 
turn down the mains for the 400 block no problem, many times that been done, with a steel crank and no rehardening-ok cuz a layer of oil when running. I would forget about the chevy rods-they are narrower and you do not need to offset grind for more stroke, or does anyone make steel rods with the smaller big end in the mopar width? years ago we got some aluminum rods someone was making in limited batches
 
Yes, Molnar makes Mopar rods that are Mopar width but 2.200 journal. So you can use those rods on a Mopar crank that has been offset ground to a BBC journal size.
 
EchoSixMike said:
Depends on availability of quality crank grinders in your area. You can have the rod journals offset ground for 4.250 or 4.300 stroke w/2.200 BBC rods. The mains can be ground for 2.625 B block dimensions as well.

It will be less than buying a new crank. S/F....Ken M
Click to expand...

i have heard this, so what defines a good crank grinder vrs everyday dude. got a stroker old school welded up crank that spun #7 and needs turned. was told by my builder its going to be tough to find someone who knows what they doing. special equipment? all in the skill of operator?
 
mopar505 said:
i have heard this, so what defines a good crank grinder vrs everyday dude. got a stroker old school welded up crank that spun #7 and needs turned. was told by my builder its going to be tough to find someone who knows what they doing. special equipment? all in the skill of operator?
Click to expand...

Skill of the operator....I have watched 100's of cranks being ground.....
 
mopar505 said:
i have heard this, so what defines a good crank grinder vrs everyday dude. got a stroker old school welded up crank that spun #7 and needs turned. was told by my builder its going to be tough to find someone who knows what they doing. special equipment? all in the skill of operator?
Click to expand...

Skill and attention to detail IMO. It's the reason you see all these made in China cranks that are finished in America. Too many junked cranks sent back to China, so they finish 'em here. I'm OK with it, let them poison their country and we do the skilled work. S/F.....Ken M
 
I don't know if this will help or not but on my 572, we used an old Mopar/Kellogs billet crank. It had Mopar rod journals and we sent the crank to Marine Crankshaft in California. They turned the journals to a chevy 2.2" and re nitrided the crank. It was about $1,000 all said and done.
 
I just talked to my engine building friend. Don't know if its true or not but he said SCAT and Eagle cranks are made from Argentina steel and possible made there. He said thinks the are hard as hell and the eagle unit may even balance better.
He also told me the cost to get mine fixed up would be to high.
 
around here they(the 3 of the 14 shops I contacted that would even take the work) all wanted between $600-800 to turn a 440 crank to fit a 383 block, that was without any hardening or balancing included, and they were even reluctant to say they would do it because they wanted me to just buy an aftermarket crank at that price point.
 
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