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6223 crankshaft question for my 1967 L78 build

L78fanatic

Well-Known Member
Senior Member
I am considering buying a 6223 crankshaft, and it has been magged with polished journals. The journals have never been cut. However it is 001 001 on the journals. It came that way from the factory I understand. Was that common back in the day? It means the bearings would have to be .001/.001 thinner, and I didn't realize they made crank bearings to any thickness needed. I need a little education on this as I'm not familiar with this at all. He says it's bagged up and ready for installation. It might be a nice crank....and I have bought from the guy before, but I am just not sure.

Thanks for any advice on this.

John
 
Just to update, I am not certain whether or not the stock uncut journals are .001 "over" or "under" as of yet. But, either way the question is the same: can bearings be bought that are either .001" thicker than stock or .001" thinner than stock width?
 
I'm not going to be much help here, but I'd run that by my machinist. 2.5 on the mains and 2.0 on the rods is what I'm familiar with, or 1 thou per inch. I know bearings have a plus, which is a bit looser, but never heard of shelf items being tighter. Never heard of a factory crank being 1 thou smaller?????
 
I’m still researching but I tend to agree with you that the journals are likely .001 oversize thus need bearings .001” under stock size. (EDIT) Or, come to think of it, undersize would make more sense, as back in the day without computers when the machinist turned the journals it might have been very easy to be off 0.001" by over cutting & polishing. I've posed the question to the seller...will let you know when I hear back.
 
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The crank journals are .001" over spec diameter, so the bearings need to be .001" undersized for both the main & rod journals. If anyone has a good source where I can buy the bearings, let me know. Thx!
 
I can't seem to get the answers I need from the seller. This guy sells Chevy parts all the time (well known seller on the Yenko forum), and I expected more from him. But, he simply doesn't communicate very well. I just haven't had time to call him, but I have emailed him with very direct questions. Maybe it's not worth my time, but we'll see.
 
I may be overstepping here, but I've been in your shoes a few times. You're a motivated buyer it seems and want things to work out, possibly ignoring some warning signs along the path.....again, been there. I've gotten burned that way too, usually at swaps where I've given the benefit of the doubt to a seller, then found out they were clamming up for good reason. just because they're on the SYC site doesn't give them a pass. Like said, a 6223 crank has a history, and it's rare to find a gem, most are either junk or take some turning which eliminates the nitriding. There's one gent that sells on SYC, even has his own forum, and he sold me an expensive head and neglected to tell me it'd been welded. No big deal, it was in the center water jacket and it's relatively common for gm to have welded that up rather than tossing the head. Guarantee he was aware of it, and played it down once I received it.
If things feel funny, it's normally for a reason.
 
I may be overstepping here, but I've been in your shoes a few times. You're a motivated buyer it seems and want things to work out, possibly ignoring some warning signs along the path.....again, been there. I've gotten burned that way too, usually at swaps where I've given the benefit of the doubt to a seller, then found out they were clamming up for good reason. just because they're on the SYC site doesn't give them a pass. Like said, a 6223 crank has a history, and it's rare to find a gem, most are either junk or take some turning which eliminates the nitriding. There's one gent that sells on SYC, even has his own forum, and he sold me an expensive head and neglected to tell me it'd been welded. No big deal, it was in the center water jacket and it's relatively common for gm to have welded that up rather than tossing the head. Guarantee he was aware of it, and played it down once I received it.
If things feel funny, it's normally for a reason.

Well, I agree....I'm done with this guy. I reached out a few times even offering to call and chat at his convenience....and CRICKETS! I will keep searching...I know there are good guys to deal with, as I've had some great dealings for parts. So, I don't need the other type of seller...I'm done!
 
I just scored a std/std 6223 crank off ebay...seems like a good deal, so I snatched it up as soon as it was posted earlier today. It is not cross-drilled which I understand is no longer much of a thing as it was back in the day. But having std/std polished journals, magnafluxed & nitrided I figured I'd jump on this one! YAY!!!! I've been looking for a decent crank for about a year & a half!

Here's the ebay link: https://www.ebay.com/itm/185439358824
 
That's a pretty rare find. I'd take it in for a checkup asap. The crank guy I use here can get a forged crank polished down to 2rn, and they look purdy, kinda like this one appears.
 
A good aftermarket forged crank should be more than ample as you cannot see the stamping on the crank once the pan is sealed up anyway.
 
A good aftermarket forged crank should be more than ample as you cannot see the stamping on the crank once the pan is sealed up anyway.

I've investigated both Eagle & Scat crankshafts in my research. I have Scat connecting rods already, deciding they were likely much better than old dimple rods, etc. I understand what you are saying. Problem is, they are aftermarket and the price was going up even before the supply chain issues. They are both now easily $1,000 before shipping, if you can get one. I'm an old GM employee, so I will stay with an original GM crankshaft, especially now that I've found a nice one that's nitrided and has standard journals! Yes, I will hold my breath everything checks out, but it comes from a machine shop very visible on ebay as I've searched, and I believe I may have found a "keeper"! My build is a vintage 1967 build (L78), complete with many original date coded parts for the assembly date of the block I have, so just throwing parts at the build isn't part of the plan.
 
I receive a check from GM as well but but but. They aren't loyal to their customers so I owe them nothing. Design Defect Motors
 
I receive a check from GM as well but but but. They aren't loyal to their customers so I owe them nothing. Design Defect Motors
Only check I received from GM was for working in a very HOT Foundry!....Central Foundry Division of GM. I do have a few original GM stock certificates, but they aren't worth anything since the bankruptcy days. I worked there when Ed Cole visited one day...those were good days in the 60's when GM was spitting out our Chevelles, GTO's, etc. I will never knock GM, but I did quit, instead deciding to go into Civil Engineering instead of Mechanical Engineering. I wanted to design cars as a kid, but starting in the Foundry was a nail in the coffin - so to speak, for getting an opportunity to be in the design department. I much prefer small businesses, not huge corporations, so I left. It was a good experience overall learning all about malleable & grey iron from the core design dept, to the core room, to pouring iron, to finishing, and metallurgy department. Too bad those days are gone...we'd be much better off if all our parts were still made in the USA!
 
We'd be much better off if anything were made in the USA. I worked in an assembly plant and learned alot about how cars are/were built. I was once a pretty good metal man back then. Also got to do a bit of electrical repair when shit didn't work after assembly. I did enjoy my days building cars for sure.
 
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