The CN crank I was planning to use in my build (just south of 500 hp) is already .010 under, and my machinist/builder is saying he'd prefer to work with an uncut crank if possible (he hasn't ruled out working with this one). Is there really anything to be concerned about in regards to working with this particular crank? Everything else seems to be fine, it's just the previous machining that he's commented on.

Unfortunately I discovered yesterday that the rod bearings in my backup engine were toast and had pounded the crank in that engine beyond repair.

Finding a good, unmachined crank around this area is like looking for a needle in a haystack, but if I found one, paid for it then still had to pay for the machining including opening for a pilot bearing I'm thinking I'd be better off going to a new crank, like the Eagle.

Open to thoughts and suggestions here. I'm leaning towards telling him to use the CN crank unless he can give me some solid reasons not to.

The good news is he's already sourced cam bearings for me. The bad news is Edelbrock head wait times (nuff said!)

 

Get a reason why he doesn’t want to go .020.
Where'd he find cam bearings?

 

Another shop or supplier up here in Canada. He managed to find 2 sets, the other one's for a 400 he's working on. Don't think there were any more, and by the time he found them he was realizing how lucky he was to locate them.

 

I don't quite understand the problem cutting a Olds crank. To me they are very large. A 454 Chevy uses 2 1/4 rods, which is 1/4 smaller than Olds to start with. I know there is a lot more 454 Chevy built up with more HP than a Olds, so not sure where the problem is to turn to .030?

 

There is absolutely no reason you can’t cut the crank .020” or .030”

Take your crank somewhere else. Where are you in Ontario?

in south central the only good crank grinder is Ideal Machine in Woodstock

 

That's my thinking as well, just want to educate myself a bit before having my next conversation with him. From what I'm hearing so far there's no (apparent) reason not to use this crank.

I'm on the west coast, Southern Vancouver Island. I'm sure he'll do good work or I wouldn't be there in the first place, I just don't understand his reluctance to use this crank and wanted to make sure there wasn't some well known issue that I wasn't aware of. So far, I'm hearing none!

 

[QUOTE=VI Cutty;1426721I'm sure he'll do good work or I wouldn't be there in the first place, I just don't understand his reluctance to use this crank and wanted to make sure there wasn't some well known issue that I wasn't aware of. So far, I'm hearing none![/QUOTE]
Again ask him EXACTLY why he won’t go .020.

 

I intend to.

 

I’m no machinist. While I can understand the concern about the quality of previous machine work, it seems to me any new machine work would fix the screwups.

I have heard the accuracy of the aftermarket cranks are hit and miss. Unfortunately, having to double check parts, even new ones, is almost a requirement.

 

I've seen so many posts about Eagle cranks breaking. I'd avoid them.

 

I've seen mixed reviews on them as well. Talked to my machinist today and all is well, we'll be using the crank I have.

 

Could you please post some links to these posts ????

I have probably used a hundred Eagle cranks in the last 25 or so years in everything from stock rebuilds to all out race engines. Have never had a single problem with them. I have had a few that I didn't like the sizes on them so we had them reground and made right. Even with doing that you cant beat the price. Same deal with the rods.

I have found that almost every time that you hear about a crankshaft or rod failing it was some type of engine builder or tuneup error. Either that or it was in an engine that it should have never been in to begin with. You don't use a $150 cast crank in an 800 hp turbo small block.

 

As far as grinding the crank goes I have always used the rule of thumb that if Clevite makes a bearing for it then its ok to grind it that size.

Some factory cranks are nitrided and guys say you will grind through the hardening but I dont think that is the case with any Oldsmobiles. Guys grind Big Block Chevy rods down to Small Block size to get more stroke. They take 400 Chevy cranks and grind the mains down to 350 size to make 383 cranks. In both of those examples you are taking at least .100 off the cranks.

I think its old Wives tales that some guys dont want to forget

 

Thanks for the input, Bill. Most of the comments I saw were related to quality control, many of them were at least 10 years old and I did see some comments about the QC having improved considerably. I'm afraid I didn't save any of the links (just did a google search for Eagle Oldsmobile Crankshaft or similar wording) and a lot of the comments originated right here in CO. I didn't really look at failure comments as much as the out of the box quality observations. I didn't get far enough into researching cranks to start taking notes and sourcing options apart from noticing that the cranks I would love to consider are way outside my budget lol.

In various discussions I heard a few comments about some people cutting down even to fit Honda rods so I have no concerns with mine, and my machinist didn't hesitate to say "ok" to using this one when I told him we weren't going to find anything better around here. He did mention nitriding, but didn't think the Olds cranks had that done. All in all, we're making progress on the engine but I still have a lot to do on the car yet :-D

 

Honda rod journals are only done on small blocks, not big blocks. Virtually all stock cranks for the most part are basically just surface hardened. After the first grind its long gone. And for most power levels nitriding is not needed. You’ll break the block before you break the crank typically.
And the biggest issue in taking so much off any journal, is where the oil hole will end up. Taking .100 or so normally doesn’t pose a problem. When you start getting into a lot more than that it will.

 

That was more of a side note, certainly not representative of any of my plans! We'll be 20 under on this crank and no worries.

 

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