HurstLightning84

Hey Guys! Hoping to shed some light on this. I'm rebuilding a 1970 350 block, and I'm slowly gathering parts to put it back together. I recently just snagged a used crank which i was told was a nodular crank, however after doing some online research it sounds like it goes back and forth. Hoping someone has a straight answer. I've looked at 442.com, but it too has conflicting info. It's stamped 393654, however does have the big "N" on it as well. Anything else I can look at to identify where this bad boy came from? Thanks!

Fun71

I'm curious, why do you want to know "where it came from" if you already know it's a nodular 350 crank?

HurstLightning84

That's the issue. Is it infact a nodular crank? A couple things I read online say it's from a 74' but it's just a plain iron crank, but was told something different. I'm just learning as I go on how to make this engine work at it's best, and I see that the nodular crank are what most prefer. Thanks!

olds 307 and 403

The big N is a dead giveaway. I have owned a few later cranks, have never seen an N on one. I believe some 74 cranks may have been the N cranks. Unless you are really pushing that 350, a later crank is fine. Where is the crank from the 70 block?

wr1970

What difference does it make! Really there is no proof that the N crank is any better than a cast crank.

joe_padavano

^^^THIS!

A nodular crank IS a cast crank. Pretty much all Olds cranks from 1968 to the mid-70s were cast from nodular iron.

ecwieder

Edit: just saw Joes reply. So guess my whole thesis is wrong
The nitride treated cranks seemed to wear a little better. Just pulled one from a 455 with 150000 on it and the journals and mains were still at new STD. spec. Not that that's the only, or even main factor affecting wear. I still had to have the crank cut because of scratches but it only needed .010 to get nice. Which by the way takes most of the nitride treatment out of the journals. I think the nitride treatment was more for warranty cost engineering than any performance issue. If they could get some % of engines to go some % longer before needing service under warranty the green eyeshades guys would be happier.
So if you check the crank and it's more than .010 under it might as well be a normal crank.

joe_padavano

The are all nitride treated, and that treatment is machined off the first time the crank is turned.

wr1970

^^^^^this

wr1970

Just because you can lead a horse to water doesn't mean he will take a drink. I am amazed how all this bad info gets spread around about these cranks.LOL. Anyone find that solid main web 403 yet?

HurstLightning84

I appreciate all the info! Like I said this is new to me trying to put all these parts back together. My goal is to get as much stock parts as I can get so I can put it back together and hopefully never have to crack it open again.

HurstLightning84

I figured it was, but like I said, all the info I've read has a lot of conflicting info. Just wanted to see everyone's input on it as well. Unfortunately when I got this block, it was just a bare block with no rotating assembly. Although, this one has a bit of rust from sitting on it, hopefully it still cleans up nice.

joe_padavano

Every 1964-1990 Olds gas small block uses the same main and rod bearings and the same throw. If you want the best possible factory crank, get a forged crank from a 1964-67 330. These drop into any small block Olds motor, though you would be smart to rebalance for your actual reciprocating mass. The 64-67 motors use a different crank flange bolt pattern, so you also need the matching flexplate.