Ok I'm gonna kick this dead horse because it miffs me. Why would oldsmobile bother with a steel 455 crank if they were only going to be used sparingly and in weird combos like a 2bbl 98 etc. I could see as an option or package like the W30 or H/O but olds didnt. I have a theory that maybe they had materials left from the 425 and just used them up. Anyone have theories on this?

 

Probably thought it was a good idea, had some sort of production issues, high cost, and found a cheaper cast crank would do the job.... there's my guess.

 

I think you are close to the reason (and this is obviously only speculation on my part). Olds has traditionally shown that they tended to initially do things "the way we've always done them" when releasing a new engine design. For example, the first year of the new-for-1964 second gen V8 (the 330) used shaft mount rockers like the first gen Olds V* family. This lasted only one model year (actually, even a little less as some late production 64 motors got no. 2 heads with the pedestal rockers), at which point Olds switched to the pedestal-mount design.

I'm guessing the same thing happened with the early 455 cranks. ALL 1964-67 cranks were forged. It makes sense that the development 455s would be built using similar forged cranks. Olds apparently figured out early that the cast nodular cranks were more than strong enough and likely less expensive to manufacture, thus the early transition to those in 1968. I suspect they had to order a minimum quantity of forgings during development, so these were likely just used up. Since this was not the intended production configuration, it might have made sense to use them in the lowest-stress applications, since they probably weren't subjected to the durability and life testing of the production CN crank motors.

Just a guess on my part...

 

Olds made a limited run of forged cranks with a special H/O in mind, but when that didn't happen, they just used them up on the production line.

 

What special H/O? The 68/69 production cars or some other H/O?

 

one thing about oldsmobile.they used all their parts in inventory.years ago we overhauled a 455.think it was out of a 76 98.anyway everything was standard,cyls were within specs etc so we just honed the cyl's mic'ed the crank and just reringed it and new bearings.when we had the crank out we noticed it was drilled for a pilot bearing.so it was originally slated for a manual car.anyway.we get it all back together and in and start it up and we had somewhat low oil pressure.like 15 to 20 lbs at hot idle.
we ended up pulling the engine and pulling the crank.this time we plastigaged the crank.all 5 journals were different.and we dug up the old bearings and they were all marked different.the front was standard the second was .05 under,the third was .010 under the 4th standard and the rear brg was .05 under.so we just got separate bearings from the local olds dealer.put it back in and then we had great oil pressure. evidently olds figured it was cheaper to make under size bearings then to true up the block,and crank