Hi Turbocharged400sbc, all,
James: Should have known you wouldn't be familiar with the BS as it's been presented on ROP. Never doubted you'd know the metallurgy better than I.
While searching for a better thread to illustrate my point, I discovered the subject was already addressed.
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I thought that all cast iron cranks were nodular iron ........
They are. Internet was the first place I'd ever seen cranks referred to as nodular, instead of cast. It's also where I learned I had been doing impossible things with my Grey Coupe.
On ROP, Oldsfan1 wrote:
The N(large N, Small N, CN or no N) are all Cast Iron, cast from Nodular Iron ........ There is........ no difference in Iron Cranks as far as the metallurgy that went into making them even though, there have been well versed authorities making claims that a certain designation on a given Crank( N, CN, etc.) makes it better or worse than others ........
Not only did this answer the question, it's the first time (to my knowledge) anyone has actually come out and said it.
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........ what are they saying? That they used different iron in the cranks? ........
That's what has been said. The common belief on ROP, for years, has been, (I'm paraphrasing):
Use only a "nodular" crank. The one cast with the "N" is the strongest. Those with other marks are nodular and nearly as strong. Do not use an unmarked crank for a performance rebuild because it’s cast, not nodular.
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........ what the one gentleman (83 Hurst guy) said ........
As I discovered earlier today, he's one of several who have been trying to correct that misconception since about last October. He was the first to explain it fully.
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........ I don’t see Olds doing anything that "special" for production engines ........
Forged were used in all Olds V8s, from ‘49, to ’64, then in some ’65 to ’68s. All 330 and 400/425s were Steel. Only a few 455s were forged, as they found the (cheaper to manufacture) cast cranks to be more than up to the job. 67 was the last year for 330, and all 68 and newer BBOs used a 4.25" cast piece.
This one sold cheap.
This is a 330, but it fits all SBOs except the D/DX.
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…….. cast cranks just shouldn’t be pushed that hard ........
More than one BBO is running low tens using a cast crank. Some have lasted longer than others.
On ROP, oldsmobile_al wrote:
........ The crank was stock mains, 2.200 rods 4.500 stroke ........ The crank was nodular cast iron, over 300 runs, 6200 rpm, 9.50@143 ........ The car is 3000lbs with me in it, the crower steel rods were 6.700 long at 760 grams, the pins were around 125 grams, the ross pistons were 584 grams ........ the 300 runs are over three years, it was taken apart each winter and looked over, the bearings look like new even now ........ straps and studs only.
For more on Al's paperweight, click
here.
Regards, Norm
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