I have a motor with an arma steel crank and was wondering what the chance of having forged steel rods also, is there a way to tell the diff without pulling it all apart?

Seems to me the tell tale would be foundry cast seams sowing up on cast rods.

The casting "seam" is just that, a very narrow "line" up the center of the side beams. A forged rod will have a much wider "parting line", at about 1/4".

"ArmaSteel" is another "name" for cast iron. It was rumored this was "leftover" armor from WWII. Whether or not that's true, I can't say. Nothing "special", though. No beetter than any of the "N" cranks.

Jim

I'll post a side by side comparison pic tonight. I've got both out in the garage..

--Kyle

I have a arma steel crank in my ho. the crank a high pitch ring (when tapped) for the fordge steel crank. the casts have a low pitch ring and the metal color of the crank is not as bright.

The forged rod is on the left with the piston. The cast on the right has a very small line.



The forged rod line is 3/16 inch wide

great pics thanks for the lesson.

Thanks Jerry,
If you need anymore pics let me know

Kyle

ho4spdtogo,

I'm afraid the "ring test" is highly unreliable. That was how cranks were "checked for cracks" in olden times, when "wet" magnefluxing was reserved for "high end" shops. The cast crank you "rang" might have had a crack, and that's why it "sounded funny". I've "rung" three here today (N, ArmaSteel and forged), to see if I could tell a difference. All sounded about the same. You might remove the woodruff key in the snout, and "rering"...

AramSteel is definitely CAST, and not forged. The nodular ("N") cranks ARE as good or better. They changed many of the processes in the mid '60s, as metalurgy knowledge increased. This isn't to say the AmraSteel cranks aren't good, of course they are. Chevy boys would KILL for a cast crank that could "take" 750 HP. Sorry if I "rained on your parade", but I've seen this before, and they aren't anything "special" compared to the nodulars.

Jim

no problem "mr. P" still driving it and no probs with maging it. I knew there would be some disagreements and the test is a quickie; but, having 30 yrs of pontiacs under my belt i seen both kinds of cranks.

i did a google search to see if i was crazy. found some interesting info on the chev sites. you should check it out.

Had at one time.

2 aftermaket 4340 steel cranks.
1 990(61-421 SD)
3 N cranks(400&455)
2 armasteel

The 990 had very distinct ring compared to the others.
The arma had just a tad more the the N's.
Cant remember, but one type(arma vs N) was little heavier then the other.