- crankshafts - austin hearnen 7/29/00 2:29
Are the early armasteel cranks stronger than the later nodular iron cranks? should i have the crank cross drilled for high rpm use?

Responses

Jerry Coffee Bio 7/29/00 3:58
The 1966-and Armasteel cast cranks are not any stronger than the 1967-up cranks with a "N" cast on them. Both are nodular iron. If you have the crank crossdrilled, you should not use fully grooved main bearings. It can't hurt but if the rods are prepared correctly and the assembly is completely enternally balanced it is not necessary. I double cross-drilled my 1967 Firebird 400's crank but I was using solid lifters and running over 6000 RPM. Keep it under 6000 and everything will be OK.

- John V. 7/29/00 9:11
I am not a metallurgist, but I believe Armasteel is a tradename for a type of pearlitic malleable iron. You can look pearlite and malleable up in the dictionary. Malleable suggests it can be shaped by beating with a hammer or pressure of rollers. Nodular is not so clear to me in the context of iron. However, I would think there is a difference based on circumstantial evidence. Didn't Pontiac use an Armasteel crank for the round port ram air motors while the nodular iron cranks were used in "regular" motors? Maybe it is not stronger, but it seems to me there must be some difference.

Jerry Coffee Bio 7/29/00 10:02
The last year that the Armasteel logo was use on a crank was in 1966. The factory determined that it was misleading because the cranks were not steel. The 1967-up cranks had a "N" casting meaning nodular, or the cranks had no logo at all. Nodular cast iron, also known as spheroidial graphite iron, is that the graphite is present in ball-like form instead of flakes as in ordinary gray cast iron. This results in a casting of high strength and appreciable ductility. It's toughness is intermediate between that of cast iron and steel. It is more economical to make than steel because it can be cast in molds by the millions.

Jerry Coffee Bio 7/29/00 10:06
I had a RA IV engine and the crank had a "N" cast on it along with the RA IV crank part number.The only difference between a standard 400 CI engines's crank and the RA IV crank is that the RA IV crank was machined with .001" more clearance on the rod and main journals. Otherwise they were exactly the same.

IgnitionMan Bio 7/29/00 10:56
Armasteel cranks were Pearliic Malleable iron, with enhancements, are not drop cast poured, but are centrifugal spin cast. Armasteel is less prone to cracking and pounding damage from detonation, not much, but a little more, and is more dense in its basic structure. After the main casting process is done and the basic machining is completed, the fillet radiuses and main/rod journals are rolled in a hydraulic former, to make those areas stronger (about 10 to 15 percent stronger) than either drop cast or machined areas of the cranks. Buick also used armasteel cranks, withoout problems, and all V6 buick cranks, steel or iron, have rolled, not machine cut or ground fillet radii. Camshafts used to be made in two different materials, nodular and pearlitic iron, non-hardenable and hardenable, for flat tapet cams, one for hydraulic and the other for solid lifter use.

- Don donfmac@earthlink.net 7/29/00 12:19
I have a 428 arma steel crank in my 440

- Todd farland@cts.com 7/29/00 12:25
And to further muddy the waters as to why some Pontiac engines in the mid-sixties got Armor-Steel cranks while others did not, note that **ALL** 65 326 engines (including the 326 2bbl, auto trans engines) got Armor-Steel cranks. Go figure...

Jerry Coffee Bio 7/29/00 12:30
The 326 Pontiac engines got the stronger "Armasteel" cranks because of the incredible amount of HP the were producing.

Socrates Bio 7/29/00 13:28
Sorry, Don, but from what I've found, no 428 armasteel cranks ever made. Many 421's cranks were armasteel, but none found in 428's...Yeah, it is essentially the very same crank, but to get technical, Pontiac never used it in the 67-69 4" stroke engines.....

Jerry Coffee Bio 7/29/00 13:51
The last year the Armasteel crank designation was used was in 1966. Therefore no 428 or 400 cranks were called Armasteel cranks. They were all "N" cranks.

BillyS Bio 7/29/00 23:51
I have a 1968 428 4 bolt and it has a arma-steel crankshaft. It says so on the crankshaft. I know for sure this engine was never taken apart, and all is original. I think there were a few selected engines other than the 421's that they stuck the arma-steel cranks in, and the 428 was defenetly one of those. thanks, BillyS

Socrates Bio 7/30/00 2:41
I have an "armasteel' crank in my 428 as well. The part number clearly puts it as a 63' 421 crank (or a 64', can't remember which year offhand). I think Jerry has the right scoop here. Much can happen in over 30 years, even it The Song Remains the Same....

Jerry Coffee Bio 7/30/00 3:57
The 1963 421 #9770488 and the 1964-66 421 #9783787 crank is Armasteel. Then Pontiac started playing the "switch-'em" game with the 1967-69 428 cranks and pistons. The 1964-66 421 #9783787 Armasteel cranks were used until the #9782769 "N" crank was introduced in 1967. The latter was balanced for the different type 1967-69 428 pistons. Apparently a few of the 1964-1966 421 Armasteel cranks and pistons were installed in the 1967-69 428 engines. The 1967-69 #9782769 "N" cranks are difficult to rebalance for replacement TRW 428 pistons. But as a general rule, all 1967-69 428 cranks are "N" cranks and not Armasteel.

Jerry Coffee Bio 7/30/00 9:32
Michigan is a no deal area for me. I formerly delt with a guy somewhere near Detroit and he was a habitual fabricator and a thief. He claimed to have all kinds of 421 SD parts to trade. I found out that he did have what he claimed but they were just bait. He had a extremely rare 1963 421 SD aluminum steering sector. It was for barter purposes only. He may be deceased because I have not heard from him in 8 years. He used to call me every night trying to trade for a rare part that I had. We did do some trading however.

Jerry Coffee Bio 7/30/00 10:07
Crap, I posted the above in the wrong topic.

- John V. 7/30/00 10:24
Jerry, the '64/'65 421 HO Armasteel crank is 9773384, a '64 p/n. The '66 Parts Catalog (Aug '65 printing I believe) shows the 9782769 as the 421 & HO crank, so it was intro'd a year before '67. I also disagree about no difference on the RA crank. When the so called RAII was developed it had it's own specific crank casting, 9794054. It was marked Armasteel (only example I've seen) and was also used in the '69 RAIV. The regular '68 400 crank was p/n 9773524, a nodular iron crank. I understand the machining difference, but it makes no sense to have the RA crank cast as "Armasteel" at the same time nodular iron cranks were produced if there is no difference except bearing tolerances. IgnitionMan gives a very good description of what the Armasteel crank offered. Only thing unclear is whether he is comparing the process to the nodular iron cranks. Are nodular iron cranks "drop cast poured"?

- Don donfmac@earthlink.net 7/30/00 14:51
Concerning the arma steel 428 cranks..I was told mine came out of a 68 big car 428.. And i wondered myself iff it was a 421 or 428 crank so i got the numbers off of it checked every source i could at the time didnt tell anyone what i thought the crank was( other than pontiac )and everyone came back with the same answer 1968 428 crank. Now the crank is installed and I dont have the numbers handy, the issue was closed when i got my findings.

Jerry Coffee Bio 7/30/00 16:17
OK .....Lets do the numbers game some more. The standard production and RA 1967-1968 400 cranks were an "N" crank, p/n 9773524. The 1969-1970 RA III crank was a "N", p/n 9795480. The 1968 RA II (w/#96 round port heads) and the 1969-70 RA IV cranks were "N" cranks, p/n 9794054 with .001" more claearance than standard. I observed the "N" on RA IV crank when I dissassmbled my 1970 RA IV engine. Anyone that sees this should jot it down for future reference because it is correct and verified.

Jerry Coffee Bio 7/30/00 16:31
Don, if the crank was a 1968 428 engine it could have either a armasteel #9783737 421 crank or a "N" crank, #9782769,depending on the production date. The latter is considered the 428 crank and were used in all the late production 1968 and 1969 428 engines. Since you were told it was a 428 crank, the crank should have a nodular iron #9782769 crank in it. Apparently someone confirmed the casting/part number on it.

BillyS Bio 7/30/00 16:59
I always keep records especially when i send parts out for machining, (doesn't everybody?). Anyhow from my records it shows # 9783787 or did i read it wrong and it said 3737? thanks BillyS

Jerry Coffee Bio 7/30/00 17:25
The p/n 9783787 is correct for a 1964 Armasteel "421" crank. The #9773384 Armasteel crank was introduced in the 1965-1966 engines. Either of those cranks could have made it into some 1967-1968 "428" engines even after the #9782769 428 crank was introduced in 1967. Some on this thread say they did.

tboy Bio 7/30/00 18:42
Jerry,when did pontiac go to the long snout on cranks?A 63 crank I know has the short snout,how would it work in a later motor?Tom

geok Bio 7/30/00 19:02
Is it possible to have a arma-steel crank in a 68 400 block? The reason I ask is: I was told that's what my motor has in it after the rebuild. I didn't build it and I'm not that familiar with pontiac motors. According to this thread it wasn't available. Is there any way to check the crank with out taking apart the motor?

bvr421 Bio 7/31/00 0:13
Only Superman has X-RAY vision. With the pan OFF you can see the casting #'s.

geok Bio 7/31/00 20:53
Bvr421- sorry. I was just wondering if there was a casting number on the ouside or something. Or even if it was a possibility to have the Arma-steel crank. I don't have the details on this engine but with the performance (11.88 @~120mph) I want to find out as much info as I can to duplicate it if I ever have to.

bvr421 Bio 7/31/00 21:12
geok I dont know any way to find out other than looking at the casting #s on the crank. And if you can run 11.88 you got me beat by a mile. Sounds like a very decent combo. How much HP do you suppose that armasteel crank would add?

Mr6x Bio 8/1/00 19:52
Ignition Man describes the hydraulic rolling process well. Very interesting! Is this the same method used on the SD 455 and Turbo 301 cranks? What material was used for these?

geok Bio 8/1/00 22:00
bvr421, I don't know how much hp the armasteel crank adds. I'm still trying to figure out what else was done to this motor. That's the problem you get when you buy the motor already done from some one that needs cash badly. A couple of my friends (both big time pontiac-heads) were impressed with the motor and both said it tachs up faster than a sbc. Anyway, I'm getting a little carried away off-topic in this thread.E-mail me if you're interested(address in bio) and I'll let you know what I did verify so far.