3500 crank

[34blazer]

If your judging by the sound, all the literater I can find on the subject says a steel crank will ring and a nodular iron will thud. Just because the outside appears to be cast doesn't mean it is, look close at your forged 60* rods - they appear to be cast.

in that case hopefully someone can verify with a definite answer. because im unsure im gonna do some research on how to actually determine the testing. i just dont want to go out and buy 2 or 3 3500 cranks to find out they are cast, because id like to have a crank to support my hp goals.

[ForcedFirebird]

from where i sit, its cast. thanks dave

If your judging by the sound, all the literature I can find on the subject says a steel crank will ring and a nodular iron will thud. Just because the outside appears to be cast doesn't mean it is, look close at your forged 60* rods - they appear to be cast.

[ForcedFirebird]

from where i sit, its cast. thanks dave

The casting markas are the same as a forged GM crank, it's hard to tell until someone can talk to them and get a solid answer.


Either way it appears to be much better built then the predessesor.

[34blazer]

I took a bunch of pics... here:

http://www.3500z.com/Gallery/main.php?g2_itemId=741&g2_page=2

http://www.3500z.com/Gallery/main.php?g2_itemId=741&g2_page=3

the crank is just sitting in the block, if you need any pics of different spots just let me know.

from where i sit, its cast. thanks dave

[ForcedFirebird]

Also notice the 7484 crank is almost completely machined, whereas the older 981 cranks are almost completely cast (except in the journal areas). Even this process would make it much stronger even if it was iron because it is closer to being "billet" - or machined out of a large piece of stock, rather then being molded to shape.

[ForcedFirebird]

7484 is the designation number on the snout.

If it has the wide seem line it's steel even if you can't find the last 4 digits of the steel crank part number on the crank snout. I don't remember what they are but they're posted. More importantly they probably only used the cast iron crank in the early engines as I have only seen one in a picture on this forum side by side with the steel version and it had the characteristic thin seam line on the front throw.

I recall the debate I had some time ago here after noting that my crank looked funny compared to what I was used to a cast crank looking like. I called GM parts direct and was given two part numbers for the 3500 crank the difference being the cost and the shipping weight of the crank, my numbers matched the heavier more expensive crank and along with the pictures confirmed it was the steel version. It proved that just because GM didn't say it, it doesn't mean it isn't so.

Forged or not, it should be considerably stronger than the iron crank and lets not forget the benefit of the larger diameter throws for increased bearing load distribution and further stiffening of the crank to make high rpm safer. The fuel cutoff at least for the 3900 was bumped up to about 6400 rpm and thats with a heavier reciprocating mass. I don't see any cause for concern with the crank.

[ForcedFirebird]

The tone is a little different, but as I have said before they both ring about the same amount of time.

Seeing that they have different size reluctor rings and rod journals, they could easily have different tones just from the mass of each.

[TurboGTU]

You usualy have to hold the crank by the snout isolated with a towel and hit the end of the crank. BUt it seems to be steel. I would be happy just beeing steel.

[Superdave]

dave can you tell by looking around the throws if its cast or not? if you can can you post some pics?

I took a bunch of pics... here:

http://www.3500z.com/Gallery/main.php?g2_itemId=741&g2_page=2

http://www.3500z.com/Gallery/main.php?g2_itemId=741&g2_page=3

the crank is just sitting in the block, if you need any pics of different spots just let me know.

[34blazer]

dave can you tell by looking around the throws if its cast or not? if you can can you post some pics?

[ForcedFirebird]

Here you guys go...




http://media.putfile.com/3500-LX9-Crank

My 3.4 crank sounded like that too.

[Superdave]

Here you guys go...

http://media.putfile.com/3500-LX9-Crank

[blkalero]

the forged crank has a very fat casting line

[rsisbetter]

sounds good