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Discussion Starter #1
All I have found so far is that it is forged, 70-71, 454. I would like to know what material, is this a special crank, what it came out of? BTW mine is cross drilled and has a darker color than normal. Just curious, its out in the shop and says "mag OK." Thanks for any info.
 

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AKA Blownjet 468
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sounds like an ls-7 1053 steel nitrated crank to me- best gm oldschool
crank for years IMHO:p
 

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In my Chevy book it say's LS6 / LS7, forged 1053 steel, cross-drilled, nitrated....the high-end of BBC factory cranks, good stuff!

Anyone can pedal a bicycle, can you pedal a flat?????
 

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Discussion Starter #9
Yes Fiat, this complete number in on the rear counterweight. To answer the above question of "Pedaling a Flat," I have a Flat bottom Hallett. But I dont pedal it much since it has a Nailhead in it. Or are you asking if I want to sell it or the crank? Or does my boat have pedals, like a Flintstone boat. Or are you using some sort of kool jargon, only being used for the first time.
 

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Discussion Starter #10
I looked at a site that I think old guy was prompting. Im not really interested in a bad ass fuel/engine management system right now. But if I am I will go MOTEC. WTF is going on here. What ****ing crank do I have. Jesus. BTW Thanks Fiat if you got something on this
 

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Yes Fiat, this complete number in on the rear counterweight. To answer the above question of "Pedaling a Flat," I have a Flat bottom Hallett. But I dont pedal it much since it has a Nailhead in it. Or are you asking if I want to sell it or the crank? Or does my boat have pedals, like a Flintstone boat. Or are you using some sort of kool jargon, only being used for the first time.
Then here's the story...best I can do.
Best I can figure....this is a remake of the LS6/7 crank. A new forging. If you compare the front counterweight to a "normal" chevy crank...you might notice the counterweight is "smaller" (not narrower). Get a visual by looking at another crank.
If this is the case...those cranks flex a lot. I bought 3 of these new (same part number as the "old" LS crank) and all 3 motors they went in had bearing problems. One was in an unblown alcohol altered, One in a monster truck deal and one in my own blown alcohol car. I toasted bearings first (one pass).
I put some rediculous clearances in my motor and it continued to live. I loosened the other motors up and they too stayed alive.
So if that proves to be what you have...be aware of that.

The old cranks just had the ending of the part number on the first throw of the crank. These new ones had the full part number on the rear.
I bought these in the 90's....want to say about 1997.
 

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AKA Blownjet 468
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hey Fiat, does that mean that the newer ones that you called remakes
are possibly not the same material, prob 5140, instead of the 1053steel
that the "good old ones" were made from?
 

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I looked at a site that I think old guy was prompting. Im not really interested in a bad ass fuel/engine management system right now. But if I am I will go MOTEC. WTF is going on here. What ****ing crank do I have. Jesus. BTW Thanks Fiat if you got something on this
No no. He was saying go to "Mortec" website. The last time I did, though, it was no longer in operation :mad:. Anyway it had all of the SBC/BBC casting/stamped numbers all listed and easy to sift through.

Yes - MOTEC is an outstanding management system. Coil per cylinder, etc. Nice.

Just do a google search on your crank number and you will find all you want. It has already been ID'd here, but if you need more assurance - just search on it.
 

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According to old parts books I have:
3963523 crank was 1053 and used in engine assembly 366250....which is known as the LS6 motor with 10.2 compression.

3963524 crank was 5140 and used in engine assembly 3965774...which is known as the
LS7 motor with 12.25 compression.

That said...I assume the 5140 was what I was seeking way back then and got the 1053 instead. I think.

Yet the 97 catalog stated "This forged 1053 steel 4.00 stroke crankshaft is used in LS-6 and LS-7 big block V-8's."
But hell you couldn't get an Ls-7 in 1997.

I think that statement in the 97 catalog was typo.
 

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Discussion Starter #16
Interesting what has been said about the bearing clearences. This crank is m/10 t/20. I think it came out of a mercury blue 465HP that had been factory re poped. It does show signs of a snug main fit across the board. The final straw for this mota was a old dead set of head gaskets. Its all coming back now, 86 Cafe Racer w/trs. What a project. Thanks to all. Prob just sell it.
 
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