GM Forging #3967416
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GM Forging #3967416

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    Senior Member MACHINEHEAD1's Avatar
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    Default GM Forging #3967416

    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 Blowncat 509's Avatar
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    sounds like an ls-7 1053 steel nitrated crank to me- best gm oldschool
    crank for years IMHO

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    From a book I have:
    3963523 part number was ls-6/7 1053 crank. Crank ID was 3520 or 7416
    3963524 was the 5140. Crank ID was 3521.
    Last edited by Fiat48; 11-14-2010 at 02:26 PM.

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    Senior Member MACHINEHEAD1's Avatar
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    The only # on the crank is the 3967416 and a W50 on the counter weight next to it. What do I gots?

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    Senior Member fireboat607's Avatar
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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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    Is this full part number on the counterweight by the rear main?

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    Motec.com

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    huge member jimthetoolman's Avatar
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    Default Crankshaft

    Quote Originally Posted by fireboat607 View Post
    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?????


    I have a brand new never used one. $350.00

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    Senior Member MACHINEHEAD1's Avatar
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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.

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    Senior Member MACHINEHEAD1's Avatar
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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

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    Quote Originally Posted by MACHINEHEAD1 View Post
    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.
    Last edited by Fiat48; 11-16-2010 at 09:35 PM.

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    AKA Blownjet 468 Blowncat 509's Avatar
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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 wish I knew. They did show them as 1053 in the 97 catalog.

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    New here Beer:30's Avatar
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    Quote Originally Posted by MACHINEHEAD1 View Post
    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 . 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.
    Quote Originally Posted by gn7 View Post
    EFI is the wave of the future. There can be no denying it. Electronics have been on the leading edge of our entire lives. Not only os the magneto dead, but the standard issue CDI is wavering. Its all about total fuel, air AND spark control. Anybody that thinks its not has their head up their ass.


    2001 SleekCraft 30' Heritage SSB, open-bow mid-cuddy. 496HO / Bravo-I.

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