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Thread: crank 2nd keyway

  1. #1

    crank 2nd keyway

    OK, here goes. I had a motor (sbc 350/671 blower 8.5 compression plan on 6#boost) built by a local "company", they build/built racing motors but I'm not sure how many blower engines they have built. Here's the rub, the motor is all together less the blower which I will put on. I have been reading up on this and every artical I read says the crank MUST have the 2nd keyway cut, well it doesn't. So has anyone ever cut one without removing the crank from the motor or is that just NOT an option. Since we are "only" running 6-7 lbs of boost do we really need the 2nd keyway? And ofcoarse these guys are no longer in bussiness and I will have to take it somewhere else to have it done. Any help out there? thanks!

  2. #2
    Senior Member MASTER BUILDER
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    Re: crank 2nd keyway

    Quote Originally Posted by kenglish
    OK, here goes. I had a motor (sbc 350/671 blower 8.5 compression plan on 6#boost) built by a local "company", they build/built racing motors but I'm not sure how many blower engines they have built. Here's the rub, the motor is all together less the blower which I will put on. I have been reading up on this and every artical I read says the crank MUST have the 2nd keyway cut, well it doesn't. So has anyone ever cut one without removing the crank from the motor or is that just NOT an option. Since we are "only" running 6-7 lbs of boost do we really need the 2nd keyway? And ofcoarse these guys are no longer in bussiness and I will have to take it somewhere else to have it done. Any help out there? thanks!
    2nd keyway???....why??...the balancer is a press like fit and the bottom blower pulley bolt to the balancer....I might be able to see it if you were running a 14-71 with tons of boost....

  3. #3
    Senior Member RACING JUNKIE
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    the key way has to be cut on a mill, i forgot the purpose of the
    second key way but my lunati crank came with 2, and can't
    remember the reason but it's there, good luck :wink:

  4. #4
    Senior Member MASTER BUILDER
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    671 blower 2nd key

    checkout add #1287512. There is a lot of stress on the front of the crank when using a blower. Needs to be cut 180degrees from other key. There are wieand street kits that people buy to put on a stock engine that do so w/o pulling the engine down. I dont remember this kit for adding a key being around about 10 years ago or more. I had to make my own to cut the 2nd key in. Kris

  5. #5
    Senior Member EXPERT BUILDER
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    All the blower eigines we have built have all had a second key way and it can't be done in the engine.

    It sounds like your going to roll the dice on this one and most guys will use the BBC snout
    WWW.CNCBLOCKSNE.COM
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  6. #6
    Senior Member RACING JUNKIE
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    Re: crank 2nd keyway

    Quote Originally Posted by kenglish
    OK, here goes. I had a motor (sbc 350/671 blower 8.5 compression plan on 6#boost) built by a local "company", they build/built racing motors but I'm not sure how many blower engines they have built. Here's the rub, the motor is all together less the blower which I will put on. I have been reading up on this and every artical I read says the crank MUST have the 2nd keyway cut, well it doesn't. So has anyone ever cut one without removing the crank from the motor or is that just NOT an option. Since we are "only" running 6-7 lbs of boost do we really need the 2nd keyway? And ofcoarse these guys are no longer in bussiness and I will have to take it somewhere else to have it done. Any help out there? thanks!
    Here you Go?
    AD#1287512 in the Classisfied.
    This will do what you NEED!!!
    I have always Doubled Keyed My Blower
    Motors,but that was because we ran in Excess of 25lbs og BOOST!
    I have a Street Deal going as we Speak,and i beleive that this Fixture is going to get a Try?
    Later
    G 8)

  7. #7
    Senior Member RACING JUNKIE
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    Re: crank 2nd keyway

    Quote Originally Posted by radicalz
    Quote Originally Posted by kenglish
    OK, here goes. I had a motor (sbc 350/671 blower 8.5 compression plan on 6#boost) built by a local "company", they build/built racing motors but I'm not sure how many blower engines they have built. Here's the rub, the motor is all together less the blower which I will put on. I have been reading up on this and every artical I read says the crank MUST have the 2nd keyway cut, well it doesn't. So has anyone ever cut one without removing the crank from the motor or is that just NOT an option. Since we are "only" running 6-7 lbs of boost do we really need the 2nd keyway? And ofcoarse these guys are no longer in bussiness and I will have to take it somewhere else to have it done. Any help out there? thanks!
    2nd keyway???....why??...the balancer is a press like fit and the bottom blower pulley bolt to the balancer....I might be able to see it if you were running a 14-71 with tons of boost....
    #1 James,
    Using a Balancer on a Blower Motor is the 1st MISTAKE!!
    Always use a Blower Hub,that way you have 6-Bolts on the Lower Pulley.Verses the 3-with a Balancer.
    Had a Fellow Years back that would Tear Off a Steel Balancer about Twice a Month until i Double Keyed the Crank,and Installed a C/M Hub!
    Later
    G 8)

  8. #8
    2nd keyway is a darned good idea if only for piece of mind at 7 lbs.
    Balancer should be one with a steel center. OEM (cast) is going to be a problem.

    ATI makes them with 3 bolt chevy pattern or the 7 bolt chrysler pattern. Just depends on what style pulleys you are using.

    Don't know where you are but if it helps, keyway cutting for blower hub use is something I do about once a month.
    Any perf. machine shop or even a general machine shop should be able to handle this.

    Dave Koehler
    http://www.koehlerinjection.com

  9. #9

    THANKS

    thanks to thosw who replied! I will be using that pinning tool. :lol: :lol:

  10. #10
    Senior Member RACING JUNKIE
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    I cant belive how when it comes to blowers the answers that come out. lol
    Do not run a stock balancer
    You do not need more than one key for a detroit 671


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