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401 vs 304?

Discussion in 'Intermediate CJ-5/6/7/8' started by Brent74cj5, Mar 13, 2008.

  1. Mar 13, 2008
    Brent74cj5

    Brent74cj5 Brent74cj5

    tennessee
    Joined:
    Jul 19, 2007
    Messages:
    29
    I am in the process of building a 401; I finally found a good block at an affordable price. I have a 304 in my cj now, and it runs good (when I can keep the fire burning in it... another story). I have thought about pulling the 304, and replacing it with the 401. Will the 401 mate up to my 3 spd, or do I need to get an adaptor? I am more than happy to research this, but haven't found it yet. Any suggestions?

    Of course, I can always keep the 401, get another jeep, build a monster HP motor, collect money for the rides to unsuspecting wanna bees, will need more stuff, 35's... R)
     
  2. Mar 13, 2008
    High5

    High5 Member

    Urbandale, IA
    Joined:
    Jan 13, 2005
    Messages:
    802
    It will bolt right in. Everything on the outside of the AMC 304,360,401 are the same.
     
  3. Mar 13, 2008
    High5

    High5 Member

    Urbandale, IA
    Joined:
    Jan 13, 2005
    Messages:
    802
    Except the flywheel. The AMC engines are externally balanced and you will need a specific 401 flywheel.

    High5
     
  4. Mar 13, 2008
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Medford Mass USA
    Joined:
    Aug 10, 2003
    Messages:
    23,596
    I've read that many of those 401 blocks are radioactive and that lengthy exposure can be unhealthy. I'm trained in this area - I would be happy to exchange your 401 for a good running 304 if you can just cover the shipping charges plus some nominal handling charges. :coffee: ;)

    (The 401 has exactly the same external dimensions as the 304 - the swap couldn't be easier. You need a 401 flywheel - the balance is different from the 304 or 360 - available from aftermarket sources. Everything else is the same. Use your existing bellhousing and clutch linkage. Note the T-15 is strong, but maybe not 401 strong. How long it and the rest of the drivetrain lasts will depend on your driving habits.)
     
  5. Mar 13, 2008
    fuzz401

    fuzz401 New Member

    lancaster pa
    Joined:
    Oct 18, 2005
    Messages:
    30
    if you have a lead foot things will break
     
  6. Mar 13, 2008
    LostDawg

    LostDawg Slowly rusting in the NW

    Longview, WA
    Joined:
    Sep 24, 2006
    Messages:
    300
    :drool::drool::drool:
    You will find your weakness, but Dude... finding them will be a blast!
    Just a hint, when you do drop it in your CJ, just be aware of torque steer... if you hammer it and then suddenly let off the gas, it will want to pull to the right. I noticed it when I went from my 304 to a 360, and I imagine a 401 will be at least as pronounced if not more. Not a big deal if you're expecting it.
    I'd say go for it! :)
     
  7. Mar 13, 2008
    Brent74cj5

    Brent74cj5 Brent74cj5

    tennessee
    Joined:
    Jul 19, 2007
    Messages:
    29
    Timgr

    I appreciate the offer, but I think I'll keep my 401. If you're interested, here's the name of the company I got it from. Drivetrain Parts Source, Lewisville, Texas, 800-436-6802. It was the only 1 they had at the time. Just don't let em talk you into heads, intake, etc. They're a good company, but when you work for a living, you can only buy 1 part at a time.

    Thanks for the help folks! As usual I can always depend on my fellow jeepers/jeepsters/jeepologists/jeepographers. R)
     
  8. Mar 13, 2008
    Warloch

    Warloch Did you say Flattie??? Staff Member

    Falcon, CO
    Joined:
    Mar 4, 2003
    Messages:
    5,466
    There is a 401 block for sale here in CO on the Colo4X4 board... NO - I don't want it as I will stick to the 360 in the commando.
     
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