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Amc 401

Discussion in 'Jeep Truck and FC Tech' started by Ol Fogie, Apr 25, 2020.

  1. Apr 25, 2020
    Ol Fogie

    Ol Fogie 74 cj5 304, 1943 mb

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    Are all factory AMC 401 engines equiped with a 4-barrell carb? or did some of them have 2-barrell carbs.
    I found a mid 70's j-20 truck that is parked and parts for sale. The guy who has it said he thought it is a 401 but it has a factory 2-barrell carb, I am thinking it's probally a 360.
     
    Last edited: Apr 26, 2020
  2. Apr 25, 2020
    DrDanteIII

    DrDanteIII Master Procrastinator

    Milford NJ 08848
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  3. Apr 25, 2020
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

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    Yes, all 4V from Jeep. IHC used the 401 for a few of their trucks and these trucks came with a 2V (something about their engine plant on strike or? normally they would use their 392).

    NB the 401 have a valve cover tag with a Z. The VIN will have a Z in it. The definitive test is the cast-in displacement, seen above. 5 years only, '74-78.

    This post is topical for either the FC/J-truck sub-forum or the Intermediate sub-forum. Suggest it is moved and saved.
     
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  4. Apr 25, 2020
    Ol Fogie

    Ol Fogie 74 cj5 304, 1943 mb

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    Thank you
     
  5. Apr 26, 2020
    Ol Fogie

    Ol Fogie 74 cj5 304, 1943 mb

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    Well I went back and looked at the truck again. This time I removed the air cleaner and looked, I was wrong it is a 4-BARREL carb on a factory intake. Got the VIN # off the truck and found this on line.

    VIN : J4A462ZZ361XX

    This vehicle's data:

    Year 1974
    Plant /Transmission Toledo - Automatic, Left Hand Drive
    Model Truck, J-20, 131 inch Wheelbase
    Body Style Townside Truck
    Engine, Body Type & Gross Vehicle Weight (GVW) Rat Early = 8000 lbs GVW, model 46 | Late = V8, 401 CID
    Engine Code V8, 401
    Model Year 1974
    My next question is: This engine being attached to an automatic trans with a flex plate, can it be converted for use with a straight shift trans by changing to a flywheel and clutch assy? How would the engine be balanced, internally or externally?
     
  6. Apr 26, 2020
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

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    Yes. 401 flywheels are available aftermarket, clutch parts are the same as the 360s. External balance, like the other AMC 3rd generation V8s.

    Why is it parked? These engines can be expensive to rebuild. Typically they cannot be over-bored more than once without needing sleeves.

    If it has an issue, the most likely problem in that era would be with a Borg-Warner Quadratrac. Possible that it's a Dana 20 instead of the Quadratrac. The J20s did not adopt full-time as quickly as the Wagoneer and J10.

    Don't spend any money until you look at the side of the block. Cast-in numbers are the definitive test. Many 401s have been taken out and replaced with 360s.
     
    Last edited: Apr 26, 2020
  7. Apr 26, 2020
    Ol Fogie

    Ol Fogie 74 cj5 304, 1943 mb

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    Tim, Thanks for the info. The truck was parked in the woods behind a body shop 8-10 years ago because of a 360 roll over accident. . The shop owner wants it moved and cannot locate the original owner, probably deceased. The body totally ruined. The truck supposedly ran well and was a daily driver. The inside dash assy. and steering column has been has been removed, therefore mileage is unknown. The truck appeared to have been well cared for and is totally unmolested with all engine pollution controls, engine accessories, factory wheels and so on intact. It does have a Quadratrac badge on the front fender. I will return to look more when I have more time, I was very late when I was there almost dark. I could not see the casting # on the block and the truck is totally covered in briers and brush. will take a lot of work to get in and examine well. If I purchased it I would not offer much more than scrap metal or core value.
    I am a bit challenged when it comes to balance in these engines. If a new flywheel is installed would it be a simple bolt on or would you need to have the engine and new flywheel re-balanced as a complete unit at some shop?
    Do you think the axles(and 8-lug wheels) would have any resale value?
     
    Last edited: May 6, 2020
  8. Apr 26, 2020
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

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    Balance. External balance (aka Detroit balance) means that the flywheel and harmonic balancer contribute to the balance of the rotating assembly. Internal balance (aka neutral balance) means that the external rotating parts do not contribute and are balanced on their own. All (most?) inline sixes are neutral balance. Many V8s are externally balanced.

    There is a specific 401 flywheel that matches the balance of the rest of the 401 rotating assembly. It's different from the 360 or 304 flywheel. There is some evidence that AMC matched the flex plates not only to the engine type, but to each engine at the factory. You could - if you were so inclined - take the flex plate and the new repop flywheel to a machine shop and have them match the flywheel to the original flex plate. Many would not bother with this, but a reputable AMC engine builder claims it's important (SC/397 on ifsja.org).

    Yes. Advertise the left-over parts on the part-out boards of ifsja.org and fsjnetwork.com The D60 is absolutely worth saving. If the BW1339 has a tight chain, somebody will want it. The TH400 would easily find a home too if you weren't so far away from everybody - you are in Alberta? There are several cities of Jasper. The front is a Dana 44HD, same as a generic 44 with heavier tubes. Supports the GVWR of these trucks. Wheels and tires, sure.

    I'd like to see pics. The sheet metal might still have some value. Front fenders are desirable if they can be straightened - or even just the flares straightened. The bed likely has some value if it's not rusty. Again, flares are the prime parts.
     
  9. Apr 26, 2020
    Ol Fogie

    Ol Fogie 74 cj5 304, 1943 mb

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    Tim, Thank you, I am working most of this coming week but will try to get time to go by there and clean out around the truck. Will take some pic and post them for you. I will see if I can see the casting # on the block as well. Oh btw I am actually in Georgia near Atlanta.
     
  10. Apr 29, 2020
    Keys5a

    Keys5a Sponsor

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    What Tim says cannot be stressed too much. The 401 is very desirable in certain circles, and they are getting harder to find. Verify that it has the "401" cast just above the oil pan rail. Many got swapped out. Also check if it has antifreeze. It gets cold enough up your way to have a block with water freeze and crack the block. An old friend had two cracked 401's and just couldn't bring himself to scrap them.
    -Donny
     
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  11. Apr 30, 2020
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

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    Also mentioning - a 401 crank in a 30-over 360 block is 391 cid. 60 over is a 396.
     
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  12. May 1, 2020
    fhoehle

    fhoehle Sponsor

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    If it is a genuine 401, and in good enough shape for a rebuild sans sleeves, you have a great find on your hands. The few I have seen did all run a bit warm, but all of them were incredible performers, probably a bit much for the CJs they were put in. A good mechanical fixed fan and shroud along with a good radiator will go a long way towards being cool. Don't go crazy on cam choice and keep compression reasonable so gasoline choice is not an issue.
     
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  13. May 1, 2020
    Ol Fogie

    Ol Fogie 74 cj5 304, 1943 mb

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    Been working full time this week. I will try to get time this weekend to check it out. my first impression was it is probably a 360. after research it the vin #says its a 401. All looks factory, with all the acessories attached. I plan to see if it will turn over and not stuck. and see if it has any antifreeze present. My best guess is its been sitting there 10 or 12 years but the hood has been fully closed all that time. We will see. Will post more when I know more.
     
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  14. May 1, 2020
    aallison

    aallison 74 cj6, 76 cj5. Has anyone seen my screwdriver?

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    either would make a fine motor. and to be honest, you could not really tell much of a difference unless you really got on the gas.
     
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  15. May 3, 2020
    Keys5a

    Keys5a Sponsor

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    The torque difference between a 360 and a 401 is night and day. You will know the difference in performance immediately. Thats why 401's have such a following.
    -Donny
     
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  16. May 5, 2020
    Ol Fogie

    Ol Fogie 74 cj5 304, 1943 mb

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    IMG_1024.JPG Well I returned to check out the J-20 pu. today. Cleared away the brush and briers,raised the hood. So much much leaves ,sticks, and trash had been carried in there by squirrels and pack rats all that was visible was the air cleaner.
    Cleaned out the debris and sure enough it's an AMC 401. See the casting # on the drivers side of the block. Oil level full on dip stick and very clean as if it had just been changed, no moisture or rust present. No coolant visible in top of radiator,however I drained some from the radiator drain into a bucket. It looked like new antifreeze, very clear not rusty or dirty. My 5 ball tester said it was good to -25 degrees, plenty good for this area. Put a socket wrench on the crank pulley nut and the engine turned easily and smoothly.:clap:Found the instrument cluster it showed 88k miles. Judging from other wear factors I would guess that is the original miles. The truck was supposedly a daily driver and had no problems at the time of accident.
    The body is almost all unusable from the accident. the only thing not damaged is the grill and the left front fender flare. Both axles are intact(ratio unknown). At first I thought it was a Quadratrac but it is an automatic with a d20. There is a factory T- handle under the dash that says low-range on it.
    Opinions please, how much do you all think I should offer him for the complete truck? I would be taking a risk that the engine has hidden problems or is not usable or rebuild-able.
     
    Last edited: May 5, 2020
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  17. May 5, 2020
    Ol Fogie

    Ol Fogie 74 cj5 304, 1943 mb

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    more photos.
     

    Attached Files:

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  18. May 6, 2020
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

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    Ok, it's definitely a 401. I'm a little puzzled by the "T-handle" comment though. It could be a D20... here's a Dana 20 shifter in my J10:

    J10Dana20.jpg

    The first years Quadratracs used a cable shifter with a T-handle for low range. They had the vacuum-operated e-drive switch in the glove box.

    No pictures of the body? Nice razor grille, no dents, worth some money ($50? $100?).

    Original Motorcraft 4300 4V carb. Not bad if the top isn't warped. Has an oddball base pattern.

    Only ratio available with this combo this year is 3.73:1.

    Regarding price, how much do you want it? I'd say minimum price is scrap value. GVWR of a J20 is 7000-8000 lbs, so you could guess that there's 4000-5000 lbs of unprepared scrap there. I'd guess the most you'd get is $150/ton, so no more than $375 for the carcass. Twice that is $750, which I'd be very pleased with. You could get that back if you can haul it out, break it down and sell off the pieces. If you set the first price, I'd mention the scrap price story and say you'll drag it away and leave the site clean. If he names the first price, I'd be very pleased to get ti down to ca $750. If he starts with an astronomical price, talk about can't hear it run, all the value over scrap is in the engine, how much work to get it out of there and running, you can get similar power and much better economy with an LS Chevy, etc. Looks like the engine will be ok, but you'll have to decide how much you want it and how willing you are to break it down and market the parts.
     
    Last edited: May 6, 2020
  19. May 6, 2020
    Glenn

    Glenn Kinda grumpy old man Staff Member

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    The drive flanges on the front axle would make me think Quadratrac.
     
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  20. May 6, 2020
    ITLKSEZ

    ITLKSEZ Hope for the best, prepare for the worst

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    I agree. Check for an offset full float D60 rear.
     
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