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  • 401 differences

    are there any differences between the jeep 401s and the amc 401s? I've got a lead on a 401 from a javelin, would like to put it in my 89 waggy.....

  • #2
    AMC changed the crank snout in ~72 to the new style on all engines.
    So pre that time you need to buy/machine (from where ??) a crank adapter.

    Mike D.
    -----------------------------------------
    Home of ADHD project list

    1977 J-10 Honcho 360-T15-D20
    1977 Cherokee WT 360-Th400-NP241 true-trac(s)
    1979 Cherokee 4 Door 258-T-18-D20
    1981 Cherokee Chief WT 360-727-NP208
    1972 K20 Suburban 350 SM465 205
    And the other stuff that gets driven
    ----------------------------------------

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    • #3
      If the 401 from the javelin is a true 401 Javelin, grab the car and sell it. It'll finance your FSJ project. Oh and send me the tranny out of it!
      "I'm sick of this sickness, don't touch me you'll get this."
      1984 GWag "orphan" for sale
      2 x 1975 Matador "murder machines"
      1970 SST390 Javelin 10 yr project!

      Comment


      • #4
        coondawg how in the heck did you find a 401 in new hampshire?!?!?!
        1982 J-10 Pioneer

        Check out my YouTube Channel !!
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        2018 Grand Cherokee Upland

        "The J-series Jeep pickups are simultaneously the ugliest and the most beautiful trucks ever made."

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        • #5
          Well, It's just the motor, and its down south, where my waggy is....

          Comment


          • #6
            i don't think the 401 ever had the old crank flange.wasn't it '70 when that changed?
            Originally posted by Hankrod
            Ristows right.................again,


            Originally posted by Fasts79Chief
            ... like the little 'you know what's' that you are.


            Originally posted by Fasts79Chief
            I LOVE how Ristow has stolen my comment about him ... "Quoted" it ... and made himself famous for being an ***hole to people. Hahahahahahahahahha!
            → Where the kids hang out...

            fsjbuilder.org come for the mindless chat,stay for the hand drawn emoticons.

            It's like you're unraveling a big cable-knit sweater that someone keeps knitting...and knitting...and knitting...and knitting...

            Comment


            • #7
              Guy says its out of a 73 or 74, so I think it will be fine....

              Comment


              • #8
                73/74 not enough of a difference to bother you.

                buy that baby stuff a decent cam in there.

                like .480 or more lift (they love .500) and at least a 270 adv dur with a 218-226 dur @.050 will yield a nice rpm range right into the mid 4000s and low 5ks and a 112 lobe sep will give you decent idle. you may never need the rpm but why not have it if you ever want it, the bigger cams dont rob you of much if any low end on a 401 so take advantage of it. performer intake and holley 670 with an hei and you'll be rockin
                Cherokee S Chief Widetrack W/ Cummins 4bta Diesel, 91 dodge intercooler, hy35/9, AC NV4500/D300 3.54's Ploks 4" BJ's w/ 33's, scout 33 gal fuel tank ( Sold, to a good fsj home)
                The 608.9 hybrid dana 44 build

                AMC 401 supporter

                GO UM Montana Griz

                "Dont worry the Coors light engineering department will be documenting this accordingly."

                Comment


                • #9
                  Originally posted by Ristow
                  i don't think the 401 ever had the old crank flange.wasn't it '70 when that changed?
                  If my memory is correct, 70 is when AMC changed the deck height, and the 343->360 2??->304 but the 390 stayed for one year, then I think it was 72 the crank flange changed, but that is from memory.

                  Mike D.
                  -----------------------------------------
                  Home of ADHD project list

                  1977 J-10 Honcho 360-T15-D20
                  1977 Cherokee WT 360-Th400-NP241 true-trac(s)
                  1979 Cherokee 4 Door 258-T-18-D20
                  1981 Cherokee Chief WT 360-727-NP208
                  1972 K20 Suburban 350 SM465 205
                  And the other stuff that gets driven
                  ----------------------------------------

                  Comment


                  • #10
                    yeah,sounds about right now that you say it,i can't remember either.
                    Originally posted by Hankrod
                    Ristows right.................again,


                    Originally posted by Fasts79Chief
                    ... like the little 'you know what's' that you are.


                    Originally posted by Fasts79Chief
                    I LOVE how Ristow has stolen my comment about him ... "Quoted" it ... and made himself famous for being an ***hole to people. Hahahahahahahahahha!
                    → Where the kids hang out...

                    fsjbuilder.org come for the mindless chat,stay for the hand drawn emoticons.

                    It's like you're unraveling a big cable-knit sweater that someone keeps knitting...and knitting...and knitting...and knitting...

                    Comment


                    • #11
                      Was it really the crank flange or was it the harmonic balancer that was different including 3 holes for the pulleys instead of 4 on the newer ones? Will e has an old style 401 in his Waggy. He got a aluminum pulley for the Waggy belt system from BullTear right?
                      Flint
                      Ran when parked.
                      http://jubileejeeps.org/quadratrac
                      88 GW, 401/727/208, 5" lift, D44s/4.10s/locked up, 35s with a few Evil Twin & TT's Fabworks mods
                      76 401 Wag, 77 401 Wag, 77 401 J20
                      http://eviltwinfab.com http://www.ttsfabworks.com

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                      • #12
                        the flange was changed,when the t/c 727 replaced the b/w automatics.
                        Originally posted by Hankrod
                        Ristows right.................again,


                        Originally posted by Fasts79Chief
                        ... like the little 'you know what's' that you are.


                        Originally posted by Fasts79Chief
                        I LOVE how Ristow has stolen my comment about him ... "Quoted" it ... and made himself famous for being an ***hole to people. Hahahahahahahahahha!
                        → Where the kids hang out...

                        fsjbuilder.org come for the mindless chat,stay for the hand drawn emoticons.

                        It's like you're unraveling a big cable-knit sweater that someone keeps knitting...and knitting...and knitting...and knitting...

                        Comment


                        • #13
                          I've got the summiit 8600 on my 360 now, barely been ran. Should I go a step up with the cam?

                          Comment


                          • #14
                            Heres a cut and paste of something i posted awhile back. the 8600 is a great cam but if its in a good running motor i wouldnt rob it. its nice having a spare motor even if it is loose just in case things go ary heres some numbers thatmay or may not help you. most of these motors were fresh so the rings were just seating up and tuning wise we didnt do much tuning on the dyno. definately they all picked up a little more power after being dropped into the rigs and tuned on over the next few days and weeks


                            i have engine dyno print outs that show exactly what i am describing that the 401 will produce the same amount of power (or close to within 10-20 hp or ft/lbs) at 1500-3500 rpm just like the 256 and the 260 but with a much bigger cam and with the bigger cam and right duration you can gain from larger peak torque and hp, as well as a broader operating range. giving you more power when you want it and more rpms when you are glad to have them.


                            Ran a HMV 272 and it worked very well in my old 401. I ran 9.5 forged pistons with '73 model heads and the motor made awsome power- on the order of about 371 hp and about 483 ft/lbs.

                            It would also rev to about 6,500 rpm. There was a little chop in the idle, but nothing annoying or difficult to tune. I ran this motor with both an automatic tranny and a manual tranny, and it worked well with both set-ups.

                            all of these had fair compression ratios that said my buddy took a stock bore 401 with 150k miles honed it polished the crank put std bearings and the stock pistons with new cast rings a howards .479/.479 292/292 adv dur 222/222 dur @ .050 114 lobe sep cam in with stock bridged heads a holley 600 and a torquer intake with 1 3/4 tube headers and that thing runs circles around alot of 401's ive seen built.. alot can be said for careful tuning and getting lucky too.

                            AMC 401 .030" Over
                            Bore: 4.195"
                            Stroke: 3.68"
                            Compression: 9.6:1
                            AMC 502 Heads Stock 2.025" 1.68" Valves
                            670 CFM Carb
                            Dual Plane performer
                            Small Tube Headers w/ Mufflers
                            PAW version of the summit K8601 Cam

                            RPM HP TQ
                            2000 156 405
                            2500 198 416
                            3000 241 422
                            3500 295 431
                            4000 341 453
                            4500 360 432
                            5000 351 371
                            5500 336 330
                            6000 302 274

                            _________________

                            401 .030" Over
                            Bore: 4.195"
                            Stroke: 3.68"
                            AMC 6090 Heads mildly ported 2.025" 1.68" Valves
                            800 CFM Carb
                            Dual Plane Intake - airgap
                            large Tube Headers 1-3/4"tube w/ Mufflers
                            crower solid 292 cam
                            CR 10.5:1

                            RPM HP TQ
                            2000 161 413
                            2500 210 432
                            3000 259 441
                            3500 314 462
                            4000 365 469
                            4500 400 475
                            5000 429 451
                            5500 439 412
                            6000 420 367



                            same as above but with a single plane torquer intake and a little more tuning/ timing..... couple of factors could have influenced this run that day it was about 10 years ago.

                            RPM HP TQ
                            2000 153 387
                            2500 207 426
                            3000 260 448
                            3500 318 473
                            4000 359 491
                            4500 421 498
                            5000 468 496
                            5500 486 468
                            6000 472 429

                            401 w/ stock bore and stock heads, 9.5:1 comp, air gap dual
                            plane intake, 650 cfm TBI, and small tube headers. comp 260h cam and the Crower 276HDP
                            >

                            comp 260h
                            >
                            >RPM HP TQ
                            >2000 169 387
                            >2500 210 398
                            >3000 236 412
                            >3500 271 433
                            >4000 319 397
                            >4500 292 354
                            >5000 271 307
                            >5500 246 268
                            >6000 231 202
                            >

                            Air gap matched to a holley 770
                            >Crower 276HDP
                            >
                            >RPM HP TQ
                            >2000 166 427
                            >2500 210 442
                            >3000 259 453
                            >3500 310 465
                            >4000 339 445
                            >4500 331 386
                            >5000 328 344
                            >5500 311 297
                            >6000 279 244



                            401 9.8:1
                            R4B 750 Holley
                            Mildly ported 090 heads
                            .500/.512
                            222/226
                            270/274
                            112 lobe sep

                            We should have spent more time tuning on this one but back then time on the dyno was spendy. when tuning on it in the rig it picked up a fair amount more on the top end with some recurving of the dist and larger secondaries In all honesty after a few months if i had taken this motor out and re run it i think it would have come close to 400hp


                            RPM HP TQ
                            2000 178 418
                            2500 214 427
                            3000 251 449
                            3500 301 478
                            4000 346 489
                            4500 369 443
                            5000 347 381
                            5500 316 338
                            6000 279 284



                            rarely does my motor see over 5k but having it pull hard right up into 4500-4800 rpm range when passing is right on the money. the 401 because of its large bore and stroke is a very versitile motor and is often under built.

                            pick and choose carefully. remember my ability to tune or inability to tune on the engine dyno impacted these numbers also the solid cam numbers are from a friends motor

                            Food for thought
                            Cherokee S Chief Widetrack W/ Cummins 4bta Diesel, 91 dodge intercooler, hy35/9, AC NV4500/D300 3.54's Ploks 4" BJ's w/ 33's, scout 33 gal fuel tank ( Sold, to a good fsj home)
                            The 608.9 hybrid dana 44 build

                            AMC 401 supporter

                            GO UM Montana Griz

                            "Dont worry the Coors light engineering department will be documenting this accordingly."

                            Comment


                            • #15
                              Having compression to match the duration of the cam and gears to get you into the correct rpm range are the key.

                              If staying with stock compression and/or stock gears (2.73 to 3.31's), you probably will not obtain results similar to Dusty's (he was running 9.5 -10.5:1cr in those examples and some pretty high gear ratios as I recall).

                              A Comp XE256H10 dyno'd over 400ftlbs from 2000-4400rpm, 428ftlbs at 3400rpm, 200hp at 2500 and 348hp at 4800rpm with 9:1cr, a Holley 670 and Edelbrock performer manifold.

                              So as you can see, long cams are not necessarily the holy grail of making power.

                              Figure out what your useful RPM range is and cam/gear accordingly.
                              Last edited by 82Waggy; 06-17-2007, 07:04 AM.
                              '82 Wagoneer, 727, NP208, Lockouts, Rhino - Now undergoing frame off resto
                              Currently building 401 MPEFI, 9.3 CR w/KB354 Pistons, Thorley Tri-Y's, Roller Rockers, Port Matched & Polished 65cc Chamber Stock Heads.
                              Also bare tub restoring 69 BBB Javelin SST Go/Mod Pak 390 - Why build one when you can build two at twice the price!!

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