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  #1  
Old 09-11-2006, 02:01 PM
Blake Blake is offline
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Swap a 401 from a 360

I recently lost my 360 due to it locking up tight while I was driving.

I've found an AMC 401 that I may buy and swap in place of the locked up 360.

I know that I will need a new flex plate due to the 401 being externally balanced.

What else will I need?

I'm hoping that the 401 will bolt up to my existing exhaust, motor mounts, etc. Is the external dimensions of the 401 the same as the 360?
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  #2  
Old 09-11-2006, 02:06 PM
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derf derf is offline
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Externally, there is little or no difference between the 304/360/401 engines.

You will need a specific flexplate and need to balance it. All AMC engines are externally balanced.

Everything else should bolt up or be close enough.
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  #3  
Old 09-11-2006, 02:08 PM
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mdill mdill is offline
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Flex plate from a AMC car, (75 Madador or some such )
Assuming the 401 came from a mid 70's FSJ , you need to pull the TH400
bushing from the crank snout.
Harmonic ballancer from the 401.
Some accessory bolt holes will be one size larger (exhaust manifold outters, Alt pivot bolt ..)

That is about it.

Mike D.
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  #4  
Old 09-11-2006, 02:09 PM
82Waggy 82Waggy is offline
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If you are going to run the Torqueflite tranny you will need to get a Flexplate designed to adapt it to the 401 and may need to remove a bushing from the crank so that the torque converter will mate up.
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  #5  
Old 09-11-2006, 02:12 PM
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fulsizjeep fulsizjeep is offline
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This is a tech tip from CFSJA site:
http://cfsja.org/tech/drivetrain/401/401.html

If the 401 is from an earlier NON FSJ AMC vehicle, you want to check and see if it is a 3 bolt or 4 bolt crank pulley. The 3 bolt is a hassle to find a pulley for your Jeep accessories. Wille had some issues with that when he got his 401 from a AMC car project for his Waggy...
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  #6  
Old 09-11-2006, 02:13 PM
Blake Blake is offline
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I'm swapping the 401 into my '83 waggy that has the 306/727/229 combo.

Did the waggys have the 401 as an option? If so, can I just go to the parts store and ask for a flex plate from an '83 waggy with the 727 and 401?
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  #7  
Old 09-11-2006, 02:15 PM
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fulsizjeep fulsizjeep is offline
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NO, you want a 401 to 727 flexplate for a 1974 Matador.
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  #8  
Old 09-11-2006, 02:28 PM
Blake Blake is offline
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Quote:
Originally Posted by fulsizjeep
NO, you want a 401 to 727 flexplate for a 1974 Matador.

What the heck is a Matador? What made that?
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  #9  
Old 09-11-2006, 02:33 PM
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fulsizjeep fulsizjeep is offline
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Wow, you must have been born after 1974? (sorry, just had to bust yer chops) It is an AMC, the mother company that made it possible for Jeeps to get a 401 to begin with. Preceded by the name Rambler.
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  #10  
Old 09-11-2006, 02:35 PM
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mdill mdill is offline
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Madador is a AMC car.
Jeep never put a 401 in front of a 727, but AMC did, hence the need for a
AMC not Jeep Flexplate. The crank will have a bushing in the snout (hard to see) if the 401 came from a FSJ. The bushing is there to locate the TH400 torque converter, but if left in will distroy your 727 and maybe the thrust bearing in the 401 before you start the engine.

Jeep offered the 401 from 72(??) -> 1978 in one configuration 401/TH400/Q-trak.

Mike D.

Last edited by mdill : 09-11-2006 at 02:49 PM.
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  #11  
Old 09-11-2006, 03:11 PM
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fulsizjeep fulsizjeep is offline
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Quote:
Originally Posted by mdill
Jeep offered the 401 from 72(??) -> 1978 in one configuration 401/TH400/Q-trak.

74-78
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  #12  
Old 09-11-2006, 05:29 PM
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Millerluck Millerluck is offline
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You will also need to get a starter for a 74 Matador with a 401. The old starter won't reach the gear on the new flex plate.

I orderd my flex plate from these guys.

http://www.partsamerica.com/ProductDetail.aspx?mfrcode=PIO&mfrpartnumber=FRA30 5&parttype=267&ptset=A


And a solenoid for the new stater, plus do a little easy re-wire for the positive battery cable.

Larry
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Last edited by Millerluck : 09-11-2006 at 05:37 PM.
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  #13  
Old 09-12-2006, 06:11 AM
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Elliott Elliott is offline
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Quote:
Originally Posted by Millerluck
You will also need to get a starter for a 74 Matador with a 401. The old starter won't reach the gear on the new flex plate.

If he has the starter from the '83 360 he's pulling that's going to work isn't it? I don't recall having to swap the starter out on my '80 Cherokee when mating a 401 to 727.
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  #14  
Old 09-12-2006, 06:25 AM
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Crazy_Jeepman Crazy_Jeepman is offline
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Quote:
Originally Posted by Elliott
If he has the starter from the '83 360 he's pulling that's going to work isn't it? I don't recall having to swap the starter out on my '80 Cherokee when mating a 401 to 727.

Yes it will, only swapping into the rigs with the Mitsu style starter would you have to go though what Larry (Millerluck) had to do.
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  #15  
Old 09-12-2006, 06:56 AM
lookin4jeep lookin4jeep is offline
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Here is link to a web page, go to the "tech tips" section. It has good information on this.

http://www.cfsja.org/
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  #16  
Old 09-12-2006, 08:15 AM
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will e will e is offline
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I just completed this swap. The engine I had was from a 73 Javalin (also an AMC)

This particular swap presented a problem due to the front crank pulley having only 3 holes and 2 grooves. My 81 had 4 holes and 3 grooves. I was never able to locate a 3 hole 3 groove pulley and finally had bulltear custom make one for me. It works great. It was under $200 but I don't remember the exact price.

The stuff they have told you makes it sound like a lot of work but it isn't too bad. I didn't have to deal with the thrust washer or flexplate, my motor came with these.

The exhaust manifold bolts on the 81 were two different sizes, on the 401 all of the bolts were the same size as the larger 81 bolts. I didn't have to do anything to the manifold itself. I just went and bought some stainless steel bolts.

The alternator pivot hole is a larger thread. I bought a larger bolt.

And the one thing no one has mentioned yet (and may not be a problem for you) is I had to use the oil pan from my 81. The two pans both bolt up to either engine HOWEVER (and but this would have been good to know before I installed the motor ), the 81 has a driver side axles gears. Jeep had to reroute the exhaust to clear the front drive shaft and, as a result, ended up changing the oil pan to clear the exhaust. It is just a small 'dent' and you hardly notice it looking at it but, believe me, it's important.

My 81 starter bolted right up.

Lets review:

Starter/wiring (if you have the Mitsu starter)
Flexplate/bushing removal (regardless of donor engine)
Exhaust Bolts (Probably but I heard some have the smaller size too)
Oil Pan (Almost certainly will have to swap in the one from your 83 if it is driver drop)
Alternator bolt (Probably but I heard some have the smaller size too)
Crank Pulley. (If you have the 4 bolt balancer you will be in good shape to use your 4 bolt 3 groove from your 83, if not, you might need to get a custom pulley made)


Exhaust, intake, accessories all fit on the 401. Motor mounts are the same.

Oh, before you buy the 401, take a look at the underside of the block, right where the motor mounts attach (on either side) should be a BIG old 401. If it says 390, 360 or 304 then it is not a 401. Don't buy a 390, it will not easily swap.

Good luck, PM me if you have any questions
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Last edited by will e : 09-12-2006 at 03:16 PM.
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