401 differences

[will e]

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.....

I picked up a rebuilt 401 and went to put it into my 81 waggy that had a 360. Here are the things you might find.

1. Flexplate. My purchase came with the correct flexplate. BTW, this only bolts to the torque converter in 1 position (4 are possible). They all look close but you will not find out for sure until you go to put the last 2 bolts in. Mark this before you start or just be prepared to turn the torque coverter a few times.

2. Oil pan was different, driver side drive shaft caused the exhaust to be rerouted after a certain year. 81's included. These pans have a very slight dent in them that allows them to clear the rerouted exhaust. I just swapped it with the one from the 81 no problem (excpet I discovered this after putting the engine in the truck)
3. Alternator bolt is larger. I didn't have one so I went and got one. No big deal.

4. Exhaust manifold bolts are larger. (Same size as the two middle bolts on my 81 head)


Starter, tranny, tranny linkage, etc all bolted right into place. Motor mounts, water pump, etc were all good too.

Now for the harmonic Balancer/Crank pulley.

The one from my 401 ('71 javelin) had 3 holts for the crank pulley. My 81' had 4 bolts. This means I could not bolt my crank pulley onto the HB attached to the engine (and you can't swap them out).
This was only a problem because the 81' had 3 grooves and the 3 bolt ones ALL have 2 grooves.
This became a problem because I run AC/PS and a CS140.
I tried a lot of different belts path's and combos but in the end I ended up needing to run the original two parallel belts from crank/alternator/AC/WP combo with the third belt going to the PS pump.

I tried an adapter that allows you to add a third pully but the other problem I had was the 2 goove 3 bolt pully's do not have the same diameter for both grooves. Running these in parallel did not work since one was always slipping.

In the end I had the folks at bull tear make me a pulley for the crank. It wasn't expensive (less than $200 if I remember correctly) and it works great. If you decide to go this route, let me know and I can help you work with Bull Tear since it was a custom job.


If you are not planning on AC I don't think you will have this problem at all and can probably get away with 2 grooves.

If I recall anything else I will let you know.

[Ristow]

just get a new damper.

http://cgi.ebay.com/ebaymotors/AMC-304-360-401-balancer-damper-steel-SFI-10-000rpm-f9c_W0QQitemZ320127633373QQihZ011QQcategoryZ33616QQrdZ1QQcmdZViewItem

[Coondawg]

I plan on using my heads from the 360 on the 401, since they are already rebuilt. I have an edelbrock performer manifold and 1406 carb that I'm gonna put on it.
Have 140 amp alternator on it. Electric fan, rebuilt 727 with some goodies.
Exhaust has been comepletely redone due to Dana 300. Dual in/dual out dynomax muffler.
Dana 60 with 4.11s going in the back, chevy dana 44 going up front.
35x12.50s to top it off.......