360 to 401 w/questions

[brent]

Got 60K on a rebuild right now, figure she's good for another 60. I'm just thinking way down the road.
Fundamental differences in swap? Of parts?
Also, I see a lot of internet engine rebuild shops selling AMC 360's and 401's between 1200 and 1400 bucks. Are these places to be trusted?
Getting way ahead of myself, Brent

[Rande]

Flexplate or flywheel is the big issue. Balance is different between the two engines.

[illegalFSJ]

360 is internally balanced while the 401 is externally balanced. So you'll need a 401 block with the 401 specific harmonic balancer and flexplate/flywheel.
360 heads are the same as the 401, so those swap. Other than the balance issue, it's a bolt-in smile.gif

[bigun]

can you use 401 internals crank,rods,and use a 360 block the reson I ask is I know where there is a 401 with a cracked block and I happen to have a spare 360

[ August 10, 2003, 09:22 PM: Message edited by: bigun ]

[Al Johnson]

Originally posted by bigun:
can you use 401 internals crank,rods,and use a 360 block the reson I ask is I know where there is a 401 with a cracked block and I happen to have a spare 360"Anything" is possible, but some things aren't worth the trouble. This is one of those.

[bigun]

Ok I'll just have to talk my way into the dogleg heads

[Hammer]

The only AMC engine internally balanced is the 258 that I know of (that shares swap able parts with the V8s). All other V8s are externally balanced.

As for swapping the 401 rotating assembly in the 360 block. Don't waste your money! It works great, but you can spend less money on a very solid motor. Trust me there ;)

[Wesdog]

Originally posted by illegalFSJ:
360 is internally balanced while the 401 is externally balanced... Are you saying the flexplate/flywheel and dampner for a 360 are all neutral in balance? If the 360 is internally balanced then that's what I'd expect. I've never heard that about a 360 before and it surprises me if it is true. Can you confirm this. My 77 has a 360 in it and the dampner doesn't look neutral to me. What am I missing?

Edit: Nevermind, I just read Hammer's post above and it confirmed my understanding of the AMC V8's balancing, they are all externally balanced in stock form.
Wesdog

http://www.fullsizejeeps.com/jeeps/files/Misc-Pictures/wesdog_avitar1.jpg

[ August 11, 2003, 08:04 AM: Message edited by: Wesdog ]

[Wesdog]

Just to stir the pot a little here's an email I got a couple years ago from Dick Dotson after buying his AMC books and asking him some questions:

****************************
Wes,

Thanks for the positive comments on ebay. I can appreciate your surprise at
seeing the material. It is different in more ways than is immediately
apparent. I should point out that I edited AMC and Jeep newsletters for
nearly 2 decades though I am originally a Studebaker racer/mechanic and
editor. I'm also a long time outdoor/Jeep man and subscribe to several Jeep
groups though I don't follow them very close for obvious reasons. After
watching my own AMC/Jeep letters section and various articles for this long
with my peculiar background, I would never use an AMC 390/401 in any extreme
duty circumstances.

The problems lie in the extremely thin 390/401 cylinder walls with a standard
bore. The situation gets worse as the bore size increases--which is
unavoidable due to ever higher miles and wear. This in turn produces a lot of
wall flexing if higher compressions or super/turbocharger boosts are used,
and of course gasket blowing (note the article on adding head bolts to AMC
V-8s) and cylinder cracking that goes with these conditions. The next time
you build a motor I would suggest that you find a 360 AMC block and install
your 401 crank in it. That's an unusually good motor for its size. (About 385
cid). My favorite among the AMCs is using the 401 crank in the 304 block
(about 325 cid) which gives bearing areas and wall thickness specs few motors
have ever had. We Studebaker people have always been extremely reliability
conscience, which is why we do so well in record breaking at Bonneville and
are able to run such high boosts. Few outside our circle are as keen on the
subject or reliability (no complaint from us).

Low boost supercharging will produce more horsepower from a 360/385 AMC than
anyone could hope for in the most expensive built 401s -- and live to a ripe
old age even in the harshest of circumstances. Unfortunately no such
supercharger is currently available from the industry (less desirable for
off-road turbos do our testing of course). That is what you see us developing
and is the reason you are receiving our technical newsletter. By the end of
this year we'll have at least several larger superchargers in operation to
demonstrate. This is about increasing low rpm torque rather than high rpm
horsepower. 830 lb.ft of torque from a record setting 300 cid Bonneville
Studebaker proves that reliability and low rpm performance can go together.
No current Studebaker drag or top speed car operates over 6000 rpm. That
would get us laughed off most newsgroups now wouldn't it? A very old rule in
racing I learned the hard way in my first serious motorcycle race 50 years
ago -- "you have to finish to win". The same goes for any serious outback
venture. Dick
**************************************

Wesdog

http://www.fullsizejeeps.com/jeeps/files/Misc-Pictures/wesdog_avitar1.jpg

[ August 11, 2003, 08:21 AM: Message edited by: Wesdog ]

[Hammer]

The 304 block can be seriously over bored if done right.
The 360 can do very well with the larger overbore and still run fine.
I agree on the thin walls for 390/401s. Old school of thought is to use block hardener to stiffen up the walls, especially when they are overbored. Sleeving can work well if done properly.
But of course we can now get new engine blocks, so that should solve those problems (if they were truly made right!).
Btw, I created my engine without the help of the internet some years back. 360 block .045" over, 401 crank indexed out to 3.75" stroke. 360 rods small end bushed for full floating pins. And SBC 400 pistons with a lot of custom work done.
Comes out to a 401 CID motor, but 4.125" bore x 3.75" stroke. Works great, even when it sees above 6,000 rpm all the time.
Always thought a supercharged stroked 304 block would be an awesome combo. But never had that money to spend.