401 Vs 360

[la mula pescadora]

which engine will be better in over all perfomance, and torke power, easy to play with?

[J20 project]

La Mula, I've run probably 15 360's and was happy w/ all of them, however I always thought our Jeeps could use a bigger engine. I just built a 401 and dropped it into my J20 and it appears to have quite a bit more power and torque. Mileage is just as good or better. This could be just new vs old comparison though. I'm still tuning on it so the jury is still out but I think I will be very happy I stepped up to the 401. Of course I built it to about 300 hp. J20

[la mula pescadora]

i want to get a 401 bored it out open the heads and play with it but i dont know if i should keep the 360

[Jerk]

WOOO HOOO! Another 401 convert! welcome aboard brother, pass the collection plate! if we all converted to 401s, I bet d-c would start casting crate 401s for us jeep guys out here! that would be awesome. Jeez, I'm too stoked, I better cool off a minute..........................ok, 'snuff!
seriously, 401s are actually a better/ more dependable/robust engine than a 3dinky, I mean 60. you've got beefier main bearing webs, a forged steel crankshaft, forged steel connecting rods, (not cast iron like 3dinky/304s have.) and a lot more performance choices. I've read an article where a racing engine builder, this was in carcraft some years back, built a 10:1 cr 500hp 401 that ran on pump gas, it was a detuned version of a 12:1 (I think) engine similar to the one that ran in a Nevada open road race in a prepped AMX a few years ago, it won its class, I believe, with a 180 mph average speed and a 197 top speed...naturally aspirated! no nitrous or anything in an actual AMX not a fiberclone body/ steel-tube chassis race car, the website is around somewhere, I can't remember the link to the AMX article, anyway, most jeepers don't realize that over 200 speed records were set by Craig Breedlove in an AMX and Wally Booth who used to race in superstock (I believe) ran AMC's exclusively....ran in the 8 second range with no nitrous, blower! fun stuff, this was 20 to 30 years ago too. :D 401s are a kick! :D :D actually, if your going to mess with heads, use heads off a 360, they're essentially the same, but the exhaust manifold bolt holes are different on some, anyway I would reccomend just pocket porting and no polishing. resist the urge to enlarge the combustion chamber too, this will really drop your comp ratio and will only benefit you if you plan on sustained high rpm(5000 to 7000 rpm)... I know from 2nd hand experience here. friend of mine did it and had less power at lower rpm than a stock 401, but it raced vettes and won at higher rpm...this was in a cj7 with 35" boggers and 12" of lift BTW...NO $h1+ !!!! hell of an offroader too!

[ April 02, 2002: Message edited by: Matt W ]</p>

[la mula pescadora]

so 401

[linskej]

Ok I sold and I want one, 401. From what years and or cars/trucks can we find the mighty 401? Are any of the years better then the rest?

Thanks,
John

[Jerk]

Cars- rare 71 to 72/ maybe 73 javelins and such.

Trucks wags from 73/4 to 78, z engine code in these rigs. as in 6th or 7th digit in vin starting with j and then last digit for year(3 through 8)followed by a letter, can't remeber what means, then model number 45 and 46 ar jtruck for example, then either z or the next one is z, this is only in fsjs I don't have a clue as to what the cars' vin is. you should also visually check the sides of the block under motor mounts for a "401" cast in it.

[Kris]

<blockquote>quote:</font><hr>Originally posted by Matt W:
...similar to the one that ran in a Nevada open road race in a prepped AMX a few years ago, it won its class, I believe, with a 180 mph average speed and a 197 top speed...naturally aspirated! no nitrous or anything in an actual AMX not a fiberclone body/ steel-tube chassis race car, the website is around somewhere, I can't remember the link to the AMX article
<hr></blockquote>
It was not an AMX, It was a 70' "Mark Donohue" Javelin.
Here is the link...
192 in a Javelin (http://www.amcwc.com/192mph.html)
<blockquote>quote:</font><hr>
anyway, most jeepers don't realize that over 200 speed records were set by Craig Breedlove in an AMX and Wally Booth who used to race in superstock (I believe) ran AMC's exclusively....ran in the 8 second range with no nitrous, blower! fun stuff, this was 20 to 30 years ago too. :D 401s are a kick! :D
<hr></blockquote>
So were the 390's that these guys ran. ;)

kris. :D

[Don S]

My old Motor's manuals says 1971 AMC 330@5000 401
And the last was (AMC)a 1975-6 not rated Police Car 401 ....The last normal car was 1974 255&4600 Torque was 335@3200........ ;) ...ds..

[Rogue]

gotta say i love my 401, my ford driving buddy drove it with a slipping trans mission and a broken piston and said "that baby will move!!!" only problem for me has been trying to find pistons!!!, i also had a crankshaft problem which had to be welded and reground (thrust surface) but i could not find a replacement crank, so that would be the only downfall - unless you can afford high dollar pistons ( the forged pistons listed in everyone's catalogs ARE NOT AVAILIBLE) from some exotic manufacturer parts can be pretty hard to come by

[xj2fsj]

will a 401 bolt into a 360 bay? If the heads are the same then the exust manifolds should be the same. how 'bout the mounts and tranny?

[JeepFreak]

The 401 and 360 and 304 externally are the same so yes it will fit. The parts are getting harder to find for all AMC V8's and I would hate to pick up a used 401 that has already been bored. They are hard to cool when over bored so be careful when punching out a 401. As far as pistons go I am pretty sure that the 400 SBC pistons fit with a few mods.

[Jerk]

<blockquote>quote:</font><hr>Originally posted by Kris:

So were the 390's that these guys ran. ;)

kris. :D <hr></blockquote>

yeah, but they only made the 390 for 3 years- 68, 69, & 70, the 70 has a taller deck height -same as 401s, point being, it really frikkin hard to find a 70 390 that can be worked on, then you still have to use a 401 crank to get the 11 more cubes, plus no 390s bolted up to the th400 trannys that were so prolific in the wags, and jtrucks. thanks for the correction btw, I wish i could remember details better, dangit! :D

[Jerk]

<blockquote>quote:</font><hr>Originally posted by RogueStar:
( the forged pistons listed in everyone's catalogs ARE NOT AVAILIBLE) <hr></blockquote>

Whaaaa??????!!!!! say it ain't so!!!! I got another 401 to rebuild at +.040 bore, and I like forged plugs. Did they say why? or if they were on back order? who did you ask? This might be the biggest tragedy since opec's oil embargo!!!!! -Matt :(

[Hump]

I'm just backing Matt's question. I know of the inherent overheating risks, so I plan on only boring .010. Then you're telling me that a guy can't get forged pistons to put in it? Seems kind of ludicrious to rebuild and engine only to not bore it out and use the old pistons.

[Jerk]

hump, eventhough most AMC books say.022 overbore is max, you can appartently go +.060, like someone here did recently, I'm going + .040 since its already +.030 and there is some scoring on the cyl walls. I hope it cleans up at +.005 on each side!!!!! I hate to throw away a whole block, and just keep the rods/crank/heads.

[la mula pescadora]

i just call a local machine shopand for and for a 401 core is $ 100 and they don't have an engine kit for it everything is sold sepertly and he said it will come out aprox 700 no cam nor lifters will this be a fair price?

[JeepFreak]

You can still have the block sleaved if there is to much over bore. It won't hurt a thing to do this.

[Lindel]

Getting a once bored 401 sleeved is a very good option, and is worth the price. It gives you the option of going back to the stock size on pistons, and depending on the thickness and material of the sleeves, you can over bore the sleeves to .060, with no worries.

It also makes rebuilds that much easier, as it's easier to resleeve a block, than to rebore it. This is standard fair for diesels, and AA Fuel Dragsters, so don't be afraid of it.

[Jerk]

lindel - yeah, they charge bocou bucks to sleeve a block up hear in the "outer rim"! like they want $10.00 bucks a piece to install hard valve seats here, I think last time I asked the motor shop that did the machine work on my current 401 what they charge to sleave, it was like $80 bucks a hole!!!! that ain't cheap!!!!! this was 3 years ago too. ARRGH!

Mule- 100 bucks for a 401 block and nothing else seems kinda high to me, especially if its already been bored once, do you get crank and rods with it?

[la mula pescadora]

well i'm asuming that th core comes complete with pistons crank cam intake oil pan all the good stuf to rebuild it

[Jerk]

not bad! I think you should be able to get(if available in your area) a rebuilder 401 from a junkyard with everything still on it including valve covers, carb, waterpump, etc. for $250 or so. a running one pulled from a junk vehicle may go for $400 or more.

[Jeep Jeep]

Yes you can still get forged pistons from PAW. They are TRW pistons. I just purchase mine two weeks ago. The only down fall was that the smallest they make is a 030 over. I did not want to do that but I wanted forged pistons as I will be using the Cherokee to pull a camp trailer. PAW sell a rebuild kit minus the crank with forged piston for around $950.00. The pistons alone costs $ 611.00. I do wish some one made 401 cranks as mine had to be turned 20/20. Last time I can use this one. I'm getting fired up for this weekend as will be installing it. Hope to have pics soon. Then the body work starts. As far as 360 vs 401, I would say it what you intend on doing. Yes the 401 has more power but with the added expense of purchasing a 401, that is extra money you could spend on upgrades for the 360. Just my 2 cents.

[Hump]

Thanks for the clarification Jeep Jeep. So they do make forged pistons, but nobody makes cranks? I haven't done any real investigating, but it's a little disheartening. I am already trying to prepare for the amount of cost alone, and now I have to worry about just finding the parts to do it with.

As far as a core, I found a '75 wag in a local yard with a 401 that was missing the intake mani, and carb. They told me $50 for the block and anything else that happens to be attached in front of the tranny (heads, a/c, pumps...) I thought that was pretty good.

Question about what core means. Does that mean you give them a block, and they give you back a different one, or is that the one they do the machine work on?

[Jerk]

hump, not sure what core means, definately ask for clarification, they may use the term because it is vague and when you want more than what the want to give for that price , they can say" that ain't included in the core, that'$ ex$tra!) maybe not though, I'm a bit paranoid. :D 360 intakes will bolt right on, the only real difference between the 2 engines is in the block itself-crank,rods,mainwebs thicker. heads and all accessories will interchange. 401s never came with a 2 barrel intake however- NEVER! (prolly why that one is missing.) And no, I have never heard of anyone making replacement cranks for 401s, yet! ;)
jj- I too wish trw made +10 and +20 forged plugs. don't know why they don't. kinda dumb really.

[la mula pescadora]

is it possible for a 76 chero to have a 304 i think thats what i saw stampt on my block

[JeepFreak]

Yes it is very possible. Look at the vin number and that will tell you what it came with. If it is stamp 304 on the side of the block though that is 100% what it is.

[la mula pescadora]

defently a 304 well th headers will it be the same as one of 401