AMC 401 build-up, anybody?

The last time I built an AMC 401 was close to 30 yrs ago but man it was an awesome piece.

My best bud is building a jeep CJ-7 and we're looking to do a 401 build-up along the following lines:

A good basic (broad torque 2500-5500) combo would be:

9.5:1 shortblock, +.030 bore, square decked, line honed, deck plate honed (if we can borrow/locate one for an AMC)
Edelbrock performer RPM intake, port matched to heads
Bowl ported Edelbrock heads, Serdi Valve job, install hardened locks (Edelbrock OEM is pretty skimpy)
All oil passages in block and crank chamfered, the 'priority mains' mod would be good
Deep sump pan with ported stock volume pump
Hydraulic Flat tappet Cam in the 232/237 @.050 range and /.510-ish lift on 108 installed +4 at 104 ICL
1 3/4" x 3" Headers
MSD 6AL or other good ignition
Re-curved distributor with ~12-14 degrees initial and (limited to) 20-22 of centrifugal.
good radiator

Should make about 470-480hp with a bunch of mid range torque, peak power around 5200 redline 5800-6000


thoughts?

I was an AMC fan before I went Mopar( back in the 80's).
The AMC v-8 can make enough power to surprise a lot of people. Sounds like a nice build! At least you can buy decent parts for them now. I would probably look into a cam with 904 specific lobes since its not a high rpm build. The extra lift with the Edelbrock heads should work well. Might make a little more power than you are hoping.
Keith

Im working on a 72 Hornet with a 401 and a T-10 right now at the shop. Blast to drive...Neat little car. I like it!

Good luck

MB

For a few more $$$ sb chevy rods and offset the crank . 421 cid
More torque and better idle.
The real problem is the cj springs .They are narrow and rap up real bad . Makes it a real chalenge to drive with a high torque engine.
Either way the 401 can make a lot of power any way you build it so have fun

I did that swap in 1980 to a '79 CJ5, what a torque monster that thing was everything was bolt in except exhaust....I built mine stock, used 1971 pistons for higher comp., ditched the Motorcrap carb for a Holley...

Indy has the stuff to build a 500 CI.

that Rambler is a neat little engine, except for the front cover oil pump

We've actually talked about the 421" using the chevy rods, more cubes with an even lighter bobweight but not sure the additional cost is warranted for what we're going for.

i find that 232/237 @ .050 on 108 +4 is a great all-around high-torque grind for naturally Torquey moderate RPM motors in the 400-420 range with a stick....gives it a nice big block type powerband with enough intake duration to pull to ~6000 along with a nice 'count-em off' idle. With a hydraulic flat tappet on these small-ish port motors it's almost as much of a concern to go too small on the intake lobe duration than too big.

Should be fun little project, been a while since I worked on one. Ever notice how much an AMC resmembles a Buick? It's not coincidence if you read a bit into the history of Nash-Rambler/AMC.

sounds like a cool project, more aftermarket choices nowadays than 33 years ago, wish we had those options back then, esp. w/AMC...

In the early 90's I had a friend that had a stock 401 in a jeep and it was a torque monster,It seemed like the tach would stop at 5,000 rpm but it was plenty

Thanks guys, yeah this should be a really fun build. As die hard Mopar as I am I really enjoy wrenching something different every now and again

growing up in jersey as a small kid..my neighbor was an amx guy...4spd...i used to watch him tune it up on weekends..dont know what engine it was..but it ran low tens back in 79. he used to drag race it at atco...

I was just considering getting a 68 AMX 390 & checked out these guys after hearing about them on an AMC site.
http://www.bulltear.com/forums/showthread.php?18219-TWO-AMC-MOTOR-BUILD-EXAMPLES

Seems like the low deck 390 block with the offset ground 401 crank for 421" would be the best combo. Kind of like the AMC version of a 451 B motor.

but I guess 390 blocks are more rare than 401's

I've always thought Ramblers were cool thanks to my dad.. There used to be a mid-60s V8 Rogue running stock class around.. '66-'67 at Trails and Hyde Park that beat up on the other makes.

but getting back to 401s.. Just how hard is it to find a block now?

I hope your CJ guy has upgraded axles and driveshafts. The stock Dana 300 transfer case should handle it, tho.

Common stroke is 3.85 done with a stock crank, offset ground and .030 bore makes 426 inches, using a 401 block and crank. the 390 is shorter deck but only .033. Ro-DY will do crank as can shaft tech. use 6 inch small chevy rods at 2 or 2.1 and then custom pistons. For what you are doing it may be too much expense for 20 cubes as the stock crank and rods will do fine.

My car is 437 inches, indy heads.

Met an awesome AMC guru up in West Virginia today named Barry Allen. We're gonna do a 401 with a crank offset ground to 3.8" to use a 6" SBC rod and a 4.195"
Bore for about 420 cubes.

Barry is awesome, so knowledgable and yet so down to earth about his vast knowledge. He built a 439" Indy AMC that Dyno's over 1000 hp, it was sitting on the stand. He aslso has some incredible port work done to several sets of AMC iron heads.

OBTW, he had several other motors he was working his manic on, including the orange ones with the spark plugs going through the valve covers.

VERY COOL guy!

Quote:

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Met an awesome AMC guru up in West Virginia today named Barry Allen. We're gonna do a 401 with a crank offset ground to 3.8" to use a 6" SBC rod and a 4.195"
Bore for about 420 cubes.

Barry is awesome, so knowledgable and yet so down to earth about his vast knowledge. He built a 439" Indy AMC that Dyno's over 1000 hp, it was sitting on the stand. He aslso has some incredible port work done to several sets of AMC iron heads.

OBTW, he had several other motors he was working his manic on, including the orange ones with the spark plugs going through the valve covers.

VERY COOL guy!

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He built on for me...700hp with a big roller and dominator..