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AMC 401 Build Suggestions

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taplercj7 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote taplercj7 Quote  Post ReplyReply Direct Link To This Post Topic: AMC 401 Build Suggestions
    Posted: Apr/14/2012 at 3:54am
Okay, so here's the deal. This is my first engine rebuild and I just bought an AMC 401 tonight and the cylinders look beautiful! the only thing I'm not sure of is if it has been bored before. It doesn't look like it has but i really don't know what I'm looking for either. I paid $500 for the block, pistons, rods, stock cast intake, two oil pans for it, and two heads(one is cracked). I heard that i could have someone weld it, but not too sure of the practicality of that if i get this block where i want it. The only thing i could really see missing where a lot the miscellaneous little top end parts, and valve covers. So if anyone has some AMC valve covers they can part with let me know please. I currently have a 304 in the jeep running just fine, but i want this to be the ultimate upgrade! I'm wanting to run 40's eventually I think with Dana 60's and arb's. Also, looking for a AMC turbo 400 to mate to my new 401. need help here, Spicer 20 twin stick or Dana 300 twin stick?

Basically, just looking for suggestions on what heads to put on this thing? cam suggestions? piston and rebuild kit? any and all upgrades I just have to do for longevity and power/ torque.... just some really good combinations to put out a lot of good long dependable power for a long time.

Also, looking for places to take it to have it washed REAL well and have all my machine work done for a good price? I'm thinking they just need to be honed to new pistons if it hasn't been bored before, right or wrong here? Plus the heads are an adventure of their own if I use the ones i have. FUN FUN

I'll get some pictures up soon of it and how far I've gotten into it.
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amx39068 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote amx39068 Quote  Post ReplyReply Direct Link To This Post Posted: Apr/14/2012 at 9:29am

If you have to get new heads anyway, get either 291Cs (for .5 extra compression) or individual stud 090s or 993s (the last 3 digits on the casting number).  Most likely the heads you have are bridge rocker heads and for much over 6000 RMP you will need to convert them to indifidual rockers so why not start off with the rockers already provided from AMC.

Stock late 401 pistons have a "soup bowl" dish and are 8.5:1 compression due to the -41c dish whereas high compression 401s have -28cc front to back valve reliefs on either side of a center ridge.  The standard bore is 4.165 which you can easily check with a cheapie digital caliper from Harbor Freight http://www.harborfreight.com/6-inch-digital-caliper-47257.html or Sears Crafstman http://www.sears.com/shc/s/p_10153_12605_00920335000P?mv=rr&i_cntr=1334409909590
 
My favorite 401 build combination is with a set of Bulltear's, Wiseco's or Diamond's custom D shape -27cc dish high compression 401 pistons with the big chamber 090 or 993 heads, the Summit 8601 cam, a torker, bigger tube headers, a nice street/strip port job on the heads with roller rockers, Malllory self contained Unilite Dizzy or Pertronix III insert and a 750 - 800 CFM carb like what is in my SC/Rumbler. If you plan to do the block right and deck it to square it up, the Wiseco pistons are already .010 shorter than stock so you can deck the block the same amount to retain the near zero deck height.  The 401 in the SC/Rumbler goes like a batoutofhell and has more power than you can put down to the road yet is still resonably well mannered on the street.  It is a total blast to drive but will sit and idle at a light without sounding like it wants to die at any minute. 
 


Edited by amx39068 - Apr/14/2012 at 9:32am
Dan Curtis, AZ AMC Collector Quality Restorations & Parts - amcmusclecars.com
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taplercj7 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote taplercj7 Quote  Post ReplyReply Direct Link To This Post Posted: Apr/14/2012 at 9:20pm
Thanks a ton for the info! about how much horsepower/ torque will I get out of that "torker" setup you described? Also, Do i need new rods too, or are the stock ones fine for this much power? what rockers should i get if i make them independent?
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amx39068 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote amx39068 Quote  Post ReplyReply Direct Link To This Post Posted: Apr/15/2012 at 2:46am
Depends on the heads, pistons, cam and carb you elect to use, all of which can make a big difference in total output for both HP and torque.  With stock soup bowl dish pistons, 8601 cam and a 650 carb you are probably close 400 HP and somewhrer around 450 lb ft of torque and with a 750 - 800 carb you an add a little more but 8.5:1 compression will keep both from getting too high.  Bump up to 9.0 and both will be a little higher and bump up to 9.5 and it will higher still.  Add a good port job and a great flowing exhaust and it will help a lot.
 
Remember, an engine is nothing more than a big old air pump so the better it breathes in and out the more HP and torque you will get. Too much carb and not enough exhaust flow will hold it back and too little carb and too much exhaust flow is not good either.  The best approach is to match everything up and don't spend money on things that won't help you get what you want out of the engine. 
Dan Curtis, AZ AMC Collector Quality Restorations & Parts - amcmusclecars.com
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Post Options Post Options   Thanks (0) Thanks(0)   Quote captscot Quote  Post ReplyReply Direct Link To This Post Posted: Nov/06/2014 at 7:46pm
Hi, I know this thread is two years old, but if you'd know the following. I'm the original owner of a '72 Javelin that came with a 304. I've waited decades to upgrade it to a 401, so I'm beginning my first 401 rebuild which consists so far of a std bore block, pistons, rods, crank and NOS camshaft. You mentioned 993 and 090 heads, heads from 1971 and '73 respectively. Since my car is a '72 I'd like to keep everything stock and locate '72 heads which have the casting number 3213948. '72 heads should be as good as the other two mentioned, but never see any available. Is there a reason for this?

Second, for street used, would 291C heads cause a lot of pinging, unless every tank of gas has octane booster?

Lastly, for all engine bearings, Federal-Mogal is the best brand to go with? Thanks much, Scott
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Post Options Post Options   Thanks (0) Thanks(0)   Quote gremlinsteve Quote  Post ReplyReply Direct Link To This Post Posted: Nov/06/2014 at 10:10pm
Bearings seem to be all over the place these days.
A can of octane boost will do nothing for you.

Find a good set of heads, there all the same on the outside and inside. Except early heads have a screw in stud, late heads have bridged rocker systems.

Local guy to me and a forum member is a decent builder of amc motors. Hard to find a good machinist that knows the particular little things that they like and need.jcisworthy is his screen name.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote BassBoat Quote  Post ReplyReply Direct Link To This Post Posted: Nov/09/2014 at 8:29am
Just a suggestion, before you buy pistons, you need to measure the bores.  Check for a ridge and undercut at the top of the bore, even if the rest of the bore is a perfect as you think it is, the undercut is where the top ring will end up.  Check for taper and out of round.  Almost every block I have seen needed to be bored to be right.  Some exceptions, I have a Buick 455 that had 170K miles and was fine with standard bore, but honestly, you can't tell by looking.  
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