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Another 401 build and discussion thread....

17K views 183 replies 22 participants last post by  CSP 
#1 ·
Since I don't want to derail-highjack someone else's build thread I'm going to start my own.

1) My 401 spun a bearing and is done....

2) This will be my first individual build...

3) I'm new to AMC and their idiosyncrasies...IE oil pressure and drain back issues I've read about

4) Call me stubborn, but I'm not gonna take, what I feel could be, the easy route and drop a SBC into it.

The CJ (see profile for specs) is going to remain primarily an occasional daily driver that I want to be reliable and capable of moderate off road use.

The PO did the 304-401 swap and the 401 appears to be all OE. Based on the block (3198951) and head (3216090) appears to be of the '73-'74 vintage....which goes with the build tag on the valve covers (606Z21), which I'm told translates to June 21, 1973... Z denotes 401.

That being said, my research for similar builds had led me come up with this "preliminary" spec sheet:

Providing the bore just needs a hone, new .std pistons. I'm undecided on brand, thinking cast will do......I want to keep the comp around 9:1 (8.5:1 is stock I believe)

Re-use stock forged rods if possible.

I'm assuming the crank will need to be turned .010, will deck the block as needed, and hope to balance the rotating assembly.

Heads will be rebuilt...port matched

Edelbrock Performer Intake (EDL-3731)

Unsure on carb just yet...Holley TA 670...?

And for the most important, most debated piece...the cam. As of right now I'm leaning towards a Comp Cams XE256H kit from Summit, mainly because it comes with lifters, valve seals, timing and roller kit ect.....

MSD HEI with 6AL

....and of course all new bearings - seals - hoses and gaskets.

I'm sure I'm forgetting a few things, but that's basically it.

 
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#2 ·
UBERK,

I'm in! Sounds like a fun build! Here's a few "idiosyncrasies" I learned from my build.

1. Much to do is made of AMC's oiling problems. You will read plenty about certain "oiling mods" that are suppose to help. In truth, I think most of that is over-blown, or applies to racing applications. For a low to moderate RPM, high torque, CJ engine the stock oiling design is just fine, IMO. I wouldn't waste my time chasing most of those mods, again.

2. If the block is to be bored, be sure the machinist has the proper AMC torque plate.

3. Expect to be frustrated when sourcing certain parts. Especially OEM emissions stuff, if you have to worry about that.

4. Shawn's your man on the cam. I'm sure he'll be along soon. :thumbsup:

5. There's a ton of sage AMC engine builders, here. They walked my dumb arse thru the process, and we had a lot of fun along the way. Try to post lots of good pics if you can.

Looking forward to it. :cheers2:

Matt
 
#4 ·
Matt1981CJ7 said:
1. Much to do is made of AMC's oiling problems. You will read plenty about certain "oiling mods" that are suppose to help. In truth, I think most of that is over-blown, or applies to racing applications. For a low to moderate RPM, high torque, CJ engine the stock oiling design is just fine, IMO. I wouldn't waste my time chasing most of those mods, again.
I definitely don't want to over think any thing here, but at the same time not discount anything. This will definitely not be a "race" engine, however I am the type of person who does believe in preventative medicine, so if there's an opportunity to improve a design flaw I will consider it.
Matt1981CJ7 said:
2. If the block is to be bored, be sure the machinist has the proper AMC torque plate.
Yes, i will definitely make sure the machine shop has AMC experience
Matt1981CJ7 said:
3. Expect to be frustrated when sourcing certain parts. Especially OEM emissions stuff, if you have to worry about that.
I am emissions exempt so I am considering scrapping the smog pump, related parts, OE exhaust manifolds and running headers, true dual with side exits just in front of the rear tires.
Matt1981CJ7 said:
4. Shawn's your man on the cam. I'm sure he'll be along soon. :thumbsup:
I'm assuming the discussion on the cam will be lengthy.....
Matt1981CJ7 said:
5. There's a ton of sage AMC engine builders, here. They walked my dumb arse thru the process, and we had a lot of fun along the way. Try to post lots of good pics if you can. Looking forward to it. :cheers2:
Sounds good...I'm expecting this to be a 3-6 month process. I've already sourced my MSD HEI dizzy, coil, 6AL and Eddy Performer intake locally from another Jeeper who is parting out his 304, with only about 3K mi on a fresh rebuild, out in favor of a Chevy 5.3. I don't even have the motor pulled, but saw an opportunity to save a few $$$. We believe his issue was cam related and he got tired of fighting it..
 
#6 ·
At this point nothing is set in stone, I just love that look.

As noted above Ive already got a new intake, MSD HEI ignition system, planing on a new carb (again undecided which one just yet) and will probably switch to headers as well.

Is there any market for my old intake, carb (which I believe is a MC 4300...??) exhaust manifolds w/ emissions equip and dizzy?

If so Ill clean them up and post them in the For Sale.... Just wondering if its worth my time to clean them up, take the pics and make the post?
 
#7 ·
I doubt you'll get much action on the old cast-iron intake. That's a scrap-value item, IMO. I also have one occupying space on my shelves.

The exhaust manifolds, on the other hand, should bring a pretty penny. The AMC V8 manifolds actually flow quite well, and they seal up better than most headers. I paid $90 for the rusted set that I put on my 360. They cleaned up nicely, and still look just as good after 4K miles. I'm a real fan of the VHT manifold paint. :thumbsup:

Matt
 

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#8 ·
The exhaust manifolds, on the the other hand, should bring a pretty penny. The AMC V8 manifolds actually flow quite well, and they seal up better than most headers. I paid $90 for the rusted set that I put on my 360. They cleaned up nicely, and still look just as good after 4K miles. I'm a real fan of the VHT manifold paint. :thumbsup:
Matt
Those look good.. :thumbsup: Perhaps Ill sit just sit on them till I cross that bridge.
 
#9 ·
Another reason I chose to use the stock exhaust manifolds was for the "heat stove" feature on the factory air cleaner. It draws heated air from around the manifold to prevent carb freeze-ups, and shortens warm-up times.

In my neck of the woods, the closed factory air-cleaner is a superior system to any aftermarket open setup, IMO.

Matt
 
#13 ·
I mentioned how I'd approach it on the other thread. Been sick and don't feel like typing :drool:

OP,

The Comp 256 in a 401 should behave exactly the way Matt's Lunati 250 does in his 360 so maybe you can get him to post his videos. Might have to twist his arm though :p

The shelf version of Comp's XE256 is as small as I would go for your engine. You could even step up to the 262 without any fear of being over-cammed.

Those factory exhaust manifolds are some of the best I've seen and won't present any problems at this level of build.

If you don't care how much power it makes above, say, 5,000 rpm, you could have the 256 ground on a 106 LSA with the smaller exhaust lobe from their lobe cam master catalog. Done that way, you could expect an easy 415+ or so ft/lbs out of it.

Shawn
 
#14 ·
swatson454 said:
The shelf version of Comp's XE256 is as small as I would go for your engine. You could even step up to the 262 without any fear of being over-cammed.
Pretty much where I'm at. I'll probably opt for the XE262 kit from Summit with springs, lifters, seals and timing roller chain.

Went to clean up the OE exhaust manifolds today and....



...easy fix...hopefully, but I had run out of patience by then.

Also, can someone ID this sensor, I can't locate it on Rockauto....



 
#18 ·
Matt1981CJ7 said:
Everything sounds good to me, except the side pipes, but that's subjective. ;)
I agree with ditching the side pipes. I had my single exhaust run out the side behind the rear wheel and it would give me headaches after 2 hrs on the trail. Had it run out the back and it much better. You would also have to run a very short muffler and probably run it under the frame unless you have a huge body lift.
I run a 360 with
.030 over bore
Performer intake, Performer 600cfm off road carb, Performer headers
Pertronics HEI
Custom Comp Cam, can't remember the specs off hand
325hp and 400ft/lbs at the flywheel.

Good luck with the build.
Oh yeah, 10,000 miles on motor with stock oiling and zero problems
 
#19 ·
Good luck with the build.
Oh yeah, 10,000 miles on motor with stock oiling and zero problems
Thanks for the info. I think Ive spent way too much time analyzing all the info on oiling mods. I feel pretty confident that with my level of build I wont need to do anything but add an extra qt....which makes me wonder if I did that when I changed the oil 3 weeks ago if I would be in this position... :confused:
 
#22 ·
I think numbers 2 and 3 from Matt's list should be considered mandatory. Keep in mind, you want the pressure relief valve to regulate the pressure seen at the bearings, not what was required to get there.

Another thing to think about: if you're going to be doing these mods, it's best to have them done before the cam bearings are installed. Those little buggers will trap an enormous amount of junk that brushes can't get to.


Shawn
 
#23 ·
factory rods when done right will spin to 6,500 rpm all day long

I have never done the gasket match or the pump port enlarging I do run the oil line under the intake

the painting of the lifter gally keeps oil runin off but make sure it is super clean or it will come off

keep the crank to rod clearence close

when you get your heads done use good valve seals not the factory junk

check your cam gear oil passages out reay close for burs in the oil passages
 
#24 ·
I've been slowly chipping away at this, Holidays have had a lot to do with it.... Don't plan on getting the motor pulled for another week or two, but have been stock piling a few parts and cleaning some up to reuse:
Got references on 3 local shops to do the machine work, I'll be stopping by their respective shops at some point next month to chat with them and choose who m going with.
 
#26 ·
I'm glad to see another AMC 401 going in a CJ .....
I'm not a technical guy but I can offer the details of my build in hopes that's it helps or ads to the discussion .....

This is the set up I had built for my 401 with Dyno'd specs...... Most of the external engine components were transferred from my 304 ......The quick fuel technology carburetor was the stinger at the end of my build (an extra $600) as my Edelbrock thunder series would not meet specs on the dyno according to the engine builder.

Hope this helps.....

AMC 401 Performance Pump Gas built by CMEngines of SC, 10:1 Compression & Oiling Modifications
- 427 Max HP @ 5300 RPM's
- 498 Max Torque Ft. Lbs. @ 3900 RPM's
CN: 3198951


Quick Fuel Technology
Street Carburetor 680 CFM VS
Part#: SS-680-VS

Holley 2 110 GPH "BLUE" ELECTRIC FUEL PUMP WITH REGULATOR

Edlebrock Performer Intake (Powder Coated)

Aluminum Valve Covers (Powder Coated)

MSD Blaster 2 Coil Hi-Performance

MSD Pro-Billet Ready to Run Distributor

MSD Ignition Control 6A

Moroso Blue Max Race 8mm Wire Set

Professional Products 91102 AMC Harmonic Dampener

Bulltear AMC Serpentine Aluminum Pulley Conversion Kit

Headman Hedders

Milodon 16271 Performance Aluminum High Volume Water Pump for AMC
 
#30 ·
I would spend the money on Harland sharp rockers instead they are the right length for amc heads the others are not always right as they say they are push rods get a checking push rod and get the right length made to keep the rocker to stay in the center to a little off center through valve movement

 
#33 ·
UBERK,
Do you still have the factory choke heater tubes? If so I will buy them off you if you would like to sell them.
Sorry, just sold the OE intake today and sent them with it.

Ford shock towers are a cheap upgrade in strength with more travel.
I did the F250 towers on my K5, they work well and are inexpensive...$35 locally for the set from a dealer. Heres the link to the instsall on my K5: http://www.gmsquarebody.com/forum/showthread.php?t=4639

....takes a bit more work than whats needed on a CJ, but I loved the extra travel. I also added 64" rear leafs at the same time, that ride was really plush for a full size straight axle SUV

A local shop makes these:



...which Ill probably end up going with....at some point.
 
#34 ·
Since the CJ is down for a motor rebuild there are a few other small projects I'm going to do, like replacing some 38 year old mounts....

Got the body kit and trans mount in today:



Old v New...



I'll be grabbing all new G8 hardware this weekend to install it.

I had a brain fart when ordering the motor mounts though and got a set for a 258. After looking up the correct PN they are $110 on Summit....however I can get a set of very slightly used MORE Bomb Proof mounts for $125 from a local Jeeper.....

I'm thinking I'll do the poly though as this thing will be primarily a street rig and only see mild trails.
 
#35 ·
Found my problem....





















I'm wondering if there was a clearance issue with the pistons and heads....? I don't see any damage on the heads or indication the valves are ruined. Lifters, pushrods and rockers all look good.

Lost some bearings, found shavings in the bottom of the pan.
 
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