Ultra-Cheap 401 Build

[Colorado Yeti]

I purchased an AMC 401 out of a 1973 International Travelall a couple of months ago for $600. I have been looking for a 401 for about 10 years now and finally found one that I could afford. It is going to be installed in my 1976 CJ7 Levis edition Renegade .

My goal is to build the engine as cheap as possible but still make it reliable and stout. Right now, the engine is locked up tighter than a $2 Mexican watch, and it looks like it may have taken on water down the intake when it was stored in a lean-to. The previous owner (a friend of mine) assured me that it ran when it was pulled out of the vehicle approximately 10-15 years ago.

I am going to start pulling it apart and figuring out how to get it back to a decent running condition. My goal is to keep total expenses around $1200, including the price of the engine. I will probably hone the block, reinstall the original pistons with new rings, and install a new camshaft, timing chain and obviously seals. I may replace all of the bearings, depending if the tolerances are within specs and the original bearings look reasonable. I'll probably leave the heads alone, as they are pricey to rebuild.

I do not want to do a full rebuild of the engine, because I am going to restore the whole Jeep in about 6-7 years anyway. I could sell the original good-running AMC 304 to recoup some costs but want to keep all original parts off this Jeep as it is quite rare and original. I can sell some of the smog pump equipment off the 401 on E-bay, as that stuff has gotten quite rare and virtually impossible to find anymore. (I still have all the original smog equipment on my CJ.)

I will post updates from time to time on my progress with this project. I know that there will probably be skeptics, but I think I can build a nice 401 for around $1200.

 

[bzahler]

I am interested in this as I just bought a used 360 for my 7. I seen it run before I got it. I plan to just put in a new timing set,new seals and gaskets. I am hoping to be in it for under $500.

 

[Colorado Yeti]

Good for you! You may want to consider replacing the camshaft / lifters while it is out as AMC V-8's are notoriously hard on valvetrains.

Sometimes I don't think you need to spend $3000 - $5000 on a engine rebuild to have a stout motor. I have built plenty of cheap ones and have never had one give out on me.

 

[Colorado Yeti]

This is what the engine looked like when I pulled it out of the lean-to shed. Still attached to the crappy 2wd auto tranny from the International Traveall. (God, I hate automatic transmissions). Pretty grungy.

First thing I did was to remove the tranny then pressure wash it to get most of the grime off of it. Removal of the tranny was actually kind of difficult since the engine is locked up and it was difficult to access all of the bolts to the torque converter since I couldn't turn the engine. Eventually I was able to get at all of them.

I then carefully unloaded the engine out of my trailer by myself without a hoist and placed it on the engine stand.......that was interesting and a little bit scary. I drained the oil and was somewhat relieved so see that it had about 2" of water in the bottom of the pan, so I think that is why the engine is locked up, not anything to do with mischief in the bottom end (I hope).

I then removed the 2-barrel(!) intake and was again relieved to see that the valley was super clean, so I think someone has taken good care of the engine and has done oil changes religiously. There is definitely evidence of water ingestion in the front two intake runners.

I then used a wire brush on my cordless drill to remove the rest of the grime and pressure washed the engine again. It actually came out really clean. I looked at the head gaskets and they still have the original international red paint on them, so I think that this engine is virgin and has never had the heads off of it and therefore has never been bored. I have been told that this is really important with the 401's as they are prone to overheating of they are bored > 0.040".

Enough for today. Tomorrow I am going to pull the thing apart with my 13 year-old son and try to figure out why the engine is locked up. I'll also see if the crank and bearings are original grind....I hope so. I'll post more pictures tomorrow when I start pulling it apart.

 

[Colorado Yeti]

Here is my '76 Jeep with the tired AMC 304 that this 401 will be going into eventually. I will have to be patient and build it as I get time & money.

 

[Colorado Yeti]

I pulled the top end apart yesterday and found what I suspected. At some point in storage the engine got a fair amount of water and gunk in the intake. In the front two cylinders on each side, it looks like mud! The good news is that the block is standard bore and the rear 4 cylinders look pristine with no ridge to the top. Also, the bottom end is intact and everything appears to be tight. My plan is to probably sleeve the front 4 cylinders and replace the pistons with some higher compression hypereutectic pistons. I really want to keep the block standard bore if possible as I will have this Jeep probably for the rest of my life.

I plan to take apart the bottom end next weekend and try to get the pistons out of the block. That should be a challenge.

 

[007]

Here is my '76 Jeep with the tired AMC 304 that this 401 will be going into eventually. I will have to be patient and build it as I get time & money.

Ahhhh. Nice ride! My long lost older sister perhaps...

My 77




Sent from my iPhone using Tapatalk

 

[RiverandSand]

Sleeving is way more expensive than boring (at least in these parts), if the pitting isn't to bad .030 over might be a good option. You will need pistions anyway, Summit racing has several choices. By the looks of things you will need lifters and possibly a cam. Good luck, most good deals are rarely that.

 

[mtnwhlr]

If they aren't pitted you could ball hone it and just replace the pistons.

 

[Colorado Yeti]

Ahhhh. Nice ride! My long lost older sister perhaps...

My 77




Sent from my iPhone using Tapatalk

Wow....uncanny resemblance! Love your Renegade ! About that whole "ultra-cheap" rebuild thing....probably not going to happen. Riversand is absolutely correct that boring would be the cheaper option. But I would like to keep the engine standard bore if possible to avoid overheating issues. And I am definitely going to replace the cam & lifters with a more aggressive grind, although the originals that I pulled out of the engine look like they are in great shape.

I got a quote today from a local reputable machine shop to boil the block, re-sleeve 2 cylinders, hone the other 6 and install the rear main oil bypass line in the lifter valley for about $350. That sounds like a pretty good price to me and a good starting point, although I might have to re-sleeve 3-4 cylinders depending upon the degree of corrosion. I plan to come up with a final parts and labor budget in the next couple of weeks for the rebuild. I hope it is less than $2000.

 

[007]

Well I'm glad you've erased the dollar figure from you mind, because with what you are doing, it's just not sensible to cut too many corners. Whatever you do, just make sure you don't have to end up doing it twice. Old saying "the poor man pays twice."

The problem with a project like this is that is one of those deals where there's SO much you can find to do "while you're at it" that actually should be done. You have an engine there apart, so now's the time for new fuel pump, water pump, perhaps an upgraded intake manifold, cam, rockers, lifters, ground valves, new carb or EFI, new ignition, blah blah blah. It just never ends and if you skip something you'll kick yourself somewhere down the road.

It's a great spot to be in, but it's no fun if you're not willing to take the time and spend the money. If the engine you have runs fine - then TAKE the time and the money will come when it comes.

 

[Colorado Yeti]

The good news is that I am not in a big hurry. My AMC 304 in my Jeep is a bit tired but still runs strong and is very reliable. So I have plenty of time to build the 401 as I get time & money. I plan to build the guts well at the beginning and then probably add EFI when I restore the entire Jeep in 7-8 years.

By the way, where is the pic of your Jeep taken? Looks like Pearl Pass between Crested Butte and Aspen (which is where I learned to drive many years ago in our CJ).

 

[007]

By the way, where is the pic of your Jeep taken? Looks like Pearl Pass between Crested Butte and Aspen (which is where I learned to drive many years ago in our CJ).

I had to look though pictures to see the sequence, but based on the date and cleanliness of the Jeep that's the summit on Black Bear Pass, looking west.

 

[Colorado Yeti]

Aha! Still haven't done that one yet but on my bucket list.

 

[Colorado Yeti]

I pulled apart the bottom end today. The good news is that the engine is completely original. The Clevite rod and main bearings still have the American Motors symbol and the old school "AM" markings on them. The bearing demonstrate minimal wear with the exception of the middle thrust main bearing (moderate wear). The crankshaft journals look pristine.

5 cylinders look excellent with no ridge wear pattern noted on the upper edge. The pistons popped right out on those cylinders. The remaining 3 of the cylinders are pretty bad due to extensive corrosion from sitting with water in them. I literally had to break the pistons apart in those cylinders to remove them from the block.

I am ready to take everything to the machine shop now. I am reconsidering the re-sleeving thing and am considering boring the block instead. Lot's to think about.

 

[Colorado Yeti]

More pics of the cylinders

 

[Colorado Yeti]

Here are some more pics of my Jeep. Probably take the block in to the machine shop in the next couple of months to get prepped.

 

[Colorado Yeti]

Here's an update. I just picked up the engine from the machine shop. The had to re-sleeve 4 of the cylinders due to extensive corrosion then they bored it .030 over. The added the oil upgrade and installed the cam bearings / freeze plugs. The crankshaft was in excellent condition and they just had to polish it. She shot-peened the rods and tore the heads down, but didn't build them out yet, as I have to save up the money for that.

Here's some pictures. Now to save up the money for the pistons, camshaft & heads, then I'll put it back together.