from '72 on, AMC used the Mopar auto they put behind Hemi-cars with auto trans, but I guess some Jeeps used turbo-400s. You WILL have a pile of 401 parts, or maybe just a spun-bearing, if you don't use a dry-sump. In the Trans-Am era, Penske-Donohue had 23 consecutive bearing failures UNTIL they went dry-sump. Your mods sound good, you'll have FUN for a while. I took care of my 390cu" AMC in a '68 AMC AMX. At idling, it spun a main, in the Am, after some non-over-revved street-drag "action" the night before, and I hadn't had the "Hot Rod" magazine oil-hose-fix, and I hadn't gone dry-sump like Penske had had to do to win those two years he did {--he not only went dry-sump, he also used only after-market Traco "304" blocks, like he had earlier won-with in his Sunoco '69 Camaro as a "302" }. You CANNOT, for long, race an AMC V-8, without a dry-sump system, or the Hot-Rod oil-line fix to the mains. Hot Rod ran a stock 401 AMC V-8 in a '74 Hornet "X" Hatchback with the stock 360cu 2-barrel, lame a-s" V-8 removed in favor of a new [crate] 401 in its entry into The Cannonball-Baker Coast-coast "race", and the stock-401, certainly less than 400hp, but probably more than 330hp, spun a bearing, causing "Hot Rod" Extreme Embarrassment for a DNF, where they thought they were a "Shoo-in" to WIN. I believe the swap was done by Randall AMC in Mesa, Az, which had done DOZENS of 401 swaps from all types of AMC V-8 cars, plus they campaigned a trans-am Javelin for a while. Being a small company, AMC didn't do a "fix"--merely cast thousands of extra 360 blocks for the FLOOD of warranty claims that came in. Wifey & I bought a '70 AMX that had had its 390 replaced under warranty. The guy that had a 401 in his SUV-sized jeep, probably didn't street-race it, did he? I will NEVER own an AMC V-8 that hasn't been dry-sumped. It's WHY they never really "caught-on" as a Performance builder, even though "On Paper", they LOOK like the "Hot set-up." Do what you wish, but you have been advised.
your "handle". Oldsmob455 IS the "answer". Find an Olds/Buick 455 cu" V-8{--get the Racer/over-the-counter-ONLY 'Stage-2' for rarer-than-AMC bragging rights,} and "Not-Worry" about dry-sumps;). It'll mate-up to your 400 Turbo-hydro, assuming bell-housing compatibility. Jeep used to use the Buick V-6, before AMC bought them. Buick USED to have a non-light casted "401". Do you think AMC might've bought the tooling for the block from Buick, putting their own chevy-like-flowing heads on, and dumping the smaller-valved "Nail-head" older Buick heads? Buick dumped their old architecture 401 to a 400 for '66-69, moving to 455 in '70 on. I wonder...
When Kaiser had Jeep, they also used the Buick 350 in Gladiaters and Wagoneers up until 1970. My 1970 was powered by the Buick 350 with a Turbo 400. Used to punch it in low range drive, and it was finished shifting by the time I hit 15mph. Just so funny.@@jackdale9831
I had a AMX with a 343 in it around mid 1980's. That motor had over 150k on it and the pistons were never out of it. I beat that car pretty much and it never blew up. When it was cold outside the thing really woke up and almost felt like a 390cid!
Had one of these with the 343 and auto transmission early 1970’s. Yep, blew that tranny… had it rebuilt. It was fairly quick, generally beating plain vanilla 4bbl 350 Chev’s. AMC rated them at 280hp and the SST weighed not much more than 3,100lbs. I am disappointed to hear about the cast rods and crank. Truly a recipe for disaster when seeking more power. Mine was stock though and never had a problem with the motor. Just that darn transmission, which the rebuild guy did say when he was done with it “don’t beat on it, it won’t last”. I of course couldn’t keep my foot out of it at age 17 at the time. It was starting to out again after just a few months.
Nice video and some great comments here, thanks again for your posting. I have told my story on a couple of other threads elsewhere, but I would like to briefly share here. 1968 I bought a new AMX, 343, Bog Warner auto, with go pack, along with the dealer install rally pac instruments and dealer install AMC all chrome magnum rally wheels. Over the next 3 years these changes were made to the little 343. Replaced original 3.15 rear gears with dealer install 3.73, replaced the oil pump, along with and added separate oil line to feed the back main bearings which can starve for oil. Replaced the 343 stock cam with the AMC 401 white stripe cam, which was used in the 1970 Rebel Machine 390. Replaced the intake with an Edelbrock R4B and larger Carter, 9625 with electric choke. A set of Cyclone exhaust headers matched to the stock heads, flowing through full exhaust with Hush Thrush mufflers. The stock Bog Warner model 11 was rebuilt with the model 12 insides, updated the clutch pac with better, metal impregnated semi fiber disc, higher pressure oil pump in trans was added. The model 12 came with the 390 engine which the 343 should have had instead of the model 11. The 343 that I had, was a very strong running engine, and wanted to greatly pull past 5,500 rpm's where I shifted at. A true race story: I raced the same AMX, 1970, 390 go pac with 4 speed twice, with the same results. Just off the start, I could pull a good fender on him, at 80 or 85 we were dead at the side even both times. I just loved that little 343 engine, and have thought, if AMC built their version of a Z 28, this would be it. I would just give them 340 Dusters fits all day long. If I could do it all again, the little 343 would be my choice. Speaking of the 401, and it is a great engine indeed. But I believe in 1974 there was a change to the rocker arms on their 401 V 8's. AMC for some reason went to a bridge connection, linking the rocker arms together. I have read that this made some modifications difficult to make, and to go with the pre 1974 head design instead. I just love all them AMC cars.
Nice find! Good luck. My current project is a 78 cj7 304 turbo 400. The 304 ran 1 year without checking oil! It knocks real bad now. Found a used 304 for 200. Thanks for sharing.
Kenneth Cohagen do you still have that 343 sitting around? I could use a donor for a car I want to build with my son, who has Autism. But I can't afford to do it without help. If not , no biggie. We'll get there some day!
Kenneth Cohagen oh, yes, I almost forgot, there is a guy making main study girdles for 343/360. It would even work with the 290/304 engine. The 401 and 390 has thicker main webbing, so there's enough meat for a 4 bolt conversion and no need for a main stud girdle. The dog leg heads flow 50% better on the exhaust side. At the time there was nothing but the Boss 302/351 Cleveland that could outflow it Small Block wise. The AMC block is really a small block, but shares bore spacing with Big Block short and tall deck big blocks. But the weigh in lighter than a small block Chevy. The heads outflowed even the first few years of aftermarket aluminum SBC heads, which makes them a viable alternative even today. A little massaging will go a long way towards improving flow, and if that's not enough there are three Edelbrock aluminum heads, two stock replacement/ hot rodded types. And one that needs machining soma guy can port them the way he wants to. Then there are the Indy Cylinder head offerings, one near stock and the other with BB Mopar exhaust ports. The latter outflow the Big Block Mopar offerings within the same parameters. AMC came to the party late, but they did their homework!
Kenneth Cohagen the 390 and 401 have forged rods and crank. Way back when, they made a forged crank for the 290/343. It was a factory aftermarket part aimed at Trans racing. The 290 and 343 used what was called Armasteel, which were cast steel similar to Pontiac cranks of the era. AMC used GM's foundry under contract. The arms steel cranks are good to 6000 rpm or about 600 hp. After that it's best to seek out forged steel cranks. I wouldn't mind an Arma steel cracked 343 for my own project, with later dogleg heads. The major difference is the short turn radius of the port. The early square port heads are concaved. That really hurts flow! Later dogleg heads are convex and help support port velocity. They flow 50% better than early heads. All together AMC heads outflow everything except Mopar Hemis, Bigblock Chevy square port heads and Boss 302/251C heads of the era. They were the best flowing Small Block heads of the era, blowing away Small Block Chevy by a large amount. In fact it takes a new aftermarket SBC head to outflow the AMC. They also kept pace with Big Block Mopar, and in their aftermarket form from Indy Cylinder Head they outflow the Mopar heads. They were designed with port bias that aids in swirl of the entering air fuel mixture, and a long time head porter from Valley head service who helped design the heads for AMC told me that he could get more flow out of them than square port BBC heads! That's a lot of airflow!
The 390 and 401 block casting along with the special service block all had heavy main bearing webs that allowed them to be drilled and tapped for the four bolt main caps.
Awesome work! Could not find a 401, but recently put a 360 from a '78 Jeep J10 in my '68 Javelin SST. It has the dog leg heads and same exhaust manifolds which fit in the car just fine with no clearance problems. Hope this helps!
Couldn't see all that well but the absence of a displacement cast into the side could mean you have a service replacement block, they could be built into any 343-401
I knew of a guy locally that was able to get a lot of speed out of his 343 Javelin . 60 mph in 1st was pretty impressive back then but I saw him do it .
What have you done with your 343? I'm trying to get something together to build with my youngest sone who is autistic. I'm looking for any help I can get.
You bet! If you have any questions about this swap, let me know as I've basically done it a short while ago. Instead of the T400 that came with my engine, I had the BW flex plate modified to work with the bigger engine so I could reuse the BW. Too many mods (for my skill and budget) to use the T400. The BW works fine with my warmed over 360, but I don't know how it would stand up to the 401. Good to see another Javelin staying on the road - I feel they're far too often overlooked!
the better flowing cast iron exhaust manifolds came on cars with factory dual exhaust , but i have seen single exhaust motors with ONE the better flowing cast iron exhaust manifolds to grab heat for the intake breather and one crappy exhaust manifolds on the other side on 73 360 javlin i had :) AMC use up all parts they could not sell,,,,, All So come on man there no option better than the 401:) the 343 a supe up 290 its all cast and the 401 steel crank steel rod`s , from what i remember the bore limits were not high on any given block 20 thousands was maxing it , i had a 10 over 401 with one bad oversize bore cylinder,, i was told the option to bore it 30 was not a good idea the cylinder wall would be to thin and there be heat problems, so we had the piston nearld to make it fat`er , it didn't take long to ware down and start slapaing :(
from '72 on, AMC used the Mopar auto they put behind Hemi-cars with auto trans, but I guess some Jeeps used turbo-400s. You WILL have a pile of 401 parts, or maybe just a spun-bearing, if you don't use a dry-sump. In the Trans-Am era, Penske-Donohue had 23 consecutive bearing failures UNTIL they went dry-sump. Your mods sound good, you'll have FUN for a while. I took care of my 390cu" AMC in a '68 AMC AMX. At idling, it spun a main, in the Am, after some non-over-revved street-drag "action" the night before, and I hadn't had the "Hot Rod" magazine oil-hose-fix, and I hadn't gone dry-sump like Penske had had to do to win those two years he did {--he not only went dry-sump, he also used only after-market Traco "304" blocks, like he had earlier won-with in his Sunoco '69 Camaro as a "302" }. You CANNOT, for long, race an AMC V-8, without a dry-sump system, or the Hot-Rod oil-line fix to the mains. Hot Rod ran a stock 401 AMC V-8 in a '74 Hornet "X" Hatchback with the stock 360cu 2-barrel, lame a-s" V-8 removed in favor of a new [crate] 401 in its entry into The Cannonball-Baker Coast-coast "race", and the stock-401, certainly less than 400hp, but probably more than 330hp, spun a bearing, causing "Hot Rod" Extreme Embarrassment for a DNF, where they thought they were a "Shoo-in" to WIN. I believe the swap was done by Randall AMC in Mesa, Az, which had done DOZENS of 401 swaps from all types of AMC V-8 cars, plus they campaigned a trans-am Javelin for a while. Being a small company, AMC didn't do a "fix"--merely cast thousands of extra 360 blocks for the FLOOD of warranty claims that came in. Wifey & I bought a '70 AMX that had had its 390 replaced under warranty. The guy that had a 401 in his SUV-sized jeep, probably didn't street-race it, did he? I will NEVER own an AMC V-8 that hasn't been dry-sumped. It's WHY they never really "caught-on" as a Performance builder, even though "On Paper", they LOOK like the "Hot set-up." Do what you wish, but you have been advised.
your "handle". Oldsmob455 IS the "answer". Find an Olds/Buick 455 cu" V-8{--get the Racer/over-the-counter-ONLY 'Stage-2' for rarer-than-AMC bragging rights,} and "Not-Worry" about dry-sumps;). It'll mate-up to your 400 Turbo-hydro, assuming bell-housing compatibility. Jeep used to use the Buick V-6, before AMC bought them. Buick USED to have a non-light casted "401". Do you think AMC might've bought the tooling for the block from Buick, putting their own chevy-like-flowing heads on, and dumping the smaller-valved "Nail-head" older Buick heads? Buick dumped their old architecture 401 to a 400 for '66-69, moving to 455 in '70 on. I wonder...
When Kaiser had Jeep, they also used the Buick 350 in Gladiaters and Wagoneers up until 1970. My 1970 was powered by the Buick 350 with a Turbo 400. Used to punch it in low range drive, and it was finished shifting by the time I hit 15mph. Just so funny.@@jackdale9831
I had a AMX with a 343 in it around mid 1980's. That motor had over 150k on it and the pistons were never out of it. I beat that car pretty much and it never blew up. When it was cold outside the thing really woke up and almost felt like a 390cid!
Gotta love em
Had one of these with the 343 and auto transmission early 1970’s. Yep, blew that tranny… had it rebuilt. It was fairly quick, generally beating plain vanilla 4bbl 350 Chev’s. AMC rated them at 280hp and the SST weighed not much more than 3,100lbs. I am disappointed to hear about the cast rods and crank. Truly a recipe for disaster when seeking more power. Mine was stock though and never had a problem with the motor. Just that darn transmission, which the rebuild guy did say when he was done with it “don’t beat on it, it won’t last”. I of course couldn’t keep my foot out of it at age 17 at the time. It was starting to out again after just a few months.
Nice video and some great comments here, thanks again for your posting. I have told my story on a couple of other threads elsewhere, but I would like to briefly share here. 1968 I bought a new AMX, 343, Bog Warner auto, with go pack, along with the dealer install rally pac instruments and dealer install AMC all chrome magnum rally wheels. Over the next 3 years these changes were made to the little 343. Replaced original 3.15 rear gears with dealer install 3.73, replaced the oil pump, along with and added separate oil line to feed the back main bearings which can starve for oil. Replaced the 343 stock cam with the AMC 401 white stripe cam, which was used in the 1970 Rebel Machine 390. Replaced the intake with an Edelbrock R4B and larger Carter, 9625 with electric choke. A set of Cyclone exhaust headers matched to the stock heads, flowing through full exhaust with Hush Thrush mufflers. The stock Bog Warner model 11 was rebuilt with the model 12 insides, updated the clutch pac with better, metal impregnated semi fiber disc, higher pressure oil pump in trans was added. The model 12 came with the 390 engine which the 343 should have had instead of the model 11. The 343 that I had, was a very strong running engine, and wanted to greatly pull past 5,500 rpm's where I shifted at. A true race story: I raced the same AMX, 1970, 390 go pac with 4 speed twice, with the same results. Just off the start, I could pull a good fender on him, at 80 or 85 we were dead at the side even both times. I just loved that little 343 engine, and have thought, if AMC built their version of a Z 28, this would be it. I would just give them 340 Dusters fits all day long. If I could do it all again, the little 343 would be my choice. Speaking of the 401, and it is a great engine indeed. But I believe in 1974 there was a change to the rocker arms on their 401 V 8's. AMC for some reason went to a bridge connection, linking the rocker arms together. I have read that this made some modifications difficult to make, and to go with the pre 1974 head design instead. I just love all them AMC cars.
Thanks for the history. If you hit the playlist and watch the engine assembly we went with fully adjustable rocker arms. Thanks for watching!
Nice find! Good luck. My current project is a 78 cj7 304 turbo 400. The 304 ran 1 year without checking oil! It knocks real bad now. Found a used 304 for 200. Thanks for sharing.
alll amc v8s of the 2nd,3rd generations can have mains oiling issues which are easily solved with engine OIL LINE MODIFICATION KIT
..imo
Port matching the oil passages helps a lot also.
There was a factory replacement 360/390 block that had no engine markings on it. I had one in my old AMX.
+Kenneth Cohagen ya can boar that block out to fresh 390 :)
Kenneth Cohagen do you still have that 343 sitting around? I could use a donor for a car I want to build with my son, who has Autism. But I can't afford to do it without help. If not , no biggie. We'll get there some day!
Kenneth Cohagen oh, yes, I almost forgot, there is a guy making main study girdles for 343/360. It would even work with the 290/304 engine. The 401 and 390 has thicker main webbing, so there's enough meat for a 4 bolt conversion and no need for a main stud girdle. The dog leg heads flow 50% better on the exhaust side. At the time there was nothing but the Boss 302/351 Cleveland that could outflow it Small Block wise. The AMC block is really a small block, but shares bore spacing with Big Block short and tall deck big blocks. But the weigh in lighter than a small block Chevy. The heads outflowed even the first few years of aftermarket aluminum SBC heads, which makes them a viable alternative even today. A little massaging will go a long way towards improving flow, and if that's not enough there are three Edelbrock aluminum heads, two stock replacement/ hot rodded types. And one that needs machining soma guy can port them the way he wants to. Then there are the Indy Cylinder head offerings, one near stock and the other with BB Mopar exhaust ports. The latter outflow the Big Block Mopar offerings within the same parameters. AMC came to the party late, but they did their homework!
AMC service blocks dont have the pad where the displacement number would be. That 343 block had the numbers ground off purposely
Kenneth Cohagen the 390 and 401 have forged rods and crank. Way back when, they made a forged crank for the 290/343. It was a factory aftermarket part aimed at Trans racing. The 290 and 343 used what was called Armasteel, which were cast steel similar to Pontiac cranks of the era. AMC used GM's foundry under contract. The arms steel cranks are good to 6000 rpm or about 600 hp. After that it's best to seek out forged steel cranks. I wouldn't mind an Arma steel cracked 343 for my own project, with later dogleg heads. The major difference is the short turn radius of the port. The early square port heads are concaved. That really hurts flow! Later dogleg heads are convex and help support port velocity. They flow 50% better than early heads. All together AMC heads outflow everything except Mopar Hemis, Bigblock Chevy square port heads and Boss 302/251C heads of the era. They were the best flowing Small Block heads of the era, blowing away Small Block Chevy by a large amount. In fact it takes a new aftermarket SBC head to outflow the AMC. They also kept pace with Big Block Mopar, and in their aftermarket form from Indy Cylinder Head they outflow the Mopar heads. They were designed with port bias that aids in swirl of the entering air fuel mixture, and a long time head porter from Valley head service who helped design the heads for AMC told me that he could get more flow out of them than square port BBC heads! That's a lot of airflow!
Great progress and what a cool surprise to find a 401 with good compression to swap in. Thanks for the close up of the ring lands.
you can also find AMC 401`s in a international Scout. Search for an International 400 v8 and it is in fact a AMC 401`s :)
Not sure about the Scout, but their pickups for sure.
Wow, I never knew those 343 main saddles were so thinly cast.
They aren't thin; thats the norm for amc V8s.....I've never had a main problem with any of the amc engines i have built. Good to 500 hp.
The 390 and 401 block casting along with the special service block all had heavy main bearing webs that allowed them to be drilled and tapped for the four bolt main caps.
I mildly built a 343 in 1972 and I never had any problems with it. It was in a 1967 Rambler American.
Awesome work! Could not find a 401, but recently put a 360 from a '78 Jeep J10 in my '68 Javelin SST. It has the dog leg heads and same exhaust manifolds which fit in the car just fine with no clearance problems. Hope this helps!
Great video. I watched it in its entirity, I liked it, and enjoyed the ad as well! keep em' comming!
Couldn't see all that well but the absence of a displacement cast into the side could mean you have a service replacement block, they could be built into any 343-401
Un motor tan bueno como los de otras marcas de USA small block . Excelente ti video . GRACIAS POR COMPARTIR ¡
I knew of a guy locally that was able to get a lot of speed out of his 343 Javelin . 60 mph in 1st was pretty impressive back then but I saw him do it .
What have you done with your 343? I'm trying to get something together to build with my youngest sone who is autistic. I'm looking for any help I can get.
343 and 360 have same bore but the deck height difference :)
All 401's had forged cranks and rods.
The 390 had a forged crank and rods.
A lot of work behind the scenes to get to where you are today.
You bet! If you have any questions about this swap, let me know as I've basically done it a short while ago. Instead of the T400 that came with my engine, I had the BW flex plate modified to work with the bigger engine so I could reuse the BW. Too many mods (for my skill and budget) to use the T400. The BW works fine with my warmed over 360, but I don't know how it would stand up to the 401. Good to see another Javelin staying on the road - I feel they're far too often overlooked!
the better flowing cast iron exhaust manifolds came on cars with factory dual exhaust , but i have seen single exhaust motors with ONE the better flowing cast iron exhaust manifolds to grab heat for the intake breather and one crappy exhaust manifolds on the other side on 73 360 javlin i had :) AMC use up all parts they could not sell,,,,, All So come on man there no option better than the 401:) the 343 a supe up 290 its all cast and the 401 steel crank steel rod`s , from what i remember the bore limits were not high on any given block 20 thousands was maxing it , i had a 10 over 401 with one bad oversize bore cylinder,, i was told the option to bore it 30 was not a good idea the cylinder wall would be to thin and there be heat problems, so we had the piston nearld to make it fat`er , it didn't take long to ware down and start slapaing :(
You have a nice setup there, I'm a bit jealous I have to admit.
10 spline quadratrac T400 transmission.
Cool good luck
401 nice! I hope the next video is called "Two tire Javelin burnout video"
What does the oil gallery mod look like? If you have done this. Good videos
shop around ,matador 401 727 or turbo 400 jeep,
401 are brutes,steel crank,steel rods,can handle 500 hp.
Good idea with turbo 400. The Ford FMX as it was called fragile..lol. Great car..even with trunions ..
Badger pistons!!!