'71 Duster 440 or 360? Pros and cons

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bridger5228

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I have a '71 Duster. I just bought it a few weeks ago. The car currently has a 360 in it with a 904 tranny. The 360 is pretty tired and is probably ready for a rebuild. I picked up a 440 last nite on a whim for only $375. It is complete and said to be running. I would probably rebuild it anyways. The 440 is a 75-78 motor, so nothing special. It did come with a Performer intake. I have no idea what is done to it internally. I am sure it has been rebuilt at least once already as it has a tag from a local engine rebuilder. I am curious to hear what you guys think about my situation. Is the 440 swap going to be worth the time and $? I have never driven a big block Mopar before. I have certainly never stuffed one in an A body before. Is it going to be more worthwhile to stick with rebuilding the 360??? Opinions appreciated. Thanks.
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Yes....no....well maybe.....All depends on what you want to do with the car and what you are willing to put up with. A big block does not make for the best handling street car but if built properly the torque will make your eye balls recede in your skull a bit, but at the same time if the small block that is in it needs to be gone thru a stroked 360 is not going to be a slouch either. Good luck with your decision......and welcome to FABO.....
 
What can you guys tell me about this 440? I noticed the water pump outlet seems to be on the opposite side of most that I see pictured online. Is this likely out of a motorhome or something?
 
just remember you are going to need a 727 for a big block ...

I would stroke the 360.....big inch small block..still have a light engine package along with the current 904.
 
That engine does have the truck/motor home water pump housing. Not a big deal though. That's what I ran on my 440 Dart for a couple years. If you want to change it you could very reasonably. A new aluminum housing is only $100.
 
That is the later pump housing. They changed at some point in the early-mid 70s. No big deal. You can run it or get an earlier housing (there are a couple of different ones of those, too). Alternator brackets are particular to each one.

For me, I'd go with the 440, but you will need to open your wallet a bit. It's not that hard a swap, but make a plan before you jump in. Spend some time wandering around the tech pages at www.bigblockdart.com to help make the decision.
 
I just did a little bit of tear-down to see what I have. Everything inside the motor is very clean. My heads are 3462346 casting. Are these considered to be OK for performance use? I would definitely have to rebuild this thing to get any power out of it. The cylinder walls look awesome but, the flat-top pistons are .45" down in the hole!!! Is that fairly typical for these late 440's? I appreciate all the responses thus far!
 
i'd go with the 440. u can get engine-mounts,headers and etc u need to the engine in at engine-swaps.com
the heads are ok for performance use as well, i would upgrade to the 906 heads or the 915 heads. u can have those 346 heads rebuilt with bigger intake and exhaust valves to handle better performance.
 
The later 440 's fall out at about 8 to 8.5 to 1 compression. The 346 casting heads would have the induction hardened exhaust valve seats from the factory. Have seen a lot of the heads that were induction hardened crack between the intake and exhaust valves. With the compression this low you have to be extremely causous on the cam choice as something too large will gut the bottom end on power. Youll need a big block tranny, custom length drive shaft. The 440 can be put on a weight reduction plan aluminum heads, intake, wp housing etc that will get it down to about the same weight as the all cast iron 360, would have to dig out performance chassis book for exact numbers.
 
Actually the .45 is the measurement of the wear mark at the top of the bore from the rings. I haven't found a socket big enough to turn it over and check how far down in the hole they are exactly.
 
Contemplating the same thing here..............I think I am going to go with a 340 even though I have a fresn 440 in the garage. This is my first car build so I want it to be streetable and fun. I think a healthy 340 with a 4 speed will work - plus I will have my disc brakes!!!
 
Your gonna have to spend twice as much to build and put the 440 in.Also need a 727 trans as said.New headers,rad,motor mounts.I vote to rebuild or stroke the 360.All depends on your wallet size.
 
You are going to be running down the road sooner in the 360 with a lot less headaches. Stroke that dude, do some head work or get some aluminum ones, beef up the 904 to handle your intended power and get all the input you can from people on this forum!! If you don't stroke it you still can get some awesome power from it. Very important!!!..........If you pick and build the 360 with components that will work together, you will be very happy.
 
I'd say if you just got thte car, drive it and see what you like or don't. The 440 swap can cure some issues, but causes others. So see what you dont like first...
 
It all depends on what you want to do with the car? If it's a street car, I would stick with the small block. I've had a few big block street cars, and I didn't care for it. JMO
 
Big block's in a bodies don't sound that great, they are light cars, more bang for the buck if you plan anything accept drag races.

If you do the small block, then you can take advantage of everything these cars are capable of, they can handle very well.

So when your done waiting 2 hours for 11 seconds of straight ahead glory, you can take it to a road course and have some fun. :)
 
I did the swap once before. In my thoughts... unless you are drag racing... the cost of rebuilding the 360 into whatever you think you will get out of the 440 will match whatever you spend to build the 440, buying a tranny, brackets (omfg don't forget having to find brackets), mounts, tranny mount, modifying the driveshaft.... etc...

As others have said, you'll get what you want out of the 360, faster and cheaper. Unless you are drag racing. With that being said, a 440 isn't a boat anchor and you wont' really notice the difference in handling either (unless you are road course racing).

If I could have done my motor swap different, I probably would have rebuilt my small block with more power than the big block ended up having, and kept the big block as it was a date code correct for my big block car in the garage.
 
I think I'd measure the bore on the 440 and make sure it isn't maxed out on overbore and due for another, before I did any wondering at all...
 
It may be bored already but the cylinder walls still have visible cross-hatching so it would only need a hone job. From what people are saying in this thread it's almost as if nobody thinks a 440 is a worthwhile swap. I just found a BB 727 that I could buy for $100....
 
my first car was a 1968 GTS 340 727 8 3/4.
My second car was a 1970 dart swinger 440 727 8 3/4 with 3 inch inboard leaf springs and front discs

The gts had the factory rallye pack suspension

My third car was a 1971 demon factory 318 car with only a 340 installed, no discs no sway bar

from my experience a 440 in an abody can be had really well if you add better torsion bars disc brakes and dont move your leaf springs inboard for me that sucked on the street.

If my '70 swinger didnt have inboard springs it wouldve kept up with the old GTS around the turns.

The 318 demon, Mann that B_tch would float like a boat !!!

One other thing I learned was anything smallblock Im only game for a 904 no 727 behind any small block for me
 
also you can do a 3 inch engine set back with that 440, although its not that bad in factory placement.
 
bridger5228 said:
It may be bored already but the cylinder walls still have visible cross-hatching so it would only need a hone job. From what people are saying in this thread it's almost as if nobody thinks a 440 is a worthwhile swap. I just found a BB 727 that I could buy for $100....
Click to expand...

Not sure what you already have for it but to get a big block in and driving (not including the brakes or suspension that IMO are nice but not necessary) you'll need the complete engine (including distributor), trans, convertor, 727 slip yoke, mounts, headers/manifolds, kickdown (if used), driveshaft, radiator (unless you have a larger one with the engine-matching inlet). I'd also consider weld in frame connectors aws mandatory. And- in the case of engine and transmission at least, they will need to have some parts or work tossed at them.
The reasons can only be yours. It's cool to say you have a 440 Dart. It's a cruise night impressing package. But when the pedal gets pushed, a 360 will run very similar or better, and will be a better "all around" performer as a driver. At least that's my opinion.
 
it's going to cost a ton of money to rebuild the 440 adn 727 and get it installed. first let me say this, there is no better hotrod than a bigblockdart, period. this being your first time attempting to install a rb into an a-body it's going to be a patience trying ordeal. please take note of the amount of hair you have before you try it because you will have less afterwards.
this is what i'd recomend, set the 440 and 727 over in the corner and rebuild the 360 and start driving it. we're talking fun here. after that is taking place rebuild the 440 and 727 to pretty good horse power that you want. start collecting all the other parts you're going to need to get it installed. find a rolling a-body drag car and put it into it and then start having some eyeball popping fun at the drag strip.
 
bridger5228 said:
It may be bored already but the cylinder walls still have visible cross-hatching so it would only need a hone job. From what people are saying in this thread it's almost as if nobody thinks a 440 is a worthwhile swap. I just found a BB 727 that I could buy for $100....
Click to expand...

I like Bob Shingler's advice. Buy the 727, collect the parts, buy a drag car for that stuff, but drive the heck out of the 360 car in the meanwhile.

I had one that I had a big block in it and put 11,000 miles on it in the 11 years that I owned it (which is very sad, it was broken most of the time). And I've got another that I have 20,000 miles on it in the last 5 years (weekend driving, this car is amazingly reliable, almost no options, small block). They handle very close (both had/have upgraded suspension), the big block was only a little faster off the line, good for burning tires, but I put posi and bigger tires on the small block car, thus they are about the same. The small block can get 18mpg, the other had a best of 13mpg. For daily driving on the street, there's no real difference to me except mpg. I never went drag racing, and never did track racing. I only recently got a 360 small block myself. I'm very excited about having a motor that handles like a small block, but with a bunch more torque. When I blow my 360, I'm going to port the heck out of the heads, aluminum intake, good pistons, valves, medium aggresive cam, building it for as much torque as possible. (spin the tires, but cruise at all other speeds :p)
 
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