66 Dart 360 Swap Questions

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tandart66

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Hey all, I am currently in the process of ordering parts to build and swap a 1976 360/904 into my 1966 Dart 270 (formerly a slant/904 car). I have a couple of questions that to my understanding haven't been talked about clearly on the other threads: What radiator would fit in the car with the 360? What manifolds/headers (cheaper the better) would fit with the least amount of hassle? What other parts besides motor mounts would I need to make the swap successful? How difficult would it be to run dual exhaust? Any help would be greatly appreciated, and help move the project along tremendously!

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All the above has been talked about in great lengths if you use the search feature.

SN: welcome aboard.
 
You need to sit down and start reading, the search feature isn't so bad- it will find plenty for you to use.
Briefly, and by no means all-inclusive, what you're going to need is:
Early A V-8 throttle pedal linkage (your slant 6 linkage is a pivot rod type that won't work with a V-8)
Early A 273 motor mounts and brackets, which will need to be slightly modified to fit the 360.
Early A V-8 "drop center" steering center link.
A body kickdown linkage compatible with whatever carburetor you'll be using- 2bbl, 4 bbl.
A 22" radiator with the lower outlet on the passenger side (commonly found on '70 & up A bodies) and shroud.
Modify your wiring harness to accommodate the electronic ignition ECU and electronic voltage regulator that your 360 uses.
A 360 passenger car oil pan, pickup, dipstick and tube if your 360 doesn't already have them.
Exhaust is a cluster f*** on 360 early As- if you have manual steering, 340 ($$) and Magnum manifolds can be made to work, with some column modifications, but that will eliminate the ability to retain your column shift linkage, if you want to keep it.
Headers are pretty much Doug's and TTi, blow the cobwebs out of your wallet.
If you have power steering, you're pretty much limited to the Doug's, I believe, and the factory early A 273 manifolds. The problem with the 273 manifolds is that they're very restrictive, especially on a 360; the ports are considerably smaller. And there's a fitment issue with later 360 heads in that there's interference between the manifold downleg and the port pad on the #7 cylinder that may require a spacer (usually a bare header flange) to allow it to clear.
Either way, you will need to drill, tap, and plug the air injection holes next to the 360's exhaust ports.
Dual exhaust will require notching the transmission crossmember.
Your slant 6's 904 shift linkage should swap right over to the new trans. and work fine, as will the speedometer cable and driveshaft.
Seriously consider upgrading your 7 1/4 rear end, as well as your little 9" brakes.
Start searching and reading. This is just some basics and I know I've forgotten some stuff...
 
Last edited:
You need to sit down and start reading, the search feature isn't so bad- it will find plenty for you to use.
Briefly, and by no means all-inclusive, what you're going to need is:
Early A V-8 throttle pedal linkage (your slant 6 linkage is a pivot rod type that won't work with a V-8)
Early A 273 motor mounts and brackets, which will need to be slightly modified to fit the 360.
Early A V-8 "drop center" steering center link.
A body kickdown linkage compatible with whatever carburetor you'll be using- 2bbl, 4 bbl.
A 22" radiator with the lower outlet on the passenger side (commonly found on '70 & up A bodies) and shroud.
Modify your wiring harness to accommodate the electronic ignition ECU and electronic voltage regulator that your 360 uses.
A 360 passenger car oil pan, pickup, dipstick and tube if your 360 doesn't already have them.
Exhaust is a cluster f*** on 360 early As- if you have manual steering, 340 ($$) and Magnum manifolds can be made to work, with some column modifications, but that will eliminate the ability to retain your column shift linkage, if you want to keep it.
Headers are pretty much Doug's and TTi, blow the cobwebs out of your wallet.
If you have power steering, you're pretty much limited to the Doug's, I believe, and the factory early A 273 manifolds. The problem with the 273 manifolds is that they're very restrictive, especially on a 360; the ports are considerably smaller. And there's a fitment issue with later 360 heads in that there's interference between the manifold downleg and the port pad on the #7 cylinder that may require a spacer (usually a bare header flange) to allow it to clear.
Either way, you will need to drill, tap, and plug the air injection holes next to the 360's exhaust ports.
Dual exhaust will require notching the transmission crossmember.
Your slant 6's 904 shift linkage should swap right over to the new trans. and work fine, as will the speedometer cable and driveshaft.
Seriously consider upgrading your 7 1/4 rear end, as well as your little 9" brakes.
Start searching and reading. This is just some basics and I know I've forgotten some stuff...
That's a damn good start
 
Not sure if this was covered, and first I thank Professor for taking the time in this thread, the search system is indeed your very best friend.
Ok, back to one thing I will say, is the 727 transmission is a bit to large and your tunnel will need some messaging, the 904 fits .
 
I believe he's got a 904 on the 360- but that could be a lockup? trans and depending if it's a 999 or a 32RH it could introduce additional wiring mods to accommodate the tow/haul switch, and clearance grinding on the tailshaft reinforcement ribs if a 32RH. But there's another story... :)
Can 'O Worms.
Best/easiest/cheapest would be to just warm up the slant and have some fun, instead of taking the chance of turning it into a garage ornament.
 
I believe he's got a 904 on the 360- but that could be a lockup? trans and depending if it's a 999 or a 32RH it could introduce additional wiring mods to accommodate the tow/haul switch, and clearance grinding on the tailshaft reinforcement ribs if a 32RH. But there's another story... :)
Can 'O Worms.
Best/easiest/cheapest would be to just warm up the slant and have some fun, instead of taking the chance of turning it into a garage ornament.
Yep! ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
I believe he's got a 904 on the 360- but that could be a lockup? trans and depending if it's a 999 or a 32RH it could introduce additional wiring mods to accommodate the tow/haul switch, and clearance grinding on the tailshaft reinforcement ribs if a 32RH. But there's another story... :)
Can 'O Worms.
Best/easiest/cheapest would be to just warm up the slant and have some fun, instead of taking the chance of turning it into a garage ornament.
Yup, or, get a '66 V8 parts car to do the changeover, or, just buy a '66 Dart with a V8 already in it.
 
The stock 360 has so much low-rpm power (compared to other stock SBMs that in your lightweight-A, you won't actually need true duals, nor even headers. But if you go that way, and take advantage of the 360's torque, then at least, you won't need large diameter pipes.

Furthermore, for a streeter, if you leave the cam stock, It is possible, with the right combination of cooling system parts, to use the factory 6-cylinder radiator ......... a thing that I have successfully done with even a high-compression 340 using a 318 cam.

However, all that torque, if you use it regularly is eventually gonna smoke the 904 ............ so you might as well build it up now before you install it.
and
don't be peg-legging the 7.25 rear end. Either put a Limited Slip in now, or put fresh fluid in it, and take it easy on her. If you drive it like it still had the slanty in it, it will last at least as long as if the slanty was still under the hood. lol.
Sooner or later, yur gonna wanna floor that 360, and the peg-legging 7.25, is gonna give up the ghost. If it spits the cross pin out, and jams up the case, the rear tires will stop turning. when that happens at speed, you loose your steering. If that happens in traffic, that will Not be good.
If yur lucky, the spiders will just seize onto the crosspin and then you have a spool!
and
unless yur idling around every where you go,
yur gonna need more rubber. Those skinny donuts are gonna get you into so much trouble.
BTW
nice car
 
Thank you this is great information! On the topic of 273 exhaust manifolds, is there any way to get more flow out of them? That might be the only option as I don't have the money for headers.
You need to sit down and start reading, the search feature isn't so bad- it will find plenty for you to use.
Briefly, and by no means all-inclusive, what you're going to need is:
Early A V-8 throttle pedal linkage (your slant 6 linkage is a pivot rod type that won't work with a V-8)
Early A 273 motor mounts and brackets, which will need to be slightly modified to fit the 360.
Early A V-8 "drop center" steering center link.
A body kickdown linkage compatible with whatever carburetor you'll be using- 2bbl, 4 bbl.
A 22" radiator with the lower outlet on the passenger side (commonly found on '70 & up A bodies) and shroud.
Modify your wiring harness to accommodate the electronic ignition ECU and electronic voltage regulator that your 360 uses.
A 360 passenger car oil pan, pickup, dipstick and tube if your 360 doesn't already have them.
Exhaust is a cluster f*** on 360 early As- if you have manual steering, 340 ($$) and Magnum manifolds can be made to work, with some column modifications, but that will eliminate the ability to retain your column shift linkage, if you want to keep it.
Headers are pretty much Doug's and TTi, blow the cobwebs out of your wallet.
If you have power steering, you're pretty much limited to the Doug's, I believe, and the factory early A 273 manifolds. The problem with the 273 manifolds is that they're very restrictive, especially on a 360; the ports are considerably smaller. And there's a fitment issue with later 360 heads in that there's interference between the manifold downleg and the port pad on the #7 cylinder that may require a spacer (usually a bare header flange) to allow it to clear.
Either way, you will need to drill, tap, and plug the air injection holes next to the 360's exhaust ports.
Dual exhaust will require notching the transmission crossmember.
Your slant 6's 904 shift linkage should swap right over to the new trans. and work fine, as will the speedometer cable and driveshaft.
Seriously consider upgrading your 7 1/4 rear end, as well as your little 9" brakes.
Start searching and reading. This is just some basics and I know I've forgotten some stuff...
 
The stock 360 has so much low-rpm power (compared to other stock SBMs that in your lightweight-A, you won't actually need true duals, nor even headers. But if you go that way, and take advantage of the 360's torque, then at least, you won't need large diameter pipes.

Furthermore, for a streeter, if you leave the cam stock, It is possible, with the right combination of cooling system parts, to use the factory 6-cylinder radiator ......... a thing that I have successfully done with even a high-compression 340 using a 318 cam.

However, all that torque, if you use it regularly is eventually gonna smoke the 904 ............ so you might as well build it up now before you install it.
and
don't be peg-legging the 7.25 rear end. Either put a Limited Slip in now, or put fresh fluid in it, and take it easy on her. If you drive it like it still had the slanty in it, it will last at least as long as if the slanty was still under the hood. lol.
Sooner or later, yur gonna wanna floor that 360, and the peg-legging 7.25, is gonna give up the ghost. If it spits the cross pin out, and jams up the case, the rear tires will stop turning. when that happens at speed, you loose your steering. If that happens in traffic, that will Not be good.
If yur lucky, the spiders will just seize onto the crosspin and then you have a spool!
and
unless yur idling around every where you go,
yur gonna need more rubber. Those skinny donuts are gonna get you into so much trouble.
BTW
nice car
Thanks! What cooling system parts would I need to potentially maintain the factory radiator?
 
Some porting and smoothing can help a bit. Extrude honing can do a bit more, but, it's expensive and only helps just so much. You get the casting thinner and then you start having crack problems. Anything bigger than a 318 and I'd recommend headers if you plan on getting high RPM's. If it's just a street car and never sees 5k, the stock manifolds will work fine for flow. It's the ports sizes that can be a problem if you use 340/360 heads. The gasket tends to blow out easily, and depending on which casting you use, #7 exhaust port area can interfere with the manifold casting. Either the head needs to be ground on to remove extra metal (a delicate and risky job), or an extra spacer made (like a header flange) to bring the manifold out a ways to get clearance. If not, you try bolting the manifold down and it will break.
 
What radiator is in it now? If it's a 22" 2 row, it can be made to work if you make custom hoses, or, have different necks soldered on the the tanks. I would prefer to go to a 3 or 4 row core, but, I don't think a 4 row will fit a stock tank that year without some sort of modification. If you're not concerned with keeping it stock looking, an aftermarket aluminum one would be the way to go. If you have a 19" radiator now, forget that and get a bigger one.
 
Thanks! What cooling system parts would I need to potentially maintain the factory radiator?
i would strongly recommend replacing your stock radiator and upgrading the cooling system.

the stock radiator is tiny and satisfactory for cooling a /6, not a small block. even lowly 273 2bbls got a bigger radiator. also, the inlet and outlet will be in totally the wrong place (potentially), and that makes it a giant pain in the dick to get the radiator hoses right and generally you'll just wind up with some cobbled together mess of cut up elbows, lengths of pipe and a dumb accordion looking hose trying to make it all work.

so much easier to roll into the parts store and say i need a upper radiator hose for [blank] and not only do they have it, but it fits.
 
Some slant 6's (mostly A/C cars) came from the factory with 22" radiators too (part number 2582929). Some had 3 row cores too, which would be even better than the standard cooling (2 row core) that came with the 273. They could be used with a V8 by changing the inlet and outlet connections (and their locations) on the radiator tanks. Any good radiator shop should be able to do that. The factory A/C slant 6 cars came with a shroud too, but, those don't fit a V8 without some serious cutting and modifications due to the fan location between the two engines.
 
Switching to a 360 in an early A from a slanty, is a whole new ball-game.
BTW
IMO, the hands down best solution to the exhaust system, is the IIRC5204 Hookers which split the primaries on the Driver's side to two down the inside and two down the outside, of the frame rail.
Second best would be the 340 HO manifolds of yesteryear............... but they are not any cheaper than the headers.

To me, it sounds like, you should probably sit down and re-evaluate your budget.
Successfully converting a slanty A-body to V8 power is not cheap in the first place, and a 360 into an Early A is even less not cheap. And! And living in California is super not cheap, either.
Better it is to find this out now, than after you have spent your life-savings on the project, and suddenly find out it wasn't even half enough.
AFAIK, 360s never came with 904s, so if yours comes with one, it is not off a 360 nor a 340. That just leaves a 318/273. And if that is what you have and it has not been upgraded to put up with the biggest smallblock Mopar ever designed, then it just a matter of time before it fails.
Similarly, the 7.25 while not made of glass, it is still a ticking time bomb. As is the wiener drive shaft, the cooling system, the fuel system, the ignition system, the brakes/suspension/ and steering, and on and on.
If yur already balking at the exhaust system for lack of financing, I see where this is going.
stuffing the engine under the hood is the cheapest part.
I hate to be the one to say this out loud, but somebody's gotta manup and be the bad guy, and it might as well be me.. When I did that same idea but into a later A, I'm into it for well over $10,000 thousand Canadian, just on the powertrain, which doesn't include extras like the Edelbrock heads or the GVod, nor any body/interior work, nor wheels and tires, nor any labor, which I do myself. From there it only gets exponentially more expensive.
What happens if the engine dies three weeks after you put plates on it? Or the Trans. Or worse if you crash it because the skinny tires and 9"drums couldn't get you stopped in time, or that stinking right front spindle snaps off, as two of mine already
did when I was in my twenties back in the early seventies, I was lucky, the damage was minimal.
 
Ok, so from what i'm getting is that i'm a little in over my head in terms of 360 swapping the dart. If the slant already in the car turns out to be rebuildable, what can I do to it to get it over 200hp? And with what budget would this be achievable?
 
Ok, so from what i'm getting is that i'm a little in over my head in terms of 360 swapping the dart. If the slant already in the car turns out to be rebuildable, what can I do to it to get it over 200hp? And with what budget would this be achievable?
it really boils down to what your level of mechanical skill and resources are. if this is your first old car and first mopar, then it might be deep waters for you. not saying it can't be done, but without traveling that road previously you'll be out of your element.

just doing up a motor can easily be 3~5 grand, throw a transmission in there too so add at least another 1K easy money. then all of the peripherals: wiring, cooling, mounts, exhaust and it starts to add up quick-- the money and the work. then throw in the complexity of an early A body and that just takes the difficulty factor up another notch, along with the cost of doing business.

if it's your dream car, and you have another daily driver, and you've got 10K to blow? sure, go nuts. just don't forget to budget for brakes.

as for hopping up the six, tons of performance parts around. they respond well to the usual hot rod treatment of better exhaust and intake and bigger carbs. personally, i'd KISS and just hunt down a supersix (or other 2bbl) intake, get a header, and throw a cam at it. unless the motor needed a rebuild, that is.

then i'd turn to brakes and suspension knowing anything that i upgrade could potentially compliment a V8 swap down the line.
 
There are plenty of Mopars that have 904's behind a 360 from the factory. Not rare at all. Most car models in the mid-late 70's had that option. Pickups and vans all came with a 727 though.
 
people, have a tendency to chase a specific horsepower level, which, for racing, once you get into top gear, you gotta.
Read this and skip the rest;
The quickest way to performance, on the street, is with stall and gears.
For a streeter, horsepower per se, isn't all that important. Because, you have a transmission, which multiplies the torque, that makes the horsepower.
For a streeter, that is usually limited to rear gearing that is suitable for occasional highway cruising, yur gonna find out real quick, that you are only ever gonna get to where the power is, just once, before the car will be speeding.
Just suppose you did build your slanty to 200 hp. This would come at around 5000 rpm , or higher.
If you stuck with 2.76 rear gears and 25" tires, with an automatic, THEN, this will come at about 50 mph using the A904 and assuming 10% slip in the convertor.
When you shift at 5000, the rpm will drop to 2950, and the poor slanty, or any engine with a Torqueflite trans, is stuck in slow mode, and won't be coming up for air until say 4000 rpm, which for you, will be 67mph.
So now, your 200 hp engine has been seen only once; and briefly, in first gear, from say 4000 to 5000 rpm, which is from 40 mph to 50mph.
Is that what you want in a streeter?

Well it was sure not what I wanted!
I wanted to smoke the tires in second gear at 50 mph when I pulled out to pass some hiway-tortoise, and I wanted those tires to keep on smoking when I screamed by him/her looking him right in the eye, at 85 mph. Oh yeah. and
I wanted to leave it in second gear in the city, and slide my car around as many corners as I encountered. Great big beautiful drifts, with the engine screaming for mercy at up to 7200 rpm.
For that; 2.76s were out.
And 2.76s will be out for you as well.

So if horsepower on the street is not the target, then what is?
Horsepower is fun, I'm not kidding, but any time the tires are spinning, you basically have more power than you need.
In first gear, my tires will break loose at less than 2000 rpm, still on the primarys; and once spinning, I can slowly close the throttle to just above idle. She will continue churning like that, with the line-loc applied, all the way down to IDK, certainly under 1200 rpm. She's a real crowd-pleaser. The point is this, my engine already has more than enough horsepower at 1800 rpm, to break those tires loose;and whatever more it has, is overkill.

Ok then lets figure this out; Lets say my engine easily makes 20 hp at 1800 rpm to break traction. the formula for making horsepower is
(Torque times rpm)/5250= hp
so to extract the torque from the horsepower, we re-arrange it to look like,
(hp x 5250)/rpm=torque; and so, (20x5250)/1800=58 footpounds.
Ok; But I have a 3.09 low gear in my manual trans and a 3.55 in the back, so the rear axles are actually seeing;
58 x 3.09 x 3.55 = 636 ftlbs, and I have 27 inch tall tires, so the contact patches are seeing (24/27) x 636= 565ftlbs.
Ok then, knowing what it takes to break loose, two hard 295/50-15s ; we could now apply that backwards to your combo.
To make this easy, I'll say your tires are 24" tall, your gears are 3.23s your low gear is 2.45, and your tires are half as wide as my 295s cuz that is all you can fit into your tubs. With half as much rubber, you'll only need half as much torque, so looking for say 300 at the tires. therefore;
300/(3.23 x 2.45) = 38 measely crank ftlbs. Piece of cake! , all we have to do is rev the motor up high enough to find 38 ftlbds, and you will be spinning two 5" wide tires, x 24" tall.
Suppose your slanty makes that at 2200 rpm, then all you need is to install a convertor that stalls at 2200 rpm or more; You don't even have to touch the engine!
And that makes my point. which is this;
The quickest way to performance, on the street, is with stall and gears. This is especially true as the engine gets smaller, and is physically handicapped by things like a low compression ratio, poor flowing heads, a tiny exhaust, and a stinking 1-bbl carb, lol.
Personally, for your combo, I like a 2800 and 3.73s. For about a grand, if you can find gears, for the 7.25, you can be having a blast............ but don't try reving the old girl to 5000. The valvesprings, in my experience, are done at about 4500.
The neat thing about 3.73s and 4500 shift-rpm, is that first gear tops out at about 33 mph now, and second at 56, so your engine is gonna go thru the stock power peak twice!
And the 2800stall will rocket off the line when combined with the 3.73s.
and, the engine is still the anemic, what were they in those years? 145 hp?
So then, one more time, for effect
The quickest way to performance, on the street, is with stall and gears.
 
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