74 Dart 318 to 383 Engine Swap Help

-
tristanbngl

tristanbngl

Member
Joined
Aug 30, 2017
Messages
9
Reaction score
0
Location
cypress, california
I bought my first car not too long ago, a 74 dart with a 318/904, i'm picking up a 383/727 later today for a steal and was wondering what i would need to do to make the swap work. Also, what'd be the major difference in power after the swap. I was going to just put a four barrel carb/intake and headers and exhaust for more power in the 318. But now with the 383 im assuming it shouldn't be too hard to get the power i wanted to get with the 318.
 
tristanbngl said:
I bought my first car not too long ago, a 74 dart with a 318/904, i'm picking up a 383/727 later today for a steal and was wondering what i would need to do to make the swap work. Also, what'd be the major difference in power after the swap. I was going to just put a four barrel carb/intake and headers and exhaust for more power in the 318. But now with the 383 im assuming it shouldn't be too hard to get the power i wanted to get with the 318.
Click to expand...
you're gonna need the following:

Bigger Radiator
Schmaucher Mount kit
Disc Brakes
a minimum of 1.03 torsion bars.
at least a 8.25 rear axle, preferably a 8.75 or dana 60
Better shocks.

as for power, 383 has way more than a 318. it'll be easy to push 350-400 hp flywheel with simple mods like headers/intake/carb
 
dukeboy_318 said:
you're gonna need the following:

Bigger Radiator
Schmaucher Mount kit
Disc Brakes
a minimum of 1.03 torsion bars.
at least a 8.25 rear axle, preferably a 8.75 or dana 60
Better shocks.

as for power, 383 has way more than a 318. it'll be easy to push 350-400 hp flywheel with simple mods like headers/intake/carb
Click to expand...
and tools - lots and lots of tools
 
ScampMike said:
in which case - save the $$ you're about to spend on the 383 and warm up that 318 - learn to walk before you try to run
Click to expand...
that's what i was thinking as well, i have an 600cfm edelbrock carb that's waiting for an intake manifold how much of a difference would you say it would make towards my stock 318 with a 2 barrel carb
 
tristanbngl said:
that's what i was thinking as well, i have an 600cfm edelbrock carb that's waiting for an intake manifold how much of a difference would you say it would make towards my stock 318 with a 2 barrel carb
Click to expand...
just swapping an intake? roughly 25-35 hp give or take
 
tristanbngl said:
that's what i was thinking as well, i have an 600cfm edelbrock carb that's waiting for an intake manifold how much of a difference would you say it would make towards my stock 318 with a 2 barrel carb
Click to expand...
you really need to talk to @Kegan B hes about your age and just did a real nice job himself on his 318 scamp
 
I like big block A bodies but have to agree, start with the 318 and learn the basics. Meanwhile keep that 383 oiled and wrapped up in the corner.
 
tristanbngl said:
I'm also still a teenager trying to save as much money as i can.
Click to expand...

Cheap, fast and reliable. Everything you said in this thread can be summed up with those three words. However, it is impossible to have all three. It's only possible to have 2 of the 3 words. Which 2 do you want?

Dropping a big block into an A body is not a cheap project. However, you clearly indicate you don't want/have a lot of cash to spend. As others have suggested, hop up the 318 and keep that big block in the corner until you have the time and funds to do the project.
 
dukeboy_318 said:
you're gonna need the following:

Bigger Radiator
Schmaucher Mount kit
Disc Brakes
a minimum of 1.03 torsion bars.
at least a 8.25 rear axle, preferably a 8.75 or dana 60
Better shocks.

as for power, 383 has way more than a 318. it'll be easy to push 350-400 hp flywheel with simple mods like headers/intake/carb
Click to expand...
I swapped a 383 into a 67 fastback when I was 15 in 1977. no money and little skill, I learned a lot from that swap. I had an advantage though, a junk yard where I could roam and knowledge from books and mags. It is easier now, with the internet and available parts.
although the disc brakes and bigger torsion bars would be nice, they are not a necessity.
anyway, I had a motor/trans and a dream. I'm still fulfilling the dream and have the same 67 today.
Question is do you have the dream ?
 
To put the 383 in the 74 Dart, first is what rear do you have? Next you need to have the conversion motor mounts. The drive shaft will need to be shortened. That will get it in the car. Next you need a big block 3 row radiator. Last thing you will need is exhaust manifolds and exhaust for a big block. The factory used larger torsion bars, bigger sway bar, and had heavy duty rear springs and shocks. Since you now have 400 ft lb of torque good brakes would be good. Do you have front discs? The main expenses are the radiator and exhaust manifolds or headers.
 
I say a nice dual plane intake, a decent cam, headers and a 600cfm carb for the 318 and call it good.
 
I did the same. Start with a 318 and learn basics and then switch to BB. Why do you want a BB? What is your goal?
 
Kegan B said:
I say a nice dual plane intake, a decent cam, headers and a 600cfm carb for the 318 and call it good.
Click to expand...

Right now i have a edelbrock 600cfm carb waiting for an intake so it can all be put in. Would you recommend changing the rear end gears as well? For the most part it's stock.
 
tristanbngl said:
Right now i have a edelbrock 600cfm carb waiting for an intake so it can all be put in. Would you recommend changing the rear end gears as well? For the most part it's stock.
Click to expand...
Yeah, something like a 3.55
 
gears,
and higher-stall,2800
Ok: gears, 4bbl,2800TC, and headers with a free-flowing exhaust.
But I wouldn't put a cam in an LA, unless the compression was matched to it,or,if the car had like 3.91s(auto) or better.
and here's why;
With the stock 240* cam in at 110*
Static compression ratio of 8:1.
Effective stroke is 2.86 inches.
Your dynamic compression ratio is 7.04:1 .
Your dynamic cranking pressure is 135.24 PSI.
V/P (Volume to Pressure Index) is 111........................................111

Here is the same engine with decent compression matched to the factory cam
Static compression ratio of 9.1:1.
Effective stroke is 2.86 inches.
Your dynamic compression ratio is 7.99:1 .
Your dynamic cranking pressure is 159.62 PSI.
V/P (Volume to Pressure Index) is 132.........................................132 remember this for later

That's an improvement of 132/111=18.9% in low speed torque, just what a 318streeter needs. That's like a jump from 2.76gears to 3.23s. Or from 3.23s to 3.84s.

But say you put a bit of a cam in there with the stock optimistic 8/1 Scr.
Say a 252/112 cam like the 360 2bbl cam
Static compression ratio of 8.0:1.
Effective stroke is 2.78 inches.
Your dynamic compression ratio is 6.87:1 .
Your dynamic cranking pressure is 130.95 PSI.
V/P (Volume to Pressure Index) is 105........................................105
What just happened here? That's right, 105/111=94.6 you lost 5.4% of your already weak bottom end.
This 262*cam wants
Static compression ratio of 9.4:1.
Effective stroke is 2.78 inches.
Your dynamic compression ratio is 8.04:1 .
Your dynamic cranking pressure is 160.92 PSI.
V/P (Volume to Pressure Index) is 129.........................................129
But notice the bottom end is still a tad weaker than the stock cam at 9.1scr, which was 132.

But let's say you got greedy and put a 268/110 in there at 8.0Scr
Static compression ratio of 8.0:1.
Effective stroke is 2.66 inches.
Your dynamic compression ratio is 6.62:1 .
Your dynamic cranking pressure is 124.66 PSI.
V/P (Volume to Pressure Index) is 96
The ultimate what-the-heck did I do moment......................................96
What we have here is a total dog engine until the revs get up to about peak torque or I'm guessing, 3750RPM. So she's gonna want a BIG TC to get moving.
This 268*cam wants
Static compression ratio of 9.8:1.
Effective stroke is 2.66 inches.
Your dynamic compression ratio is 8.06:1 .
Your dynamic cranking pressure is 161.44 PSI.
V/P (Volume to Pressure Index) is 124..................................................124
And the bottom end is still weaker than the factory cam and 9.1 Scr, but it's something that you can deal with by using a higher stall

But Why do I harp on the VP and the bottom end?
Cuz in a 318 streeter, that should be priority one,IMO. And the reason for that is the factory rear gears, and the factory TC of about 1750. If you ditch these, then you stand a chance at performance.
But say you're stuck with 2.76s and the 1750, and 25.5inch tires.
20 mph will be about 1870rpm@5% slip. So if you don't have any torque there, like with the 268*cam/96VP cam fer instance, then you have a dog combo. Whereas the factory cam in the 9.1 engine has plenty of VP@132
So when you add all this up, to run a bigger cam, you basically might as well slam a 360 Magnum in there cuz it will do more for less money.
I mean bumping up the Scr to run a bit of a cam, leads to headwork, and a TC and gears and usually a complete 8.75 rear end plus a driveshaft. Since the trans is down, you might as well beef it up or at least freshen it up Money.money,money.
So that's why I say I wouldn't put a cam in an LA.

Furthermore, Since putting in a bit of a cam will absolutely require a bigger TC and gears, Why not just start there in the first place. If,at some future time, you decide that the teener just isn't doing it for you anymore, then at least you're ready for it.
As for me; the first thing I would do is gears.
Oh wait, I already did that once; 4.30s lol, and a 2800, and a big TQ, and TTIs and dual 3inchers all the way, And it fried the 295s. No cam no heads.
 
Last edited:
Instead of a 360, just save your coin and put your 383 in it, even better. No problem with putting a mild cam, 4 barrel, and dual exhaust in an A body. It will still be a nice running car, even with stock converter and 2.76 gears. How can I say this in the face of all that math? I have done it to my son's 73 4 door Dart. He loves it. 20 mpg at 70 mph all day long. Much better than the 2 barrel and small 318 cam.
 
tristanbngl said:
I found the BB for virtually dirt cheap. My initial goal was to beef up the 318
Click to expand...
From the sounds of it, your budget and knowledge may be a major factor in a BB swap.
Fabo member 318willrun is a guru when it comes to making power with the 318. Take a look at some of his threads and maybe contact him. he knows how to do it with a small budget. good luck
 
jpar is also known for 318 budget build. he is a cheap son of a gun. lol but he gets it done.
 
Do yourself a favor and stick with the 318. Hop it up a bit. Parts are dirt cheap and everywhere. Thennnnnn, while you drive it around read all you can about big block swaps, collect your parts, and slowly budget your motor, trans, rear, suspension and brakes. Yes it will fit, yes, it goes right in.
 
You must log in or register to reply here.
-

Back
Top