Hot rod mag is pretty good about their tech stuff. If anything, I'd sell both 318s and start with a 360. You get more out of it doing the same stuff and it will cost you about the same as a 318. They are all over the place. heck a guy with a 360 motor in his 80s-93 truck might be willing to trade with you.

Do you plan on making this truck work at all for you? if so then keep the 318.

 

Here is what I would do. Pull the motor that you have and throw in the good one. Then rebuild the one that you pull out how you want. You will have to bore the motor to get 400HP but there should be plenty of sidewall clearance. I wouldn't bore the motor unless you have to though. If you want reliable, then maybe look into a TBI setup instead of carb. If you go carb, get one with an electric choke.

You may also want to upgrade the tranny some (valvebody, shift kit, torque convertor). Don't forget about the rear axle also.

 

ported and polished *302 heads with 2.02 intake valves and 1.88? exhaust valves (should give you a 11 to 1 or better compression with flat top pistons, cam, flat top pistons, small 4bbl carb. if you are going to use it off road id go with 500 cfm or smaller. bigger carbs seem to make you lose torque. headers...

 

tbis are quite expensive for the conversions. just go on summitracing and you can narrow the search between electric and manual chokes. probably just an edelbrock performer 500cfm

 

but you probably arent going to get around 400 without boring it out. i would go .020 or .030 just in case you decide to rebuild it in the future and it needs another rebore. im in the process of rebuilding a 318 and one thing i did was use a dremel to bore out all of the oil pathways to provide better flow. soon its going to a shop to get rebored probably .020 over then getting the forged 340 crank

 

Great article from Hot Rod, lots of good info there..
But remember - you won't get those HP numbers unless you work the heads like they did,
and I wouldn't think the Edelbrock AirGap manifold & 1-inch carb spacer would be what you'd want
for towing & hauling purposes..
I'd say follow their build but forget the AirGap mani & carb spacer (and make 375 HP at the flywheel -
not too shabby!!! and a huge step up from where you are now).
Just don't over-carb it! or you'll have a total slug on your hands.
I wouldn't put anything bigger than a 600 cfm vac secondary carb on it!

You have the 318's, so use the 318's
(Murphy's Law predicts you will fall ***-backward
into a 360 shortly after you finish the 318 build though lol).
But so what? 318's can indeed make good power!
and get respectable mileage when tuned & set-up correctly.
318's were never really marketed as true "Hi-Po" engines back in the day,
and then the de-tuning for emissions
really seemed to cement their reputation as "dogs"..
But if you ever drove an old ('67 - '71, IE: Pre-Emission) 318, you'd know that even in stock trim
they make a surprising level of power and don't mind revving,
even w/ the restictive heads, and they really wake up once you let 'em breathe
thru a small 4 bbl & low-restriction exhaust..
Speakin of exhaust, forget the typical "cherrybomb"-type of straight-thru glasspack -
they sound great, but beleive it or not, have more back-pressure than you think
(thus robbing power - dyno tests prove it).
For a far less restrictive exhaust set-up, run a set of old Cadillac resonators (mid '60's thru late '70's)
- not the mufflers, just the resonators. And be sure to have a crossover pipe (H-pipe) in the exhaust,
for more "free" HP and torque.
The above exhaust set-up not only frees up power, but sounds great as well - deeper-toned,
but not obnoxious lol (and run a clutch-fan too, for more "free" HP)

There's my 2 cents worth on it lol..

Good luck with your build!

 

edelbrock is always a safe bet

 

X2, I agree..
the following combos could work for your 318 -

Option 1

I found the following on the Summit Racing website:
Part Number EDL-2176
Intake Manifold, Edelbrock Performer, Dual Plane, Aluminum, Natural,
Square/Spread Bore, Chrysler, 318/340/360
$209
With either of the following carbs:
Summit Racing Street & Strip Carb
600 CFM Vacuum Secondary, electric choke, squarebore Carb
(Summit Brand Holley-type design)
$225
OR
Edelbrock Performer Carb
600 CFM Vacuum Secondary, electric choke, squarebore Carb
$300
Or
Holley Street Avenger 4160 Carb
670 CFM Vacuum Secondary, electric choke, squarebore Carb
(comes w/ different vacuum secondary springs for tuning -
different secondary springs will "size" it to your engine,
so don't worry about the 670 CFM rating)
$380

I listed the above separately because the Edelbrock Manifold/Carb
Combo Pack that Summit features comes with an RPM Air-Gap intake
and an 800 CFM Carb and lists for $875..
I still don't think you need that much carb/intake
for the way you intend to build and use your 318..
but senseless overkill can be yours for only 875 bucks lol
(just don't blame me if it don't run worth a damn lol)

If it were me, choosing from the above parts, I'd probably get the
Edelbrock Performer Dual Plane aluminum intake
and either the Edelbrock Performer Carb
or the Holley Street Avenger 4160 Carb.
I have experience setting up and tuning each type,
I think they're easy to work on.
The Summit Brand carb looks like a design copy of the Holley -
if so, it too should be very easy to set up & tune to your application.

Of course, you will need all the gaskets, fasteners
and other miscellaneous items to finish the installation..


Option 2 might be a Summit Racing Brand aluminum Intake & Carb
Combo Pack
Part Number Summit 03-0204
Summit® Intake Manifold, Carburetor, and Air Cleaner Value Packs

It includes:
Summit Racing Street & Strip® Stage 1 Intake Manifold
Intake Manifold, Stage 1, Dual Plane, Aluminum, Natural,
Spread/ Square Bore, Mopar, Small Block 318, 340, 360
And a
Summit Racing Street & Strip® Carburetor
600 CFM Vacuum Secondary, electric choke, squarebore Carb
(Summit Brand Holley-type design)

PLUS all the gaskets & fasteners you'll need
And a chrome open element air cleaner..
$435

hmmm, all things considered, I might try this combo myself on my 318..
(though I prefer to run spreadbore carbs on my V8's)

Remember, no matter what you decide to get,
all carburetors perform best once they are set-up, tuned and tweaked
to your specific application (IE: Power Valve, vacuum secondary opening
point and rate, accelerator pump shot and volume, jetting,
position of throttle butterflies at idle, full linkage travel, etc).
Don't let any of this intimidate you - you may be satisfied with the way
it runs right out of the box -if so, cool.
If not, the new carbs come w/ info and there are plenty of books
and info online to help you set-up and tweak a carb..
Plus, the process itself can be very enjoyable
and very satisfying, in my opinion..
It's a great feeling to take a car that idles poorly or stalls or stumbles
or bogs out and turn it into a rocket, with strong, crisp, instant throttle response,
with the accelerator pump & power valves & secondaries all kicking in right on cue,
knockin ya back in the seat as the engine roars
and the scenery starts rushin by real quick..

aw man, the hell with sittin here at the computer -
I'm firin up the ol' Dodge & hittin the street !!
God bless America and Walter P Chrysler
If you hear a screamin V8 and smell tire smoke
don't worry - it's just me & my old Mopar

 

 

Didn't the Hot Rod build suggest a cam (or so I thought)..?
In any case (and some may disagree)
but I have always liked to use a good-quality
double-roller timing chain/gearset,
and install a 2 degree offset key at the crank gear
(for 4 degrees advance at the cam).
Two reasons for this -
1) a little advance helps in the lower portion of the rpm/power band
(which i think you'd want since you say you plan to haul & tow
w/ the truck).
2) it helps compensate for the eventual wear and slack in the timing chain

No, the Hot Rod build doesn't mention doing this, but then they were
seeking ultimate top-end power, not real-life usable hauling & towing power lol..
A number of damn good old-school engine builders have told me about
this 2 degree advance trick over the years..
I've always done it & never regretted it.
Just more food for thought for ya