Myself, I probably wouldn't do a 340 /360 swap if I already had a 318. To do the swap there's the expense of buying the other engine, 360's are balanced differently so there's the extra cost of a converter LA 360's. The motor mounts are different than the 318's. I'm not complaining about the cost, just stayed what's involved.
Dan I gotta tell you, if your 318 needs pistons, and your car is pushing 3600 pounds with you in it , choosing to stay with the 318, over choosing a 360, is, IMO, false economy.
By the time you get the 318 up to pressure, and the chassis set up for the new power curve, it very well couldda cost you LESS if you had just started with a locally sourced 360. And there's just no comparison in the torque.
For your application;
the 360 cam, if it's half-decent, is already close to perfect
you could easily get away with using the 318 heads, and sell the 360 ones.
You can even bolt on the entire 318 top-end. I mean everything from the decks up.
All your 318 stuff will bolt on to the 360.
The engine mounts are a non-issue.
The convertor is a non issue. One phone call and whatever you need is on the way.
The 318, to make your requested 300hp, is gonna need the following parts. How much are these additional parts gonna cost?
As to the engine;
>High compression pistons
> a cam kit, to move the power production some 600 or more rpm higher.
> headers,
> a 4bbl intake, carb, and filter box
Those are the basics.
as to the chassis:
Additionally, to make use of this potential, at a roadspeed where it counts, the chassis is gonna need;
the following upgrades
>a higher stall TC
>a bigger rear gear, and the install of it
> dual exhaust.
So lets add up the additional stuff for the 318
Extra cost pistons and and possibly lots of decking, along with decking comes milling the intake interface, the cam-kit, the induction system, the convertor and the installed gears, plus headers. This is all extra cost over the basic.
I'm gonna guess this is gonna add up to over $3500, over the basic rebuild.
Now, what will the 360 need?
Well I'm going to suggest that horsepower for your application is relatively meaningless cuz the worn out 360, with a 4bbl and dual exhaust, changes that yur already gonna need to do with the 318, even just plopped into your car as is, will likely already do all that your 318 will do after having spent a ton of money on the combo. But Ok let's look at it
As to the 360 engine;
>High compression pistons, nah KB 107s will do it.
> a cam kit, nah the 360 2bbl cam is already 400 rpm higher than the stock 318
> headers/ nah, Ok lets get some 340 logs.
> a 4bbl intake, carb, and filter box, nah just run the big 2bbl
Those are the basics.
as to the chassis:
Additionally, to make use of this potential, at a roadspeed where it counts, the chassis is gonna need
the following upgrades
>a higher stall TC, nah
>a bigger rear gear, and the install, nah
> at least dual exhaust. Yeah that will be needed.
Ok so, the only additional cost is the pistons if your core needs a rebuild.
That plus, the 340 logs/or headers, and dual exhaust are needed in both cases.
So then the 360 costs are;
The core, the flexplate, and the KB107piston-kits if the engine is worn out, and the 340 logs. All other rebuilding costs will be the same except a lot less machining. So let's call it $1500 over the basic. not even considering the machining savings.
A difference of $2000 LESS money, to make the 360 into a decent runner....... including the cost of the core.
I'm gonna say it one more time;
if you are on a tight budget;
Leave the 318 alone. Just slap a 2800 TC into it and about 20/25% more rear gear, up to 3.55s if hiway travel is an occasional thing; and call it done. Yur 318 combo is gonna need that stuff anyway, so you might as well start there.
If fuel mileage is a concern, then top it out at 3.23s, and chose a lightweight, short wheelbase car, like a Scamp, or Valiant. Just keep in mind that the rear tubs on those cars will only accept up to 255s.
If yur thinking bigger some day, then you will need a 2-door sportback; like a Duster, a Demon, a Sport or a 789 Barracuda. All of these will swallow 295s with ease. Or, you know, an early Dart, a Valiant wagon, an F-body, a Toad, or a lowered early Dakota.....
Keep on dreaming my friend, I can do this all day every day. I actually like doing this all day, lol.
