Today, dollar for dollar, is the 318 faster than the 340 ???
These threads are always kind of silly. You couldn't give me a 318, even just for a "peppy" street motor. About 12 years ago had a '71 Dart with a bone-stock 318 2bbl. It could actually smoke the tires easily, made some torque but would not rpm past 3,500-4,000, tops. Took it to the track in this form once just for fun, ran a 17.67 1/4 mile at like 71 mph or something. I was laughing all the way down the track, like c'mon Nelly! Shifting myself it picked up a little, maybe a hundredth. You'd be foolish to argue that any bone-stock 340 car will go low 15s without trying. Tune it up and get it to hook, you could be in the 13s without too much effort.
I've stated my opinion on this before but I'll say it again, its not worth spending money on a 318. The 318 was never intended to be a performance engine from the factory. Even the 273 had the Commando package for a few years but to my knowledge there was never a 318 package like that. That should give some insight into the root of this discussion.
The 318 was your garden-variety basic transportation passenger car mill. Pull any model year out of a hat and check the 318 specs.; they were all low compression, were alnost always 2bbl equipped and placed in front of a basic 904 with 2.94 open rear ends in low-level couples and sedans. Thrifty secretary cars.
That said, can a 318 be built to perform? Sure, why not? It's an engine, just like a 340, 360, 440 etc. Throw enough money at it and maybe you'll make some steam. Everyone knows heads and cams make power but how to enable that on a 3.9xx" bore? Sleeve the block and bore it to at least 4.00", that way you can run a decent size valve without shrouding. ($3k budget out the window) Without the extra bore size you're pissing in the wind because you'll never take advantage of heads that have any air flow potential.
Besides, whether it's a 318 or 340, building any engine for $3,000 is not realistic, speed costs money. So if you're going to spend some coin to go fast, (even if the block is free) why waste it on a handicapped platform? Unless you get free machine work done by a really experienced machinist, you're going to spend at least $1,500 to start. Boring with torque plates and honing to the correct finish, square decking the block, line honing the mains yada yada yada. Plus, whether you put them on a 318 or 340 block, any decent-flowing cylinder heads are going to cost at least $2K so IMO you're over $3K before you even put the thing together. If you have Ricky-racer parts 'laying around' that you're willing to throw at a 318 that's been sitting for years you've spent money to own that stuff already so there's no free lunch.
You can argue it's not the bore but why? Why handcuff yourself with a smaller bore when you can get a 360 and start with a 4.0" bore. OK, some LS motors that the whole world loves are less than 4.0" bore but that's not a fair comparison, those are modern engines with way more sophisticated controls, aluminum parts and roller cams.
Another small cubic inch motor that often seems to get thrown into these discussions is the Ford 302. Even though it's less cubic inches, the 302 has the magical 4" bore. Sure a good many of them were lo-po stump pullers in trucks but the 5.0 Mustangs were pretty good performers for what they were. Pretty hard to argue that your basic '80's 5.0 Mustang wouldn't smoke any factory 318-equipped muscle-era Mopar. Don't even argue that, it's not worth the bandwidth. Maybe ask Tony Defeo about it.
Even de-stoked the 4" bore will always make more power. Tell me what you think about the car in the video below. It's 292 cubic inches which is a de-stroked 302 so it's got a 4.+xx" bore. This is a quick car no matter how you slice it. Yeah, it's a high compression race car but for comparison sake you just don't see this type of combo with a 318. Guy revs the piss out of this thing, must be 9,000 rpm, insane.
