There was a Chrysler Windsor poly that used the Chrysler Hemi block with Poly heads. There was a Dodge poly that used the Red Ram Dodge hemi block. And there was the 318 type Poly that had its own block, no hemi version. The 318 was the base Dodge/Plymouth V8 in the late 50s/early sixties. Then in 1964 they made the LA 273 for the Valiant/Dart/Barracuda. They redesigned the 318 with skinnier heads and smaller bore pistons because the poly 318 would not squeeze into the A body cars. Then in 1967 they made the LA 318, basically the 273 with 318 pistons, which became the base V8 from then until redesigned as the Magnum engine in the early 90s.
In 1957 and 58 they had a killer 318 with 290HP and 2X4 barrel carbs. They dropped it as soon as they got the big B engine for performance and the 318 was relegated to base V8, sedan and station wagon duty. You couldn't even get a 4 barrel after 62. The next performance A engine was the 1968 69 340. This was a hopped up 318 made specially for hot Barracuda, Valiant and Dart use. Those were A body cars and only the small engine would fit. They had to have something to compete with the hot Mustangs and Camaros. After 1970 the Barracuda and Challenger were made on the B body platform and they could put in the big 440 and hemi engines. The 340 got put on the back burner and turned into the 360. This was a long stroke, torque and smog motor for full size cars. So you really only had those 2 years of LA engine hotness. But for those 2 years the 340 was the fastest small block around.
I guess one needs to define "race" to determine if a 318 is a good candidate to begin with. Guess we would also need to know what the 318 has to pull around in that "race". Would also be helpful to know what the "race" budget looks like. The cam in a 318 is a daily driver version and it way too small for racing. The factory 2bbl carb is very small and limits the amount of air you can get into the cylinders. The factory single exhaust system is too restrictive to move the spent gas away efficiently for racing. If you want to go faster, a bigger cam, a 4bbl carb, and dual exhaust are minimum things your going to need. The same money required to buy those items is the same money (and probably the same parts) required to make a 360 run even faster, but if you already have a 318 and not a 360, the 318 might make sense. I know I have made a few 318s run pretty hard. Your money, spend it as you see fit. Gene
Early Polys:Chr Hemi blocks were used for Chr Polys. Dodge Hemi blocks were used for Dodge, DeSoto, & Plymouth early Polys. The "318 Poly" type Polys(Late Polys) are "A" Polys, they came in sizes of 277, 301, 303, 313, 318, & 326.
340 was made 68-73. When Mopar needed a 305 for Trans-Am racing they destroked the 340 instead of the 318, making a big bore/short stroke combo like the Fords.
The "906" refers to the last 3 digits of the casting #. Then 906 head was used on all 383 and 440s there is no special "Magnum" head end of story. For any given year all 383-400-440 engines used the exact same head, the only difference being the 440 motorhome or heavy duty truck engines, but that is a different story all together.
383 had 906's as well, 2 barrel or 4 barrel. No special heads for magnums, better cams, 10:1 compression, better intake manifolds, windage tray, better exhaust manifolds, that was it. Doesn't take much to wake up a big block Mopar. Plus magnum cars had a bit looser torque converter, and usually at least 3.21 gears, many had 3.55-3.91. Big difference from a tight converter land yacht with 2.73's.
"The next performance A engine was the 1968 69 340. This was a hopped up 318 made specially for hot Barracuda, Valiant and Dart use. Those were A body cars and only the small engine would fit. They had to have something to compete with the hot Mustangs and Camaros." Well, you could argue pretty easily that the 273 was the next hi-perf A engine, at least the 4 barrel version with adjustable rockers, hotter cam, more compression, and finned valve covers. Then, there was the even hotter version used in the D/Darts but I'm not sure they were truly production vehicles. Stock for stock, a 318 Poly would and will walk all over a 318LA. As for 440's, the Magnums were great engines but you could take a regular 440 and add dual exhaust and get most of the guts of a Magnum. In other words, a properly tuned 440 would hang with a 440 Magnum that wasn't in the very best of tune. For every guy who had a 'real' 440 Magnum there were 4 guys who had 'converted' 440 Magnums. Either way they'd dish out the hurtin'.
Imperial, New Yorker, Town and Country wagons with 440, 4 barrel, dual exhaust got basically the same engine as the 440 Magnum. All the good parts except the HP cam. So if you spot an old Imperial, New Yorker or T&C rotting away in a junkyard check it to see if the engine is gone. If it's still there, its practically the same as a Charger,Super Bee or Road Runner HP engine at a friendlier price.
To get back to the original question, the most bang for the buck would be our own Don Dolmetch's Old Reliable 440 build. If that is too spendy you can get good performance out of a 360. I wouldn't even consider a 408 or other stroker. You could build a junkyard 440 or 400 cheaper and have a better engine with more HP. As for the 318 it is a good engine and can offer good performance for its size, but the bigger Mopar engines are too cheap and too easy to find. If the object is max HP for the bucks, there is no replacement for displacement.
Some issues with what you are saying here: The 340 was probably at it's hottest in 1971 with the big ass thermoquad on it, ask the super stock guys, so I would say it had a pretty good 4 year run, showing big blocks taillights a large portion of the time. The compression was dropped to 8:1 in 72, and in 73 it was fitted with a cast crank (which for the most part changes nothing in performance, but had an oddball balancer and torque converter/flywheel). In 74 the 340 cam and double roller timing chain along with the intake and carb were fitted to the 360 and the e58 was born. Given it's low compression, it was a pretty damn good performer, better than most of the crap coming out of detroit at the time. The e58 was optional in the last of the e body's, Dusters until the end ('76) and the F-M-J body cars into the 80's. It was also used in the Little Red Express trucks, the fastet U.S. production vehicle in '78-79 (not saying much, but still impressive).
I bought a 73 Challenger 340 new and even with the low c/r it was still plenty quick...and it was not a light-weight by any means. Also, don't forget about the E58 in the 1979 Chrysler 300 and the Magnum GT. I have had both (and wish I still had them...) and they ran hard everything considered. .
im not a mopar guy so I cant tell ya nothing about them.but I have a friend that's mopar crazy and can tell ya everything about them and I mean everything even down to what size bolt fits every hole in the damn engine and ill tell ya what he told me.318 not the poly were all dogs as far as mopar engines go.hes built 225 6s that would kill a 318.that was played with.but if you want to spend big bucks and do some traveling after used parts you can make them run hard and strong. but why? 340s and 360s were a better engine.according to him.he said that 318s were kinda like the flathead,they had their day.now it cost more to make them run than the hp you get .
Let's not forget the '70 340 Six Pak engines, eh? One of the harder running Mopars I've had was a ratty '72 Cuda. It was thrashed and abused when I bought it, and had a bone stock 340 hooked to a 3 speed manual tranny. This was the first year of the low compression 340. You had to rev it up a bit before you took off, because the TQ had very little accelerator pump left, but once you got it going it just ran hard, like it wanted to give you every last HP it had and then some.
The 318 was no different than many other engines out there - good strong dependable and able to pack a punch when needed. Yes it had bigger brothers however if a 318 was on offer and it fitted the frame then it is a good choice. The 318 was better than the 273 and yes 360 are bigger again however for good basic design and reliability they are hard to go past. Plus they used a good basic internal balancing approach where as a 360 was externally balanced and I've seen may a person curse a 360 when they got a mismatch of parts. Its all horses for courses - I have one in a OT73 Dodge pickup and its just the bees knees - the geabox is a NP435 and thats the limiting factor (wide gear ratio's) not the lack of grunt from the engine. Ma Mopar would not of produced as many as she did if there was a flaw in the design.
I personally really like the 318. I drove a '64 Dodge wagon in high school with a 318 with three on the tree. It wasn't as fast as the Novas, mustangs, or Firebirds, but with the stick and skinny tires I could burn rubber and the car was impossible to kill...I tried, a lot. Then I had an '84 Dodge van with the "new" 318. It was a slug of the biggest proportions, very forgettable, but it was nicknamed Old Reliable. Then I got a '92 Dodge van, full size conversion, with the 5.2L (318) Magnum. That motor would have made a killer engine in a rod. I would spank a guy that took the same route to work as I did that drove a Blazer with a 350 4 bbl. I actually had to show him the window sticker from the van to convince him it didn't have a 360 in it. It also ran with two kids in their 5.0 Fox body up to about 75 where I backed off due to traffic....that one had my laughing for along time, the look on the passengers face as I stayed right beside him as his buddy pounded gears was priceless. I think the 318 is actually way overlooked as a performance engine, there was a cop that lived behind me that scared the shit outta me with his built 318 in a '68 Cuda. Sideways all threw second gear......
I've had many 318's. Very good, dependable engines. The only one I ever raced was bone stock 2bbl in a '71 Duster with a 3 spd on the floor, it took a pretty good working machine to beat it, one guy was pretty upset that his stock '73 350 Nova couldn't beat it. A good buddy had a '68 318 2 bbl Polara that was plenty strong too, he would regularly outrun a '67 383 Monaco. This was all done late at night on a long straight stretch of the Trans Canada Highway.
Look at it this way. If you owned a car with a V8 that was a dog, and someone told you it would haul ass if you bored it .090 over, you'd tell them they were nuts. But a 318 is a 340 bored .090 under. The rest - cam, carb, heads etc. is interchangeable.
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