318 or 340?

[RustyRatRod]

I am not a fan of the magnum engine, of its Chevy rocker system.

How does that compare to Chevy?

Chevys had stud mounted rockers that were adjustable. The Magnums bolt down. Of the two, I would have to say that the Magnum is much more stable in that it is bolted rigidly, while the Chevy stud can and does flex. The two are just not comparable, IMO.

 

[318willrun]

P.S. - I did a personal test, and in my test I took the J heads, intake, carb and cam from a 340 and installed them on a 360. The 360 ran exactly 3 tenths faster.... this test was better than dyno proven, it was track proven... in the same car, same headers, converter, tranny, gears...

 

[RustyRatRod]

P.S. - I did a personal test, and in my test I took the J heads, intake, carb and cam from a 340 and installed them on a 360. The 360 ran exactly 3 tenths faster.... this test was better than dyno proven, it was track proven... in the same car, same headers, converter, tranny, gears...

lol

 

[273]

P.S. - I did a personal test, and in my test I took the J heads, intake, carb and cam from a 340 and installed them on a 360. The 360 ran exactly 3 tenths faster.... this test was better than dyno proven, it was track proven... in the same car, same headers, converter, tranny, gears...

Not exactly an apples to apples comparison cause of the converter and gears so it makes it an apples to oranges

 

[Bodyperson]

Not exactly an apples to apples comparison cause of the converter and gears so it makes it an apples to oranges

As close to apples and apples as you can get.

 

[273]

As close to apples and apples as you can get.

Not if you gear and stall each engine correctly
Smaller engines need more gear and stall of course the 360 should come out on top with the same gear

 

['73red-duster]

Small block in my opinion. 318, 360, or either magnum. Big block is great, but much more involved. What was the original engine? 8=easy. 6, you're going to have some changes. Tranny and k member

 

[justinp61]

To the OP build what's in your budget for the initial buy in, after that it's a wash. If I were buying unless I knew of a smoking deal on a 340 I'd go straight for a 360. The only way I'd consider a 318 would be if NOTHING else was available.

I always smile when guys bring up the small bore and larger main journals. There have been millions of 360 that never had any main bearing issues and many thousands 360 based strokers that are ran hard with out any problems. More internet conjecture IMO.

Cubic inches are king, especially in a cruiser.

 

[mopar jimmie]

Another choice is a 318 stroker , you end up with a 390 and get all the torque and HP that you could possibly use . I built one of these and they really give you alotta bang for the buck

 

[BlueDream]

A 360 is the better choice because you get more bang for your buck, but out of a 340 and a 318 I'd pick the 340 every time.

 

[stroked340]

If your just going to be farting around on the street then the "lame" 318 will be just fine.. if your want to make some real power get a 340 or 360..

 

[ir3333]

when you pull in to cruise night the first thing you'll be asked is if it has a 340
pay a little extra for the correct engine..you won't be sorry!

 

[Jplush]

I figured I would open up quite the discussion. The car was originally a 318 car so no worry about the 6 changeover. I appreciate all of the advice but I really do not want to get involved in a big block. While part of me really want's to be a purist and go with the 318, I feel that I am really more and more towards the 360 after reading through. No replacement for displacement, right?

 

[MrJLR]

If your just going to be farting around on the street then the "lame" 318 will be just fine.. if your want to make some real power get a 340 or 360..

Yes....because a "lame" 318 doesn't make "real" power.
318's make fake power...your car probably won't even move....

LAME statement....IMO.


:wack:

 

[justinp61]

when you pull in to cruise night the first thing you'll be asked is if it has a 340
pay a little extra for the correct engine..you won't be sorry!

Using that reasoning the OP should go straight to a Hemi.

 

[nm9stheham]

when you pull in to cruise night the first thing you'll be asked is if it has a 340
pay a little extra for the correct engine..you won't be sorry!

My son and I decided on 340 for one simple reason: resale value. Yeah, for street use a 360 would be just as good or better, BUT, those 3 numbers 3, 4, and 0, in that order, make people slobber.

Shopping for a 340 block is the key to pricing one down IMHO. We found an almost new one at the bottom end of the normal price range but it took some time, patience, and calling around. There is alot of trashy stuff out there to avoid. It was assembled with a 273 crank and lighter rods/pistons than the 273 had. So it was not much cost in the build beyond the $300 block that we would not have spent on a 360.

The one disadvantage is in finding good pistons for the 340. I have yet to run across a cheap set, i.e., less than around $350 or $400. You can find some good 360 pistons sets in the $150-ish range.

For the OP, if you are just plain leisurely cruising, the 318 is fine as well as any thing else mentioned. There IS some work that you need to do with 318 pistons or block milling that adds cost to make the compression ratio decent for perky street response. That makes the 360 easier. I personally would tend to shy away from big blocks in an A body due to the weight up front; the handling will adversely be effected. A stoked SB would be better in that department IMHO.

 

[70aarcuda]

put a 360 in it...and put a 340 air cleaner on it....99.9999999999% will never know the difference looking at it....

 

[Dartnut]

Whatever route you go, the key is having good machining, balancing, and assembly techniques as well as proper parts selection for your intended use.
That's where the real power is made.
I would seriously consider contacting a professional engine builder and see what they have to say about a combination for you and your REAL intended use for now and the future.
You might be surprised at what they recommend.........

 

[318willrun]

If your just going to be farting around on the street then the "lame" 318 will be just fine.. if your want to make some real power get a 340 or 360..

Here is a well built 318 taking on a turbo - charged Fox body ('stang). 318 in the far lane giving it a spanking.... lol.... (guy from Wis. that takes people's $$$$; sometimes ignorance cost)

[ame]https://youtu.be/hp1rvhJNa1I[/ame]

 

[Bodyperson]

Not if you gear and stall each engine correctly
Smaller engines need more gear and stall of course the 360 should come out on top with the same gear

I would think changing the torque converter and or gears would be less "apples to apples" than what 318willrun's test is.
I understand where your coming from but (no offense 318willrun) but how do we know his set-up is optimized for the 340 in the first place.
It would be fun to do that test on a dyno with optimally prepped blocks but then again it cant ever really be apples to apples cause theoretically they should use different cams and one could be built for torque... bla bla bla.
I thought it was an interesting test and really .3 is nothing to sneeze at in the drag racing world. So ya, in this case the 360is better.

 

[318willrun]

Bodyperson - for the record, 3.91 gears w/28 inch tires, 11 inch break-away TCI (about 2400 stall), 3200 pound car without me in it, cam was 280 advertised/.474 lift, Thermoquad on a cast intake, both engines at around 9.2 compression (replaced the dished 360 pistons with cheap 130 dollar pistons to get the 360 compression comparable.

 

[laj340]

You have a 318 block.stroke it...:finga:LAE419

 

[318willrun]

Oh yeah, the 318 in the video is stock stroke.....

 

[318willrun]

lol

lol.......

 

[JBurch]

Welcome to the world of MOPAR!

To the OP, as you can see, opinions like a$$holes every one has one, and I'll include myself in there. Little did you know what kind of s**t storm you would create when you asked the question: 318 or 340? In Chevy speak: what would rather have a 327 out of a Vette or out of a station wagon?

318, 340, 360 will all get the job done rather nicely, just a matter of affordability and availability. 318's (5.2's), 360's (5.9's) are common and affordable to the point of free if you look; 340's, not so much. The likely hood of finding an affordable 340 will more than likely be a result of luck than anything else. In your decision making process, the past commentary about bore size and main journal diameter is meaningless, it has no relevant anything to your stated goals for your car.

You made no mention of what your budget is. It is reasonable to think that what ever you find, it will need a rebuild. They will all cost about the same.

You stated the car is to be a cruser, I take that as you go out in the morning, hop into the car, start it up, back out of the driveway and down the street with no fuss, no muss, no bother. You appreciate thumbs up/smiles from passers-by. You go to a shine-n-show and people come by and say "nice car", if they ask if it's a 340 and it's not just tell them what it is, they just said it's a nice car.

In my opinion, 318 (5.2) or 360 (5.9) is the way to go, your stated goal of cruising and "sounds good" can be had from eather.



Good luck and have fun!