340 vs. 360 build?

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Go with the 360 Magnum...Roller cam!!! A good set of pistons and a block set up for a roller, it won't get much better!
 
You can buy a 360 for a $100 to $200 and use off the shelf pistons. The 318 stroker will require custom pistons, plus a crank and rods.

It will be cheaper to buy the 360 and stoke that with off the shelf pistons.
 
"they were never really intended to be a high performance motor.."

Well, actually, the 360 was originally designed as a performance motor. That's why it has a much more beefy crankshaft and larger main bearings than a 318 or a 340. And, BTW, that Chrysler cast crank is bulletproof! Have you ever heard of anyone breaking one? I haven't.

Lemmee tell you how it was:

Chebby came out with the 283. Ma Mopar said, "We need MorePower than Chebby!" So they came out with the 318.

Then Chebby came out with the 327. Again, Ma Mopar said, "We need MorePower than Chebby!" So they came out with the 340.

And then Chebby introduced the 350. True to form, Ma Mopar said, "We need MorePower than Chebby!" And they designed the 360. And since they intended it to produce so much power, they increased the size of the crank and mains.

But then the smog laws kicked in, and they had to turn the 360 into a smog motor. But the only things that changed were the pistons and heads; nothing that any mechanic can't easily correct, and then you'll have the kind of 360 motor that the Chrysler engineering department originally intended you to have.
 
Bill Crowell said:
"they were never really intended to be a high performance motor.."

Well, actually, the 360 was originally designed as a performance motor. That's why it has a much more beefy crankshaft and larger main bearings than a 318 or a 340. And, BTW, that Chrysler cast crank is bulletproof! Have you ever heard of anyone breaking one? I haven't.

Lemmee tell you how it was:

Chebby came out with the 283. Ma Mopar said, "We need MorePower than Chebby!" So they came out with the 318.

Then Chebby came out with the 327. Again, Ma Mopar said, "We need MorePower than Chebby!" So they came out with the 340.

And then Chebby introduced the 350. True to form, Ma Mopar said, "We need MorePower than Chebby!" And they designed the 360. And since they intended it to produce so much power, they increased the size of the crank and mains.

But then the smog laws kicked in, and they had to turn the 360 into a smog motor. But the only things that changed were the pistons and heads; nothing that any mechanic can't easily correct, and then you'll have the kind of 360 motor that the Chrysler engineering department originally intended you to have.
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What....the 350 was out YEARS before the 360 was even a thought....and the 340 was designed to go after everyone elses small blocks,it was put in nothing but performance cars..360's were put in everything from trucks to taxi cabs..i would'nt call it a performance motor more like a utility motor..
 
340srule said:
What....the 350 was out YEARS before the 360 was even a thought....and the 340 was designed to go after everyone elses small blocks,it was put in nothing but performance cars..360's were put in everything from trucks to taxi cabs..i would'nt call it a performance motor more like a utility motor..
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That's right. There were only 2 motors during that era that was specifically designed for performance. One was the 426 Hemi and the other was the 340. Neither were available in trucks or 4 door passenger cars.

Can't say the same for GM or Ford. The 350, 351, 396, 427 (GM and Ford), 428, 429, 454, all synonymous to performance for GM and Ford, were truck or passenger car motors modified for performance.
 
"What....the 350 was out YEARS before the 360 was even a thought...."

340srule, you sound like you're trying to disagree with me, but I said the same thing you're saying...Mopar introduced the 360 partly in order to have a higher -performance engine than the Chevy 350. The 350 came out in late '67, and the 360 was introduced in late 1970 (for 1971 models). So the delay of 3 years invalidates what I was saying? I don't think so.

"...the 340 was designed to go after everyone elses small blocks,it was put in nothing but performance cars..360's were put in everything from trucks to taxi cabs..i would'nt call it a performance motor more like a utility motor.."

Again, you appear to be taking issue with what I said, but you're agreeing with me. Like I said, the 360 never became a performance motor, even though it was originally intended to be one.

Methinks thou dost protest too much.
 
I say go with a 318. I have a 318 in my 76 dart runs 12.95 @ 102 Mph, with a 1.78 60ft. My dad has a 360 in his 76 dart and runs a 12.91 @ 104Mph. We both have about the same into each others motor. Here's my combo:
318 30 over
kb399
360 heads milled .035 mildly ported 1.88/1.60
erson .488/.510 234/244
ed air gap
650 dp holley
904 trans 3500 stall
8 3/4 410 gears
weighs 3250
Here's my dads combo:
360 30over
kb190s
308 heads 1.88/1.60
crower .485/.495 222/234
ed air gap
750 3310 holley
904 trans 2600-3200 stall
8 3/4 391 gears
weighs 3350
His best 60 ft is 1.84.
318's ROCK.
Everyone told me not to build a 318 so it made me want even more and to show poeple that 318 can be a performance engine.
 
Switch carbs--than see what happens. Those vacuum secondarys are nice to drive on the street but you lose time waiting for them to open running the Q.
 
My dads got the quick change on the 3310 and messed with the springs and found the best one. It didn't like all that gas at first. Do you think he should try a different carb?
 
Fiinally I see a build that is VERY comparable to what I'm doing with the 318 in my Dart Sport and I see some specs of what she'll do when she gets fired up. BTW Way to go 76318Dart, I here so many people talk about 318s being "dog terds", "boat anchors", etc, but what most people I think never realize is that most of the cars we all buy to build came with either a 273, 318, or a /6. The options were there, and even though there were higher perfomance options, most of these engines came out pretty peppy themselves for what they were in their day. Most of these guys are talkin about makin their cars 10-sec or 11-sec cars but you are runnin 12's on a 318. Now if you were back in the era these cars came out in, you actually had something special. So, ROCK ON with your 318!!!
 
76318dart said:
My dads got the quick change on the 3310 and messed with the springs and found the best one. It didn't like all that gas at first. Do you think he should try a different carb?
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Even so, the vacuum carb secondarys do not open all the way until 5500 rpm-if they even open all the way.

Vacuum secondary carb are never used in racing motors for that reason.

You dad may not like the DP on the street but running the quarter mile is were it show up best. Sounds like its running good now, just was pointing out why your 318 might be as good.
 
360's were also designed to drag the ever heavier cars and trucks being built around, like the 400 Chevy smallblock, and needed torque more than rpm, thus the 3.58 stroke.
Then came the gas crisis/emissions Nazi's and no lead, and all the manufacturers dumped the compression and put all sorts of gizmo's on the engines to try and improve emissions...low compression and low emissions are contradictory to each other, makes it tuff to get a complete burn.....
Early 71-72 360's had a stock flat top piston and a little better compression ratio, as opposed to 73 and later dished pistons.
What's cool is....the early pre 75 360 used the same block coring as the 340 did, with a smaller bore....meaning some 360's can be bored .040...and then .030 more....which makes somewhere around 372 cubes....with stock parts. (Except the pistons). he he he
360= 4.00 bore X 3.58 stroke
340= 4.04 X 3.31
Usually easily overbored .030 to 4.07

The 360, bored .040=4.04....+another .030=4.07....same as a .030 over 340.
So a .040 360 with an early block, is the same as a standard bore 340.
Lots of meat left! And some 340's have been safely bored + .060....
And now, there are cranks for the 360 available with the 3.31 stroke...
So now you can have a 340, without having to pay some parts hoarder big bucks for a worn out original block, or coughing up $1500.00 or more for the MP "resto" 340 block.
Or buy a $300 dollar cast crank, some new pistons and have 408 cubes of spot weld destroying fun, with plenty of meat left for future rebuilds. Which is probably better anyway, since trying to find good used 71-74 360's ain't that easy anymore.
It's all front drive junk and trucks in the Mopar row at my junkyards....
But if you've got an early block laying around....... he he he:toothy10:
 
I have a bum right shoulder, can't work and have tons of time to read old posts, so i thought what the hell? I will probably respond to a few more old ones, if i think can contribute something worthwhile.Or at least entertaining!
Alan627b
 
71duster06 said:
If you want instant power with little mods then go 340...a good high compression one that is.....there already built from the factory but with the 360 route nearly everything will have to be replaced or upgraded. they were never really intended to be a high performance motor..though if you get your hands on a 360 police motor you have a great starting point
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This couldnt be further from reality IMO.I'll take a 7.8:1 360 in a street car vs a 9.2:340(that's what the real compression of a high compresion 340 is) in a second. Only thigns chagned are pistons and cam. Same as in a rebuilt 340. There is much more mystique around 340s, that's all. And a police 360 had a windage tray and different cam. That's it. I like the 340's bore sizze, but the later 340s are thicker in the right spots by my testing.
 
dodge freak said:
Even so, the vacuum carb secondarys do not open all the way until 5500 rpm-if they even open all the way.

Vacuum secondary carb are never used in racing motors for that reason.

You dad may not like the DP on the street but running the quarter mile is were it show up best. Sounds like its running good now, just was pointing out why your 318 might be as good.
Click to expand...

A well set up vacuum secondary carb only gives up .1-.2 seconds to a DP in the 1/4.

I guess you missed all the Max Wedge and Race Hemis with vacuum secondary carbs.
 
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