340 Vs 360

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bighammer

bighammer

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I was talking to an older gentleman that I've known for years about LA blocks. He is very familiar with Mopar, as he is a retired mechanic and owned many Mopars.

I told him of my plans to do the 318 / 360 swap. He suggested a 340. That surprised me. I am not sure if he is as familiar with the 360, as he has been retired many years.

But this got me curious, what is the basic difference(s) between the two? I know that for the guys restoring a car, an original engine is the way to go, but what about nothing other than a performance upgrade?
 
The 340 has a slightly larger cylinder bore. If i remember correctly. that allows for a few more Cubes when boring or stroking. I am sure others will add to this but that is what sticks in my mind right now.
Rodney
 
360 has a 4.00 bore std, 340 is 4.040 std. 360 has a 3.58 stroke, 340 is 3.31. The 360 is also a cast crank engine, 340 can be steel, or cast. 360 main bearings are larger. Motor mounts are interchangeable. Oil pan is not, it is 360 specific. For a mild street engine, either one is capable of great performance. The 340 will allways have the reputation though, and usally more resale value..
 
If you can find one that won't cost an arm and a leg, go for it. Having a 340 would be really cool but you can really pay a premium since they're rare and valuable. In terms of performance, though, a 360 will do just about anything the 340 can. The bores are about the same 4.00" (360) vs 4.04" (340) but the added stroke of the 360 (3.58") will help a little with low-end torque.
 
There is no "versus" here. Both are a great option! If you don't have a motor, there is no need to go 340 simply because they are usually much higher priced. The 360 is very easy to get in great running condition, and offers loads of performance. The cam, heads, intake and rods all interchange with 318, 340 and 360. Also, if your just going to do the "mild head and cam" upgrade, my money would be on the 360 anyways, as I've built both. But should you happen to come by a cheap 340 in good shape, by all means jump on it. The real story here is you can't make a bad choice.
 
The 340 was Chrysler's "performance" small block from factory, giving it a reputation among some to be superior to the larger 360.

But IMO this is a misconception. Unless you are doing a restoration on an original 340 car I would recommend the 360.

The blocks are different

360 bore = 4.00"
340 bore = 4.04

The crankshafts feature a different stroke and main journal diameter, the stroke difference makes up the bulk of the difference in displacement.

This means a factory 360 crankshaft cannot be used in a 340 block. (not without substantial modification, anyhow)

360 Main journal diameter = 2.810"
273/318/340 main journal diameter = 2.500"

360 stroke = 3.580"
273/318/340 stroke = 3.310"

Both the 340 and 360 engines used cylinder heads with larger ports and valves than 273/318 heads.

For performance, the larger displacement of the 360 provides a clear torque advantage over the 340. Furthermore, the 340 engine is often more expensive due to limited production numbers and a result of it's performance oriented marketing history.
 
I agree with the above post. The 340 was always a performance engine. It has a reputation of being a strong performer. The 360 mostly came with 2-barrel carburation and came about in the smog era.

The 360 already has 20 cubes on the 340 and when built the same, it will perform better. Build a 360 and put 340 stickers on the car if you want to.
 
The old school thinking was that a larger bore and shorter stroke engine would get into its power band quicker than a smaller bore/larger stroke engine.
 
Oh brother. Another 340/360 thread. Do a search and you should see quite a few threads on this subject.


Back before you could get cheap off the shelf pistons for a 360 the 340 ruled. These days the 360 is the way to go. If you find a cheap 340 flip it to a resto guy for a nice profit and use the money for a 360 build.
 
Hey Abodyjoe..not meaning to divert from thread topic but what size pistons is that girl holding in your avatar...can we get a closeup maybe so we can see the numbers,overbore etc...jus wonderin
 
Nobody mentioned floating piston pins or windage tray. For stock vs. stock, the earlier hi compression 340 has it. For building a motor, I paid $150 for a running 360 core. 360's can be built very strong, all the motor you want in a street car.
 
Main difference for most of us:

360 is a couple hundred bucks, perhaps even running and driving, and maybe with a trans.
Probably a dozen on your local craigslist.

340 is about 500 bucks minimum, and usually condition and completeness is questionable.
Might be lucky to find one at a swap meet or on this board.
 
Thanks guys for the rapid, informative responses. I know this topic has been discussed many times, but I wanted to get a little clearer picture of the differences so that I could convey this info to my retired mechanic friend.

And, by the way, I already have my replacement 360 Injun on a stand getting ready to do the swap! Based on info I learned here on the site!

FABO rocks because of members like you (you know who you are)!
 
The 360 heads came with 1.88" intake valves, You can have a machinist open them up to 2.02" intake valves for the 360 and they will run better.

The 340 had forged crank from 68 - 72.
73 is the only year for the cast crank 360.

All 360's had cast cranks.

340's had forged rods and cast pistons.
340's had 10.5:1 compression from 68-71

360's were typically around 8:1 compression.


Take a 360, and bump the compression to 9.0 - 9.5 and put 2.02" intake valves on it and let her rip. It will run as good as a 340 for less money. 360's run great when you use the "hi-po" 340 parts in them.
 
you would build each a little different.
the 360 has a bit more torque,the 340 is a quicker revving motor
if you find one of each for sale at the same price,the 340 will disappear quicker.
if you lived through the late sixties,i know which you probably prefer.
 
Throw them in the ditch. They both suck.
 
IMO, the 360 is a better street and street trip engine. The added stroke hands back a nicer torque curve that you'll want in a heavier street used car.

Now when it comes to the "Strip only" it is tasters choice.
And often you'll find a stroked engine throwing the debate out the window.
 
Stock
340 rev quick, and have a short life.
360 rev slow and last several 100,000 miles.
I will take a 340 for a street car any time, but there is something to say about my dads stock 78 power wagon, 360 with 244,000 miles with nothing but a timing chain, valve job and gaskets to keep it going, short block is stock 1978.
 
I don't know where in 'ell people get this "rev fast," "rev slow" nonsense. An engine only revs UNDER LOAD as fast as the HP/ torque output and the gearing allow.

The fact is that the longer the stroke, the faster the pistons move, so if you want to talk about "last a long time" in theory the pistons, rings and cylinder walls on a short stroke engine should last LONGER when operated at the same RPM

There's a lot more to engine design than the length of the crank arm
 
360 will always have a lighter rotating assembly then a 340 ......since the 340 has a 1.84 compression height vs the 1.67 for the 360, the 360 will have lighter pistons......hence the 360 will balance with a light bobweight...

so the 340 defies the law of physics,,.LOL......
 
History sets in, the problem is that short stroke motors do not last longer than long stroke motors.

If so a slant 6 should not last more than 50K miles with the stoke it has.
 
sireland67 said:
History sets in, the problem is that short stroke motors do not last longer than long stroke motors.

If so a slant 6 should not last more than 50K miles with the stoke it has.
Click to expand...
I dunno son, sounds like your posting some BS with these comments.......
 
Think of the 360 as a stroked 340. Or the 340 as a over bored 318 which is an over bored 273. Each is just a progression of the original design and an improvement IMO. Had they built a 360 in the true muscle car years as a muscle car motor the advantage would have been clear. You see a lot of Chevy guys making the same claims on the 327 vs the 350.
 
340 vs 360 on a full out race engine build both taking out to there max rpms the 340 would have a advantage over 360 with its bigger bore (better breathing) and shorter stoke (higher rpm capability).

340 powerband will be 300-500 rpms higher than a similar 360 which would make the 340 needed more stall and gear to give same performance as a 360. And yes a similar prepared 360 will make more torque then a 340 but that only matters if your racing dyno numbers with the right gearing both will put similar torque numbers to the ground. The main advantages a 360 has lower cost power will be lower in the powerband and requiring less gear and stall, all around just a little more streetable. Or use 340 block with a 3.58 crank and have best of both worlds.
 
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