Where's the 340 crate engines???

[72_Durstya]

Why hasn't Mopar given us a 340 Crate Engine yet? It only makes sense to me that they would, given there were only like 4 or 5 years that it was in production for let alone the demand for them right now. I don't know about everyone else but I would much rather have the "semi hemi" 340 in my car then the 360. So Ma Mopar if and when are you gonna give us what we want?!

 

[rumblefish360]

Not going to happen. I'll tell ya why. Recasting the 340 block is one thing and they made it so. Did you see the price????????
Now add a asemble to that order and the more expensive internal balancing.

The current 360, dispite what you'll rant and rave on about the 340, is;

20 inchs larger
cheap
readliy avilable to use
Made much much cheaper.

Also, the 273-318-340-360 engines are not a "Semi HEMI" but the earlier 318-301-277 poly engines are called that. They have a canted valve design.
Theres no such thing stock as a 340 semi hemi.

 

[72_Durstya]

Well it would be nice if it would come true. and i was just refering to the 340 as a semi hemi becuse it was kinda like the hemi of small blocks as far as performance was concerned.

 

[AdamR]

I'll take the longer stroke of the 360 any day. Better yet just make it a 4" stroker.

 

[dgc333]

Well it would be nice if it would come true. and i was just refering to the 340 as a semi hemi becuse it was kinda like the hemi of small blocks as far as performance was concerned.

But a 360 built to equivalent specs will out run a 340 any day, it's got 20 more cubic inches. Even the 5.2L (318) magnum motor used in the trucks up until the 5.7 hemi makes more HP than the 340's did.

You have to remember that mopar engines up through 72 were rated on gross HP, that is, no alternator, no water pump, no exhaust, no air cleaner. After 72 the numbers were net which ment alternator, water pump, exhust, air cleanre, etc.

FWIW, mopar is selling what they call a 340 block but this block but this block is ment for serious big cube engines and can support over a 4.1" bore which allows them to sell a 440 small block.

 

[rumblefish360]

There also a resto block. Is that what your thinking dgc? It seems to be the old race block with resto numbers on the side or something like that.
To much money for that crap.

 

[whitey]

I do beleive that Mopar has NOW issued a 340 six-pac (stroked out) crate engine. I can't remember what magazinge I saw it in but when I saw it I showed it to my brother.

 

[bac2nowere]

But a 360 built to equivalent specs will out run a 340 any day, it's got 20 more cubic inches

When I used to run dirt track cars you could tell a big difference between a 340 & a 360. the 360 had a lot more torgue and pulled hard out of the corner, but flattened out pretty quick. 360 also wouldn't live as long.

340 would come to life just exiting the corner but it would not stop until you backed off the gas.
Bye the way, all parts where stock except the purple shaft came we ran, Even the vavle springs where stock,if I remember right I think it was the valve springs the pink stipe or something like that. And the 340 would twist about 8 grand with out no probs.

 

[340mopar]

But a 360 built to equivalent specs will out run a 340 any day, it's got 20 more cubic inches. Even the 5.2L (318) magnum motor used in the trucks up until the 5.7 hemi makes more HP than the 340's did.

You have to remember that mopar engines up through 72 were rated on gross HP, that is, no alternator, no water pump, no exhaust, no air cleaner. After 72 the numbers were net which ment alternator, water pump, exhust, air cleanre, etc.

FWIW, mopar is selling what they call a 340 block but this block but this block is ment for serious big cube engines and can support over a 4.1" bore which allows them to sell a 440 small block.

NOT

 

[dgc333]

When I used to run dirt track cars you could tell a big difference between a 340 & a 360. the 360 had a lot more torgue and pulled hard out of the corner, but flattened out pretty quick. 360 also wouldn't live as long.

340 would come to life just exiting the corner but it would not stop until you backed off the gas.
Bye the way, all parts where stock except the purple shaft came we ran, Even the vavle springs where stock,if I remember right I think it was the valve springs the pink stipe or something like that. And the 340 would twist about 8 grand with out no probs.

You are not talking about equivalently built engines if all parts but the cam were stock. When the 360 arrived it was relatively low compression engine with smaller valves than a 340.

 

[dgc333]

NOT

NOT what?

That an equivalently built 360 will out run a 340?

Or, that a 5.2L magnum makes more HP than a 340?

Lets see you build a 360 and a 340 both with the same compression, same heads, same valves, same cam, same intake and same carb. Now the difference is 20 cubic inches of displacement. The 340 will rev higher because of the shorter stroke but the 360 will make more power every where else because of the additional cubes. Like they same there is no replacement for displacement.

The 340 six-pac was rated at 295HP and the 4bbl was rated at 275HP. These were gross numbers. The net rating is generally accepted to be about 25% less than the gross rating. That makes the 340 six-pac rated at 221HP and the 340 4bbl rated at 206 both below the 235HP net number of a 5.2L magnum.

 

[bac2nowere]

You are not talking about equivalently built engines if all parts but the cam were stock. When the 360 arrived it was relatively low compression engine with smaller valves than a 340.

Guess I should have made my self a little more clear. All components where stock except the camshafts. All the heads we ran where J heads port & polished. 202 & 188 valves. There may have been a little difference in compression. However, the point I was trying to make the there is obvious a difference between the 360 & 340. The 360 works better at lower rpms & the 340 with a bigger bore & shorter stroke will turn more rpms & and runs better at higher rpms than the 360.

 

[dgc333]

Not disputing the rpm capabilities of the 340 but the 360 is no slouch in it's ability to turn rpm's either. Also, if your dirt track cars were using stock bottom ends the compression difference was on the order of two full points, approx. 10.5 on the 340 and less than 8.5 on the 360. And you mentioned 2.02 and 1.88 valves, 360's came with the 1.88 intake valves which will limit the top end power compared to a 340 with 2.02's.

I still contend that if you build two identical engines except for the small bore difference and the stroke difference the 360 will get you down the track, around the oval or through the road cross faster because it's going to make more power over a broader rpm range because of the additional displacement.

 

[rumblefish360]

I see what he's saying though. The shorter stroke reved up quicker and probably, IMO I would do a taller (Numericaly higher) gearratio to exploite the engine and how it reacts differently to a longer stroke engine. Even if all other parts are exactly the same.
I've also notice pro teams have sevreal engines built for different tracks. All in a cube limit.

 

[SwingerMan]

I do beleive that Mopar has NOW issued a 340 six-pac (stroked out) crate engine. I can't remember what magazinge I saw it in but when I saw it I showed it to my brother.

You saw correct Mopar is coming out with three different 340 based crate engines one of which is the six pack your talking about. THe one that has my interests peeked is the 440 CI stroker based of the new 340 block that is utilizing the new "Commando" heads (supposedly a cross between the W2's and the magnum heads. Supposed to be a 500+ horse motor :headbang: , they have part numbers but they have not been release for sale yet. I will have to dig up that issue and post the details.

 

[Guitar Jones]

Just something to chew on, and this is from experience.

My 340 pulled really really strong on the top end, I used 5.13 gears and shifted at 8000.

The same exact motor but without the good Ross pistons and Eagle H beam rods in a 360 leaves harder but doesn't run as strong on the top end. I use a 4.89 gear and shift it at 7500.

They both ran the same ET within .01 of each other.

Having said that I'll tell you this, anything over 8000 RPM's shook the valve lash adjuster lock nuts loose. The valvetrain geometry is bad (we all know this) on the 59* blocks so trying to continually rev one much higher than 8000 will get you a bunch of pieces parts.

 

[Guitar Jones]

Oh and one more interesting note I forgot to add because I'm old, the 5.7 hemi has a 3.91 bore size. Sound familiar? It should, it's the same as the 318. It also has a stroke of 3.58. Hmm, that also sounds familiar. Just happens to be the same as the 360LA.

Hmm, things that make you say, WTF over?

 

[khughesprime]

Bottom line. The 340 was UNDER RATED and had much better compression than a 360. These are 2 entirely different engines. If you had like components and built up a 340 block and a 360 with the same bores- The 340 is always better. The 340 is the "hemi" of the Mopar small blocks. No hemispherical combustion chambers -BUT it is THE small block of Mopar. New 340 crates? AWESOME :headbang:

 

[fishy68]

This has turned into one of those "Can of worms" debates that really never ends. You can't compare stock 340's to stock 360's just like you can't compare apples to oranges. There's just to many differences. Compression, valve size, cam size, carbs, exhaust manifolds, etc.... The shorter stroke of the 340 naturally revs higher but produces less torque than the longer arm 360. The longer stroke 360 produces more low end torque, period!! The larger 360 mains have a little more friction that take away a little power so that's a deficit to the 360.

For a street/strip car give me the torque anyday. I like to iniliate tires.

 

[Riley Craig]

Hi, my name is Riley and im really new to all this... but i seen this post and i was really hoping that there are people still following this thread. My father-in-law died this past year and my wife and I finally started to clean out his house. When we started in the garage i noticed his Plymouth Duster he built. Well when we went to pull it out i noticed a what i thought was just a bunch of plastic in the corner but to my suprise there was a motor that appears to be new. He had purchased it online and had it shipped to the house. Im not sure if it was crated or rebuilt? But its just a case with heads on it. When i read the stamp i had never noticed the numbers. It appeared to be a 340???? I just need some help trying to figure out what exactly it is and what its worth? All i know is its bolted to a board thats on wheels still and just sitting in the corner... its got light rust on the case but the heads and valves appear to still be lightly oiled and rust free still? I added a pic of the numbers if anyone can please help me figure it out! Im completely lost to what i have here

 

[Brooks James]

Bottom line. The 340 was UNDER RATED and had much better compression than a 360. These are 2 entirely different engines. If you had like components and built up a 340 block and a 360 with the same bores- The 340 is always better. The 340 is the "hemi" of the Mopar small blocks. No hemispherical combustion chambers -BUT it is THE small block of Mopar. New 340 crates? AWESOME :headbang:

Someone here said that the 68-71 340
Made 320 hp, as told to him by a mopar engineer, however I also saw an article where a completely stock one had just over 300hp. I more inclined to believe 320 as the small block 350 Chevy rated at 300 hp didn’t have the compression, big valves, or better camshaft, intake that the 340 had.
A stock 360 magnum with a good intake, headers and good carb has been dialing in at 310-320 hp with a tiny cam and valve springs that are all done at 5000

 

[fishmens67]

Someone here said that the 68-71 340
Made 320 hp, as told to him by a mopar engineer, however I also saw an article where a completely stock one had just over 300hp. I more inclined to believe 320 as the small block 350 Chevy rated at 300 hp didn’t have the compression, big valves, or better camshaft, intake that the 340 had.
A stock 360 magnum with a good intake, headers and good carb has been dialing in at 310-320 hp with a tiny cam and valve springs that are all done at 5000

It depends on which 350 Chevy you're talking about.
the 1970 Z28 LT1 350 was rated 360 HP with 11.1 comp and a solid cam.
they had a nastier idle than the 340 had.
Chevy produced a few performance levels of the 350.

 

[gzig5]

Hi, my name is Riley and im really new to all this... but i seen this post and i was really hoping that there are people still following this thread. My father-in-law died this past year and my wife and I finally started to clean out his house. When we started in the garage i noticed his Plymouth Duster he built. Well when we went to pull it out i noticed a what i thought was just a bunch of plastic in the corner but to my suprise there was a motor that appears to be new. He had purchased it online and had it shipped to the house. Im not sure if it was crated or rebuilt? But its just a case with heads on it. When i read the stamp i had never noticed the numbers. It appeared to be a 340???? I just need some help trying to figure out what exactly it is and what its worth? All i know is its bolted to a board thats on wheels still and just sitting in the corner... its got light rust on the case but the heads and valves appear to still be lightly oiled and rust free still? I added a pic of the numbers if anyone can please help me figure it out! Im completely lost to what i have here

View attachment 1715745434

Going to need a lot more pics of the engine if you expect a decent answer. Could be anywhere from $100-$5000 or more, depending on what's there.

 

[66fyssh]

Hi, my name is Riley and im really new to all this... but i seen this post and i was really hoping that there are people still following this thread. My father-in-law died this past year and my wife and I finally started to clean out his house. When we started in the garage i noticed his Plymouth Duster he built. Well when we went to pull it out i noticed a what i thought was just a bunch of plastic in the corner but to my suprise there was a motor that appears to be new. He had purchased it online and had it shipped to the house. Im not sure if it was crated or rebuilt? But its just a case with heads on it. When i read the stamp i had never noticed the numbers. It appeared to be a 340???? I just need some help trying to figure out what exactly it is and what its worth? All i know is its bolted to a board thats on wheels still and just sitting in the corner... its got light rust on the case but the heads and valves appear to still be lightly oiled and rust free still? I added a pic of the numbers if anyone can please help me figure it out! Im completely lost to what i have here

View attachment 1715745434

Sure looks like a 340 to me. Check out this How-to from @krazykuda .

How to ID a Small Block Engine Block:

 

[diymirage]

@Riley Craig
this is a numbers game

the first thing you want to do is see if you can locate the VIN pad and post those numbers here
that will tell us what vehicle it came with, or if it was a "crate engine"

(if it came with a vehicle, often times the owner will be glad to be reunited with it)

the look at the heads and post the casting numbers

what is all included in the block?
is it just the block, with or without caps
does it have a crank?
pistons?

and do you have a way to measure the bore?


toss some more pictures up too, that always helps