What is so great about a 340 HP engine ?

[skip68]

Just wanted to know what was so great about the 340 engines. And, is a 360 a good motor?    Thanks,              Chuck................

[Rolling_Thunder]

ummmm    high horse power potential and can Rev like no other...          360 is a good motor - more torque generally - but doesnt rev as high

[Ghoste]

Chrysler designed the 340 to be a performance engine from day one.  There were no low performance versions built.  No two barrel 340's, no truck 340's, no entry level 340's.  Right from day one, it was intended to be a high performance engine available only in high performance cars sold with the other needed high performance drivetrain options.  The only other Mopar engine you can say that about would be the 426 Street Hemi.

[skip68]

Thanks,  I wanted to know because I found a RR that might have one in it.   Chuck..............

[Ghoste]

I should qualify that statement slightly by pointing out that it was detuned slightly in 1972 to meet emission standards.  Compression was dropped slightly and i think the heads were changed?  So, in that context you could say a "lower" performance model was offered, but, all else being equal...

[bull]

I'd take a 340 over a 360.

[Troy]

I've been reading up a LOT on this topic and here are my observations:
If you want to build one from scratch and have nothing then go with a 360. The cores are cheaper to find, you get an extra 20 cubes, and most parts are interchangeable. Be sure you know whether it's internally or externally balanced though (318s and 340s are always internal).
If you have a 340 then build it - unless you think it may be the numbers matching motor for some other Mopar guy. It's getting harder to find good 340s and the supply is already limited since they were only produced for a few years vs ~30 years for the 360. From what I understand they are powerful motors but may have some weak spots (cylinder walls?). I'm sure most "average" guys can't kill one.
If you have a 360 then build it. Parts are plentiful and relatively cheap. I high winding small block is pretty cool.
If you plan on racing then build the 360 since you won't need to try too hard to replace it if/when you blow it up and you'll find a bit more torque.
If you want to race and/or have a large/unlimited budget then get one of the new 340 crate blocks. You get the benefits of the 340 (strength, race heritage, etc.) in a brand new package that's been modified to make it even better.

I'd really only consider a 340 in my cars if I got a great deal on one. Otherwise I will leave them for someone who needs a 340 for "correctness". I can definitively say that because I just passed on a 340 for a 360 Magnum...

Troy

[skip68]

Thanks Troy and bull, that makes sense.   I'll find out tomarrow what it's got.        Chuck.............

[whitehatspecial]

Since I can remember I wanted a 340 in a street car. I remember having the run of my life against a 340 Demon back in the 70's when I had my built '68 396 SS Chevelle.
That little Demon pulled me until I reached 3rd gear and even then it was very close.
Long story short, I now have a built 340 in my '68 Charger and it is all I remember it to be. Found the original bore block with J heads, rods, and crank for 500.00. I probably have another 4k into it with machine work, valves, and other goodies. It also sounds great with Magnaflows.
BTW the original 318 is under my bench on a dolly should the original motor question ever arise.

[max]

(318s and 340s are always internal).
Troy

actually some stock 1972 and all stock 1973 340's used cast cranks and they were externally balanced so be careful of that one. here is a photo of a stock cast crank damper and casted into the damper are the words "use with cast crank 340's only" starting at the 12:00 o'clock position in the photo you can barely see it.

a few years back i built a .040 over 360 with a set of "O" heads and a stock 340 cam advanced 5 degrees a performer intake and a 750 cfm holley and it was installed in a 1967 dart.

the 360 engine had a bearing failure and had to come out so i had a .030 340 short block sitting in the garage and i took the cam, heads, intake and carb off of the 360 and bolted it on the 340 and set the cam up just like i did in the 360 and put it back in that 1967 dart.

the engines were as different as night and day. the 360 had better bottom end but nosed over in the higher rpm range but the 340 was slow off at idle but came on strong in the mid to upper rpm range.
now there were some difference in the cubes between them so that needs to be factored in but the 340 had alot better top end power to it even with the stock 340 cam.     

[GTX]

Years ago when I was running a really well built 440 in a '73 Charger I came up on a purple '73 and we were having fun going at it. At first we were only doing short bursts and I was getting by him each time. We kept pressing it and soon we were going all out. Each time I was barely getting past him. I'd get the jump on him and then he would come up on me.
We pulled over and chatted for a bit, he said that he wanted to run me because he heard that I was running a hemi. That was a rumor started by one of the guys at the local Super Shops store.  I laughed and told him that no, I had a 440 and asked what he had. He opened his hood and showed me a 340!!
That thing was quick, I don't know the gearing on it and I forget the engine spec info he gave as it was about 20 years ago but the bottom line was that a well built 340 has the potential to really run hard. These were the identical year and model cars and neither of us had anything spectacular done except for lot's of engine and trans work. I did grant him that he had probably a bit more hard core tweaks than me though like his heads were better than mine.
I never lost a race to anyone in that car but he came close.
Now on the other hand, except for maybe the Magnum 360 I'd walk away and go for a 340 it the choice is 360 or 340. I put a 360 in my Ramcharger when the 318 got old only because there wasn't a 340 to be found and that thing was dog.

Just my .02 but I'm no pro.

[Bandit72]

i put a 360 in my 62 D-100 and even with a horrible carb. that thing will scream!

[XXSpiralXX]

doesn't Mopar now offer a replacement Race block for the 340? If I remember it wasn't that expensive.

[bordin34]

Yup right here $2289
edit-working link
http://www.mopar.com/m_perf_subcat2Check.jsp?SubSubSubGrpID=222&dummy5=1172015836517

[XXSpiralXX]

Damn!    I didn't think it was that expensive. I thought the bare block was like 800 bucks. .....

[max]

Damn!    I didn't think it was that expensive. I thought the bare block was like 800 bucks. .....

a couple of years back when i orderd my new 426 hemi block the dealer told me then that the 340 block was more expensive then the hemi block for some reason.

[evil1]

Back in high school i had a 71 340 Demon 4sp., man that thing was quick. Had a friend who had a 69 chevelle ,he was always telling me he wouldn't trade 1 (chevy) 350 for all the 340s ever made, so i beat that chevelle bad enough , he bought a 340 cuda a couple months later.

[Steve P.]

Damn!    I didn't think it was that expensive. I thought the bare block was like 800 bucks. .....

If that block was only 800 smacks they would never sell another motor....