In need of an education..340 vs 360.

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71dusterdan

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Hey guys, I've been a 360 man since I had my 1st one built back in high school. I have spent the last 20 plus years absorbing everything I can about hot rodding 360's. I had settled on a .30 over flattopped, eq headed, magnum rockered, performer intake and Tq carb. The cam was still up in the air, but i am only looking for max rpm of 6k, daily driver capable, with decent economy in front of my 833od . Well then a low mileage, under 50k, clean stock 340 fell into my lap. a virgin 71. I know NOTHING about 340's. Other than I rode in a 73 340 4 spd Duster as a teen, and it was the most impressionable car I'd ever ridden in. I've been in faster, quicker winding, louder... but something about that combo kicked me in the butt and I was a believer ever since. So what I do know for sure...it has a small damper and is drilled for a pilot bearing...leading me to believe it is a forged crank. It has my favorite carb....a TQ. our best guess is this thing being a 71. What can I look for and where to check the year? What can I check with the heads still on the block to tell me if the heads are a desireable casting...ie 2.02 valves. Compression? Now based on my wants and the 360 parts I have, will they do anything beneficial to a 340, would the eq heads be an improvement? or should I just toss in a decent cam, rings bearings and gaskets and go have fun? Thanks...any and all input regarding the 340 will be much appreciated.:violent1::burnout::happy1:
 
The shorter stroke of a 340 will make less torque then a 360 all else being equal. All else being equal the 360 is the better engine because of the longer stroke.

If you pull a valve cover that will give you the casting number of the head. But that will not tell you if its big valve or not. '71 was big valve so it if has original heads then big valve.

The best thing you can do to that 340 is swap in some lighter pistons. The stock 340 pistons are extremely heavy. EQ heads will give you quench but would require thick head gaskets with stock pistons because they stick up above the deck.

Bet you could sell that 340 for some serious money and then go build a killer 360 or stroker.
 
same engine except for bore and stroke....bore the 360 to 4.04...you got the same bore...so the big difference is the stroke......same heads ...same intakes...same camshafts...

as said...stock 340 pistons heavy...and will always be heavier then a 360 due to pin height or compression height...
 
As fastback said, if that's a virgin 71' you could get some really good money for it. Could even post a vin# of of it and see if it's a long lost engine from a members car.

There was a discussion on here yesterday about those very heads. I contend all 71' 340's came with 915 (last 3 digits) "J" castings, 2.02's of course. Would like to know what you find.

Would love to see some pics if and when you have time?
 
Thanks guys...all of those thoughts have crossed my mind! I have seriously considered posting the vin and dumping it. The money would certainly buy what I still need for a 360, and I do have 360 knowledge! For years people have always contended that the 340 was by far superior. My thought was the only reason that was the prevailing attitude, was because the 360 was never considered a serious hi-po motor! I do believe based on my own goals and desires and manner in which I intend to drive my car...the torque from a 360 would be better suited. Imay get the numbers off this engine and "shop it around" No real sense in denying a needy member a resto motor, just so I can say I have a 340 in my hot rod! just for the sake of knowing what kind of money could I potentially ask. I have $850 in it.
 
If you don't want to spend a lot of money just freshen up the 340, if it even needs it , clean up he heads , stick in a cam and have fun . If you want to try and be the ""fastest "" on the block build up the 360 .
Mhat I did , since I have 3 340's is keep the numbers matching in the garage , one I stuck 10.5 mahle coated pistons , cam , not sure which one is in it now , cleaned up the heads and ipso presto 413 hp 398 torque . Not sure what Ill do with the 3rd .
Seeing as you have the 340 it will not take much to get 400+ hp , not sure what you'll have to spend to get the 360 up there .
But people here have a hard on for the 360 , either way have fun with what you build
 
The 340 has the reputation because it came from the factory with a 4 barrel and high compression with dual exhaust where as the 360 was usually a low compression smogger 2 barrel. Put some good pistons in a 360 to bring compression up, decent heads, 4 barrel and the 360 is the stronger runner because of its lighter pistons and longer stroke. The 360 is a stroked 340.
 
lets not forget the early 340s have a forged crank, much stronger, and 340,s will rev higher with the shorter stroke. 360's all have cast cranks and in stock form a 340 will flat out run a 360. So in stock form the 340 is a much better engine!!!! Now...you can certinly build either one to be a monster, with stroker cranks, high compression pistons, etc. etc. I always get a kick out of these guys who want to compare a stock 340 to a stroker 360.....lets compare apples to apples.
 
fanofpetty said:
lets not forget the early 340s have a forged crank, much stronger, and 340,s will rev higher with the shorter stroke. 360's all have cast cranks and in stock form a 340 will flat out run a 360. So in stock form the 340 is a much better engine!!!! Now...you can certinly build either one to be a monster, with stroker cranks, high compression pistons, etc. etc. I always get a kick out of these guys who want to compare a stock 340 to a stroker 360.....lets compare apples to apples.
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I completely agree. Gotta love that 3.31 stroke, it's just cool at about 6,500.......lol.
 
Sell the 340 and fund the 360.
 
340 can be bored bigger than most 360's drop a aftermarket 360 crank into the bigger 340 bore you got the best of both engines.
 
meh......bore size has a minimal effect on power. For what he could sell the 340 for, He could have a dang nice 360. You gotta count the cost of cuttin the crank down to go in the 340, too.
 
Money spent build the 360.

FYI this weekend I am picking up a fresh build 340 long block
72 .030 340 for $1200 off a friend, he is going into the big "D" so just trying to help him out.
Don't need the engine.
Handshake between me and him is he can buy it back at tax time.
 
sireland67 said:
Money spent build the 360.

FYI this weekend I am picking up a fresh build 340 long block
72 .030 340 for $1200 off a friend, he is going into the big "D" so just trying to help him out.
Don't need the engine.
Handshake between me and him is he can buy it back at tax time.
Click to expand...

That's called "the redneck return clause" where I come from. It's a sacred agreement.
 
OldmanRick said:
I completely agree. Gotta love that 3.31 stroke, it's just cool at about 6,500.......lol.
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Yeah just got to love them 340's at 6500 rpm . On my Dart it gets really interesting between 4500 and 6500 . Have had mine up to 7,000 and it was still pulling , but I'm not into breaking it .
That's why I say just freshen up the 340 and you have a great street car .
As to the lighter pistons on the 360 , what kind of pistons we talking about ? Forged , cast ? I'm going to find the paper work on my 340 , now you got me interested in how much more my pistons weigh . Mahle .30 over 10.5 forged coated pistons , I was under the impression they were lighter than stock , will check it out
 
jerry6 As to the lighter pistons on the 360 said:
I think your right Jerry. Been a long time since i built one, but other then the old TRW/SpeedPro type replacements, i think most aftermarket forged are a little lighter then stock.
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Most of the education you got on hear Abbot 340 VS 360s is bull crap. No matter how you build them the 340 will run out run the 360.The only worth a 360 have is availability.The 340 is worth more to a person the needs one for restoring purposes.Yes it is better to build a 360 because there is more of them around.I built both engines and still the 340 was faster.One thing you have two engines doing two different things.The 360 is the start of TQ the 340 is HP the reason the 340 will out run the 360 is it has almost the TQ and and produce more HP.If you want the correct info I would try to find a old DC book and learn from there.The new books don't have all the info you need. Mark
 
dartcuda1 said:
Most of the education you got on hear Abbot 340 VS 360s is bull crap. No matter how you build them the 340 will run out run the 360.The only worth a 360 have is availability.The 340 is worth more to a person the needs one for restoring purposes.Yes it is better to build a 360 because there is more of them around.I built both engines and still the 340 was faster.One thing you have two engines doing two different things.The 360 is the start of TQ the 340 is HP the reason the 340 will out run the 360 is it has almost the TQ and and produce more HP.If you want the correct info I would try to find a old DC book and learn from there.The new books don't have all the info you need. Mark
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educate me on how a 340 will out run a 360..went they use the same heads, cams..and intake..exhaust headers.....and heads is where the horsepower is made...and how a 340 is going to out rev a 360 with a heavier pistons....is the 340 exempt from the laws of physics?

and i am not talking about a 71 HP 340 against a 74 low compression 360...lets talk apples to apples...both 10 to 1 compression with the same cam and same heads;;;;;

i have been racing 360s for decades with the same cast cranks that have turned up to 7500 rpm....so throw that BS out the window about the crank being weak...just for the uneducated..a cast crank is light then a forged crank...and the ET clocks dont know that it is a cast crank...

price out the parts for a 10.5 to 1 340...pistons are higher cost...rings are higher cost then 360....using all the same parts from there out since they are all interchangeable except oil pan...the 360 is cheaper to build to 400 hp...In fact..the 360 has alot more pistons options then the 340 does these days.....

I dont hate 340s....as I have 6 or 7 of them...i just want the biggest bang for the buck...the 360 is where its at...

Ok...but working all night...bed time..at 5 am PST
 
dartcuda1 said:
Most of the education you got on hear Abbot 340 VS 360s is bull crap. No matter how you build them the 340 will run out run the 360.The only worth a 360 have is availability.The 340 is worth more to a person the needs one for restoring purposes.Yes it is better to build a 360 because there is more of them around.I built both engines and still the 340 was faster.One thing you have two engines doing two different things.The 360 is the start of TQ the 340 is HP the reason the 340 will out run the 360 is it has almost the TQ and and produce more HP.If you want the correct info I would try to find a old DC book and learn from there.The new books don't have all the info you need. Mark
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A 360 built the same way as a 340 will win every single time, all other things equal. I don't know where you got your information, but I'm sorry, you're incorrect. The 360's longer stroke means it will have more bottom end torque, leaving the 340 off the line and the more cubes will keep it pulling ahead. As the old saying goes, there's no substitute for cubic inches. It holds true every time.
 
I've run both, built the same...the 360 has more torque off the line but the 340 has more of a top end charge. ET's are very similar. I like both, but prefer 340's well, because it's a 340. The name is a legend. It's also fun to beat on one at the track and make the people who say they are only for the resto crowd mad. When you say you have a 360 people look disappointed, lol.
 
stick to your legend and watch my tail lights dissappear.....an engine ability to make hp is in the cylinder heads..they both use the same head...
 
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