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Re: Need advice 340 vs 360 in A body
[Re: repad]
#137674
10/16/08 05:32 PM
10/16/08 05:32 PM
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Anonymous
Unregistered
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Anonymous
Unregistered
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IMHO.....
Both engines are of identical proportions. One fits as well as the other.
Unless you have a 340 already on hand, locating one to rebuild can be difficult at times.....and costly.
360's are everywhere.....both the LA and Magnum versions.
Personally I would build up a new Magnum 360 for it.
Sid
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Re: Need advice 340 vs 360 in A body
[Re: Neil]
#137676
10/16/08 06:18 PM
10/16/08 06:18 PM
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Joined: Jun 2006
Posts: 5,159
CT
GTX MATT
master
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master
Joined: Jun 2006
Posts: 5,159
CT
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I would say go with a 340 thats in good running condition as long as its an early high compression engine before 72. Youll pay more but you can go with more as far as cam goes and get more power in the end. To get the compression up on the 360 youll have to rebuild it if you really want high compression. Shaving the heads on the 340 can net you over 10:1 as was advertised from the factory if it doesnt have it that high already. Itd also start you with a 2.02 intake valve.
A 340 long block might run you 1500 bucks, but its cheaper than a 300 360 core and the price of a rebuild.
If hes going to rebuild go with the 360 so long as he doesnt need a forged crank to spin it to the moon, which it doesnt sound like hes trying to do.
By the way did the 340 have forged pistons? I dont know as im usually into the big blocks, I remember somone saying that they did come with them though some how. I doubt Im remembering correctly but if they did thats another plus right there.
Last edited by GTX MATT; 10/16/08 06:20 PM.
Now I need to pin those needles, got to feel that heat
Hear my motor screamin while I'm tearin up the street
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Re: Need advice 340 vs 360 in A body
[Re: GTX MATT]
#137677
10/16/08 06:39 PM
10/16/08 06:39 PM
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Joined: Jan 2003
Posts: 7,978
Bethel Ct
AdamR
master
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master
Joined: Jan 2003
Posts: 7,978
Bethel Ct
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No forged pistons in stock 340s. In my opinion either motor is going to cost the same to rebuild. The 340 has a higher initial by in. The 360 core is much cheaper and the longer stroke will give you a bit more low end grunt. If you have a motor to start with build it, If not either one is capable of making a good street motor so buy which ever one you can get the better deal of. Most likely a 360. Matt if I had the extra cash I would pick that motor up from you. 
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Re: Need advice 340 vs 360 in A body
[Re: repad]
#137681
10/16/08 08:52 PM
10/16/08 08:52 PM
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Joined: Apr 2007
Posts: 2,826
NY usa
540challenger
master
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master
Joined: Apr 2007
Posts: 2,826
NY usa
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Quote:
He doesn't have an engine yet, so it looks like he'll be building a 360 since they are easier to find. An earlier poster mentioned using a Magnum over an LA, how can we tell the difference? Is there a good book on building smallblack mopars?
The easiest way to tell a magnum from a LA engine is the valve covers.
LA has 5 bolts per cover
MAg. has 10 bolts per covers.
There are a ton of small block moapr books out there know.
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Re: Need advice 340 vs 360 in A body
[Re: AdamR]
#137683
10/16/08 09:25 PM
10/16/08 09:25 PM
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Joined: May 2004
Posts: 679
N.E Indiana
repad
OP
super street
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OP
super street
Joined: May 2004
Posts: 679
N.E Indiana
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Quote:
Magnums have there pros and cons.
Hyd roller cam, Better heads but you will need a center sump oil pan, a LA timing cover and water pump, The cam isnt set up for mechanical fuel pumps but that cant be fixed with an aftermarket cam or bolt on snout. You also have to check the heads for cracks between the valves.
I can understand the need for a center sump pan but why an LA timing cover and water pump?
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Re: Need advice 340 vs 360 in A body
[Re: repad]
#137684
10/16/08 10:40 PM
10/16/08 10:40 PM
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Joined: Sep 2007
Posts: 14,889
up yours
Supercuda
About to go away
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About to go away
Joined: Sep 2007
Posts: 14,889
up yours
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Quote:
I can understand the need for a center sump pan but why an LA timing cover and water pump?
To make room for the extended snout on the camshaft. when Chrysler did away with mechanical fuel pumps they also shortened the cam and on the Magnums they shortened the timing chain cover. The pump was redesigned for th enew Magnum cover and won;t work properly on an LA cover.
Don;t forget accesories. You are not likely to want to run the Magnum accesories, especially if you run the LA cover. You may have alignement issues running LA accesories on a Magnum block, just check them when you build the engine.
As for 340 vs 360, assuming both need rebuilt, r both don't, my recommendation is this. Street - 360, strip - 340.
360 has a longer stroke, builds more torque, all else the same. Torque is better for a street car.
340 has a shorter stroke, will rev up quicker and be happier higher up making more HP, all else equal. HP is the ticket for the strip.
Be an interesting dyno test if you took a 340 and a 360, built them the same (compression, heads, cam, etc) and see what they did.
They say there are no such thing as a stupid question.
They say there is always the exception that proves the rule.
Don't be the exception.
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Re: Need advice 340 vs 360 in A body
[Re: Supercuda]
#137685
10/16/08 11:36 PM
10/16/08 11:36 PM
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Joined: Jan 2003
Posts: 9,826
las vegas
70AARcuda
master
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master
Joined: Jan 2003
Posts: 9,826
las vegas
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Quote:
Quote:
I can understand the need for a center sump pan but why an LA timing cover and water pump?
To make room for the extended snout on the camshaft. when Chrysler did away with mechanical fuel pumps they also shortened the cam and on the Magnums they shortened the timing chain cover. The pump was redesigned for th enew Magnum cover and won;t work properly on an LA cover.
Don;t forget accesories. You are not likely to want to run the Magnum accesories, especially if you run the LA cover. You may have alignement issues running LA accesories on a Magnum block, just check them when you build the engine.
As for 340 vs 360, assuming both need rebuilt, r both don't, my recommendation is this. Street - 360, strip - 340.
360 has a longer stroke, builds more torque, all else the same. Torque is better for a street car.
340 has a shorter stroke, will rev up quicker and be happier higher up making more HP, all else equal. HP is the ticket for the strip.
Be an interesting dyno test if you took a 340 and a 360, built them the same (compression, heads, cam, etc) and see what they did.
awwhhh...the old 340 is going to rev faster theory again...ever weight a stock 340 piston and pin....together they weigh over 800 grams...
Tony
70 AARCuda Vitamin C
71 Dart Swinger 360 10.318 @ 128.22(10-04-14 Bakersfield)
71 Demon 360 10.666 @122.41 (01-29-17 @ Las Vegas)
71 Duster 408 (10.29 @ 127.86 3/16/19 Las Vegas)
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Re: Need advice 340 vs 360 in A body
[Re: goldmember]
#137687
10/17/08 12:04 AM
10/17/08 12:04 AM
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Joined: Jan 2003
Posts: 25,200
Upper Midwest
MoparforLife
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 25,200
Upper Midwest
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Quote:
360 everytime!!!
If the 360 would have been built instead of the 340 with the same specs as the early 340 no one would even bring the 340 up.
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Re: Need advice 340 vs 360 in A body
[Re: repad]
#137689
10/17/08 07:26 AM
10/17/08 07:26 AM
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Joined: Jan 2003
Posts: 7,978
Bethel Ct
AdamR
master
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master
Joined: Jan 2003
Posts: 7,978
Bethel Ct
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Quote:
I can understand the need for a center sump pan but why an LA timing cover and water pump?
Magnums also dont have the mechanical fuel pump boss and the water pump is reverse rotation I believe.
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Re: Need advice 340 vs 360 in A body
[Re: Supercuda]
#137691
10/17/08 08:27 AM
10/17/08 08:27 AM
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Joined: Feb 2003
Posts: 4,204
Fort Worth, TX
Clair_Davis
master
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master
Joined: Feb 2003
Posts: 4,204
Fort Worth, TX
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Quote:
To make room for the extended snout on the camshaft. when Chrysler did away with mechanical fuel pumps they also shortened the cam and on the Magnums they shortened the timing chain cover. The pump was redesigned for th enew Magnum cover and won;t work properly on an LA cover.
...
Don;t forget accesories. You are not likely to want to run the Magnum accesories, especially if you run the LA cover. You may have alignement issues running LA accesories on a Magnum block, just check them when you build the engine.
Beg to differ on this one. The Maggie cover is actually DEEPER than the LA. I measured both when I was swapping Magnum accessories on to my 340, and I wanted to leave the fuel pump eccentric on my cam. Worked just fine.
What DIDN'T work were the Maggie accessories. The LA blocks don't have the bosses that the Maggies do to mount the PS pump and tensioner, so you have to do a bit of fabrication to make them work. I won't likely do Maggie parts on an LA block again. It's just too easy to start with a Maggie block. I suspect, but can't prove, that LA accessories work just fine on a Maggie, once the TC/WP is swapped out.
Clair
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