Build a new 340, or stick in a Gen 3 Hemi
#837874
10/24/10 09:48 PM
10/24/10 09:48 PM
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Joined: Jan 2003
Posts: 3,719
Space Station #5
471Magnum
OP
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OP
master
Joined: Jan 2003
Posts: 3,719
Space Station #5
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Got a 72 Roadrunner factory 340 auto car. Motor has some issues, not the least of which are a harmonic vibration, and a missing corner of the block leaving short a transmission dowel. All that is a topic for another thread. Bottom line though, I need to put a new motor together in the not too distant future.
As an alternative, I've been toying with the prospect of installing a Gen 3 Hemi.
Surfed through the archives, but really didn't come across a good complete parts and price list to to a budget friendly swap. If anyone has a complete list of required parts, I'd love to see it. If I missed it in my search, shoot me a link.
In my case, I think I want to stick with my fresh 727TF and run a carburetor. Might upgrade those areas down the road, but phase one would have to be completed on the cheap.
In addition, it's an N96 car and keeping that functional is mandatory. Not sure how a carbureted Hemi compares to a 340 height wise, but I suspect it's shorter.
-Jim
I can fix it... my old man is a television repairman.
He's got the ultimate set of tools... I can fix it.
Currently Mopar-less
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Re: Build a new 340, or stick in a Gen 3 Hemi
[Re: 471Magnum]
#837875
10/24/10 10:15 PM
10/24/10 10:15 PM
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Joined: Nov 2008
Posts: 301
wisconsin
swifter
enthusiast
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enthusiast
Joined: Nov 2008
Posts: 301
wisconsin
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Want 3 g info head to for a body's only under new hemi thread will answer all your questions
2007 Ram 2500 Cummins
2008 Dodge Nitro
1970 340 Valiant Duster
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Re: Build a new 340, or stick in a Gen 3 Hemi
[Re: swifter]
#837876
10/25/10 09:22 AM
10/25/10 09:22 AM
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Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
patrick
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
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I really like the 3G hemi's, great head flow makes great power with pretty mild cams.... but if I were going that way, I'd keep the EFI....the exhaust, oil pan, and ignition (if going carb) are expensive retrofitting, really now way around it...
what I think would be easier/cheaper route with good power production would be start with a magnum 360 block, depending on budget & how fast want to go, I'd use KB107 pistons, Enginequest or RHS magnum heads, eddie RPM air gap, a cam like the comp XR274HR or XR280HR, headers, and a 750-800cfm carb. should be a ~400hp-425hp/420-450tq motor...
Last edited by patrick; 10/25/10 09:25 AM.
1976 Spinnaker White Plymouth Duster, /6 A833OD
1986 Silver/Twilight Blue Chrysler 5th Ave HotRod **SOLD!***
2011 Toxic Orange Dodge Charger R/T
2017 Grand Cherokee Overland
2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)
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Re: Build a new 340, or stick in a Gen 3 Hemi
[Re: patrick]
#837877
10/25/10 02:14 PM
10/25/10 02:14 PM
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Joined: Jan 2003
Posts: 3,719
Space Station #5
471Magnum
OP
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OP
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Space Station #5
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The top end on my 340 is still good. Everything is quiet. No smoke. No oil consumption. Nothing that concerns me (other than the vibration). I'm just looking at building a new short block and installing a new cam kit at this point. I'll probably have $2500 invested right there. Maybe less if my current motor has internals worth re-using.
Down the road, I might upgrade the heads. I really don't even know what's been done to them already. All I know is that they are J-castings and seem to be in good working order. I'm not inclined to mess with them.
Nothing has been apart yet, so this is all speculation.
I had pretty much tossed aside any thoughts of a Gen 3 hemi after looking into one for another project, but I figured I'd revisit the topic as a reality check.
-Jim
I can fix it... my old man is a television repairman.
He's got the ultimate set of tools... I can fix it.
Currently Mopar-less
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Re: Build a new 340, or stick in a Gen 3 Hemi
[Re: patrick]
#837878
10/25/10 03:00 PM
10/25/10 03:00 PM
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Joined: Aug 2007
Posts: 1,819
Middle of A Field
OrangeProwler
top fuel
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top fuel
Joined: Aug 2007
Posts: 1,819
Middle of A Field
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Quote:
I really like the 3G hemi's, great head flow makes great power with pretty mild cams.... but if I were going that way, I'd keep the EFI....the exhaust, oil pan, and ignition (if going carb) are expensive retrofitting, really now way around it...
what I think would be easier/cheaper route with good power production would be start with a magnum 360 block, depending on budget & how fast want to go, I'd use KB107 pistons, Enginequest or RHS magnum heads, eddie RPM air gap, a cam like the comp XR274HR or XR280HR, headers, and a 750-800cfm carb. should be a ~400hp-425hp/420-450tq motor...
Also, wouldn't the 360 Magnum have more torque especially on the bottom end? I mean the Hemi would shine up top. I'm not sure if you are aware of this thread but, I found this one useful for myself.
http://www.dodgecharger.com/forum/index.php/topic,62589.0.html
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Re: Build a new 340, or stick in a Gen 3 Hemi
[Re: OrangeProwler]
#837879
10/25/10 04:10 PM
10/25/10 04:10 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:
Quote:
I really like the 3G hemi's, great head flow makes great power with pretty mild cams.... but if I were going that way, I'd keep the EFI....the exhaust, oil pan, and ignition (if going carb) are expensive retrofitting, really now way around it...
what I think would be easier/cheaper route with good power production would be start with a magnum 360 block, depending on budget & how fast want to go, I'd use KB107 pistons, Enginequest or RHS magnum heads, eddie RPM air gap, a cam like the comp XR274HR or XR280HR, headers, and a 750-800cfm carb. should be a ~400hp-425hp/420-450tq motor...
Also, wouldn't the 360 Magnum have more torque especially on the bottom end? I mean the Hemi would shine up top. I'm not sure if you are aware of this thread but, I found this one useful for myself.
http://www.dodgecharger.com/forum/index.php/topic,62589.0.html
The new hemi have a nice amount of torque i am trying to find specs on a 5.9 magnum
G1 5.7 G1 5.7 G2 5.7 G2 5.7 G2.1 5.7 6.1 SRT8 6.4 ( Torque
375 @ 4,400 390 @ 4,000 407 398 @ 4,200 410 420 @ 4,800* 460Read more at http://www.allpar.com/mopar/new-mopar-hemi.html?ktrack=kcplink
I would imagine any upgrade inthe cam would bring the peak torque normals up higher on the power band
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Re: Build a new 340, or stick in a Gen 3 Hemi
[Re: 540challenger]
#837880
10/25/10 04:32 PM
10/25/10 04:32 PM
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Joined: Jan 2003
Posts: 3,719
Space Station #5
471Magnum
OP
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OP
master
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Posts: 3,719
Space Station #5
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I'm not so much interested in the ultimate performance potential (although I will make sure it runs strong) as the economics.
Let's not get off track debating which is better performance-wise. Both can make a ton of horsepower, but that's not a major concern in this application.
-Jim
I can fix it... my old man is a television repairman.
He's got the ultimate set of tools... I can fix it.
Currently Mopar-less
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Re: Build a new 340, or stick in a Gen 3 Hemi
[Re: 540challenger]
#837881
10/25/10 04:41 PM
10/25/10 04:41 PM
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Joined: Jul 2010
Posts: 11
N.E. Pa.
8657hemi
member
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member
Joined: Jul 2010
Posts: 11
N.E. Pa.
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If it's the original engine I'd keep the 340. Hemi swaps are nice but doing it on a low budget isn't going to happen. I've done four of them and you should expect to spend between 6 to 9k minimum. I know it's e-body related but here's a link that will give you some insight on the hemis. https://board.moparts.org/ubbthreads/showflat.php?Number=3930520
'86 D150 -'03 5.7 Hemi
'72 Charger - '08 5.7 Hemi
'73 Barracuda - '08 5.7 Hemi
'73 Challenger - '08 5.7 Hemi
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Re: Build a new 340, or stick in a Gen 3 Hemi
[Re: 8657hemi]
#837882
10/25/10 08:45 PM
10/25/10 08:45 PM
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Joined: Nov 2003
Posts: 3,106
Ridgeland Wi
mopars_1
master
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master
Joined: Nov 2003
Posts: 3,106
Ridgeland Wi
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a classic muscle car deserves a classic muscle engine! When I look under the hood of an old mopar, I want to see a nice small or big block. Id stay with the 340, the 3rd gen hemis are really getting over done in the old mopars IMO.
1971 Plymouth Duster 340 auto
1937 Plymouth PT50
1969 Dodge Dart Swinger 340 4 speed
2013 Ram laramie 2500 hemi
2008 Harley FLSTSB springer
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