Facebook Click here to find out more!

Need help with a 340

  
Mopar Muscle
Item Posts    Sort Order

Need help with a 340

 
Duster1911 Duster1911
New User | Posts: 1 | Joined: 10/12
Posted: 10/15/12
01:55 PM

HI,
Im trying to get some applications on how to build a 500hp 340 for a 72 duster. My dad had it at first with a 318 but he changed it out and put a 340 but the engine was a regular engine and im wanting to get it back going any suggestions would be helpful on some combinations.  

RBolig RBolig
Moderator | Posts: 948 | Joined: 12/03
Posted: 10/16/12
08:02 AM

500 horsepower is going to require some good parts, and money.

For starters, stroke it 4 inches, add a steel crankshaft and H-beam connecting rods. Raise the compression ratio to about 11.0:1, add a good roller camshaft, a set of good heads, and the right intake and carburetor.  
--------------------


Some people are like Slinkys; they're not very useful, but fun to watch when pushed down the stairs.

IQ52 IQ52
Guru | Posts: 857 | Joined: 06/10
Posted: 10/16/12
10:53 AM

Here are a few engine builds with dyno sheets that will give you an idea of what it will take to get to approximately 500 HP. When the water issue was resolved the 273/292ci engine made 462 HP.

http://www.moparmusclemagazine.com/techarticles/engine_challenge/mopp_1106_2010_amsoil_mopar_muscle_engine_challenge/

The contest required the use of the Indy/RHS cylinder head. Other cylinder heads may be used such as the aluminum Edelbrock small block and other aftermarket aluminum heads or Mopar Performance W2 heads.

Perhaps the most important factor in a 500 HP build will be the cylinder heads.  

wyrmrider wyrmrider
New User | Posts: 5 | Joined: 01/13
Posted: 01/11/13
12:55 PM

amen to the Cylinderheads
cylinder heads are the limitation
all cu inches can make the same peak HP but at different RPM's
torque peak is also lower and you reach peak head flow at a lower rpm giving a broader torque curve
as said above it's easier with 400+ cu in than 340
DO NOT BORE any more than necessary to clean up
if running hyd roller you could use a 360 crank with mains ground to 340 size if a 4x4 kit is not in your budget
also if not on a budget for new rods the DC rod bolts are SPS and much less than ARP
with 340 cu inches you may need a solid roller and lots of compression, careful gasket selection
run a tight quench
do the cross oil mod, windage tray
stick shift? small hole through the crank thrust for full time oiling of the thrust  

marcohotrod340 marcohotrod340
Enthusiast | Posts: 461 | Joined: 09/08
Posted: 01/20/13
11:30 AM

if your 340 is a 1968-early 1972 with a steel crank, use it and put the money into the new Air Wolf 220cc heads that flow 320 cfm. with a solid roller like 262/266 @ .050" and an 850 carb and 11.5 comp. ratio on pump gas have 525hp. my 340 has run 11.5 and a solid street/strip 260/260 with a stick and no hole thru the thrust, DC rod bolts in blueprinted stock rods, no cross oil mod (just the oil to the far side lifters blocked) quench, and she go to 7000+ for the past 17 years and counting  

marcohotrod340 marcohotrod340
Enthusiast | Posts: 461 | Joined: 09/08
Posted: 01/20/13
11:36 AM

hey, what was the cause of the early demise of the old school valiant 408, did I miss the followup?  

Skwerly Skwerly
User | Posts: 76 | Joined: 02/10
Posted: 01/21/13
12:58 PM

it'd be waaaay cheaper to aim for 400hp but if you are set on 500, the advice here will get you there.  

duster1973 duster1973
New User | Posts: 3 | Joined: 04/08
Posted: 02/17/13
04:45 PM

My car runs 11.80's all day long, stock bottem end 1973 matching numbers block,good rod bolts all balanced. Brodix Spec heads just gasket matched. It ended up with 440hp on Dyno. 727 3500 stall 4.30 gears. Why are you set on 500 hp. Im building a 3.70 stroker now with all nos mopar performance parts it should yeild 600 hp due to the Brodix heads being ported.