Building first 340.. Any pointers?

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hoohaadart

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Hi.
I'm building a 340 for my 70 Dart. I have never even built a mopar motor before, only sbc. I'm looking for any pointers, things to stay away from, good cam choices, things like that. The block that I got does need a sleeve in #6 cylinder, but other than that, it's good. I have J heads, and since I am not building a track car, am stuck between using them, or getting aluminum heads. Any combination of parts that have been found to work really well together? Car is a 4 speed car, and I don't know yet what gears I will be running in the rear. Thanks!
 
It really depends on what your going to do with the car. I built my 340 for a street/strip motor but the car will never see the track, so I over built it to withstand anything stupid I want to do with it. If you want so spec of my 340 let me know.
Also Welcome to the club!
 
I would like to know what you used.....I'm in comparison mode right now...Also how "street friendly" is it? If you running adj. rockers how often you have to adjust? How much h.p and tq do you think you have?
 
An example is my build i guess

Comp 268 XE cam
Stock Crank
Eagle I Rods
KB pistons
.30 overbore
Dougs headers
RPM Air Gap
Holley 750 Vac Sec
Stock O heads with 2.02 valves


Dynoed at 333hp 367 tq
I wasnt looking for anything crazy as this is my first build as well. Next build is going to
be a big hp motor

If there is anything i forgot just ask

hope this helps
justin
 
mine has a 4 speed with 3.55 gears and drives on the street fine. When it wants to go it does.
 
I had problems with headers, bell housing and oil pan fitting on my 340 in my Duster. Headman headers, Lakewood bellhousing, Milodon oil pan. Than when we tried to drop motor and trans in from hood the k frame had to be cut, last time I removed motor and trans from the bottom of the car. I will never drop the motor in from the top again. I hope this helps and welcome to the site.
 
I'm in the middle of assembling a 340 with Brians rhs indy heads ,comp xe275hl ,stock 10-1, airgap and some bodies headers with a 4spd. Brian said at least 430hp. Boy i cant wait to dump the clutch
 

I had the rotating assembly balanced in my 340, best money I spent on the engine build....nothing like cruising the Interstate at 70 mph, 340 running at 4,500 rpm for an hour at a time....real smooth 8)
 
Here are my specs for my 340 (remember I OVER built my motor)
SFI Balancer and Flexplate
Comp Roller Rockers and Roller Cam
Hughes Roller Lifters and Stud Girdle
Ross Racing Forged Alum Pistons
Total Seal Gapless Piston Rings (File Fit)
Eagle Forged Crank (3.31) and Forged H-Beam Rods (6.123)
High Volume Water and High Volume Oil Pump
Milodon 7qt Oil Pan and Extended Pickup Tube
Edelbrock Alum Intake Performer RPM Air Gap
MSD E-Curve Distributor with built in Rev Limiter (Set at 6500 RPMs)
X-Heads with Ferrea Stainless Steel Intake and Exhaust Valves (Single Groove Stems)
Be Cool Alum Radiator with Dual Elec Fans
Full TTi Exhaust
All bolted together using the Strongest ARP bolts that will bolt to the motor.

I think that is it but ask any questions I'll try to answer them the best I can.
 
1970Duster said:
Here are my specs for my 340 (remember I OVER built my motor)
SFI Balancer and Flexplate
Comp Roller Rockers and Roller Cam
Hughes Roller Lifters and Stud Girdle
Ross Racing Forged Alum Pistons
Total Seal Gapless Piston Rings (File Fit)
Eagle Forged Crank (3.31) and Forged H-Beam Rods (6.123)
High Volume Water and High Volume Oil Pump
Milodon 7qt Oil Pan and Extended Pickup Tube
Edelbrock Alum Intake Performer RPM Air Gap
MSD E-Curve Distributor with built in Rev Limiter (Set at 6500 RPMs)
X-Heads with Ferrea Stainless Steel Intake and Exhaust Valves (Single Groove Stems)
Be Cool Alum Radiator with Dual Elec Fans
Full TTi Exhaust
All bolted together using the Strongest ARP bolts that will bolt to the motor.

I think that is it but ask any questions I'll try to answer them the best I can.
Click to expand...

What HP and Torqu #'s are you producing w/your setup?
 
hoohaadart said:
Hi.
I'm building a 340 for my 70 Dart. I have never even built a mopar motor before, only sbc. I'm looking for any pointers, things to stay away from, good cam choices, things like that. The block that I got does need a sleeve in #6 cylinder, but other than that, it's good. I have J heads, and since I am not building a track car, am stuck between using them, or getting aluminum heads. Any combination of parts that have been found to work really well together? Car is a 4 speed car, and I don't know yet what gears I will be running in the rear. Thanks!
Click to expand...
while its at the shop getting that sleeve put in, make sure the deck are square & the crank saddles are where it should be. 340's usually lived a hard life LOL.
 
Don't know yet cuz I haven't finished the car yet (I like wheel dynos better because, you can have all the hp and tq in the world but doesn't mean jack if isn't putting down at the wheels) but I would guess 400+ hp and 350+ tq (roller cam help a lot with torque because they come on earlier and stay on longer then stand flat tappet cams).
 
just got the numbers off the dyno for my 340 ,389 HP 412 lbs torque , .20 over mahle 10:5.1 forged pistons , forged crank , heads were worked a little and a mild cam , air gap intake with a holley 750 . Should be good for the street .

If you want complete specs I can get them for you . Will be at the shop saturday
 
Oh yeah I almost forgot, this setup will safely allow you to procharge the engine without a problem (just got to have the piston ring filed a little different)
 
6dart9 said:
An example is my build i guess

Comp 268 XE cam
Stock Crank
Eagle I Rods
KB pistons
.30 overbore
Dougs headers
RPM Air Gap
Holley 750 Vac Sec
Stock O heads with 2.02 valves


Dynoed at 333hp 367 tq
I wasnt looking for anything crazy as this is my first build as well. Next build is going to
be a big hp motor

If there is anything i forgot just ask

hope this helps
justin
Click to expand...

What was the overall cost and how in ya opinion would that price compare to a 360 build of similiar nature? How do you think the performance would compare between the two?
 
This Bad Demon said:
What was the overall cost and how in ya opinion would that price compare to a 360 build of similiar nature? How do you think the performance would compare between the two?
Click to expand...

Performance with identical heads I give the 360 an edge based on more cubes/stroke and tq.

Cost would be about the same. Might be more for the 360 if the 340 already has a forged crank and you want the same for the 360 as all 360's came with cast cranks. Truth be told that 360 cast crank will hold up to about 550 hp and is waaaaaaaay lighter than a forged unit.
 
Best investment. Go and buy the Mopar small block engine book from Dodge. Then follow what they recommend. Read it. The factory engineers know what their doing.
 
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