340 power

[8vettes]

Consult for you guys who have experience with 340 engines let me know what I could comfortably get out of my 340 and still keep it extremely reliable and try trouble free motor I would assume approximately 400 horse would be relatively easily obtained out of one of these I’d like to hear your thoughts and ideas and experiences with this motor. The one I’m looking at is a 72 but I’m willing to put money into this engine to increase the compression to get the horsepower that I’m looking for thanks in advance for your opinions and ideas.

 

[Hilljack68]

I've had a couple 340s in B Bodies. Just my opinion... except for the Hemi, the best engine Ma Mopar ever produced. The power-to-weight ratio is far better than most big blocks. And they're high-revvers!

Every 20 lbs of weight reduction is like adding 10HP. The 340 weighs 145 lbs less than a 440. I know the 440 is a torque monster, but that little 340 is tough to beat. The one in my Coronet is just a mild build, but I'm at about 360HP. So your goal of 400HP shouldn't be hard to achieve.

 

[hunt2elk]

Put a stroker kit in it, and you will safely/easily be knocking on a 500 hp motor.

 

[toolmanmike]

Put a stroker kit in it, and you will safely/easily be knocking on a 500 hp motor.

If built right.

 

[Jerry Hall]

Although I have several 340's laying around, I don’t have much experience or history with them. One of my best friends that I have known for over 30 years was a small block guy when we met. He built what he called a 340 6-pack, but it was actually a 360 de-stroked to a 340 or thereabouts, with 6-pack carburetors. I don't know many specifics on the build, but I sold him some 273 adjustable rockers for the 340 X heads he had. The dyno said 464 HP and right at 400 torque.

 

[autoxcuda]

Much more cost effective to buy a 360 motor. Then put a 4" stroker kit in it when rebuilding it. It will come to 410 cid. vs a 340 block that is 419" cid.

You will never feel those 9 cubic inches of difference on the street. The only visual difference is the casting number that is going to be mostly covered by your exhaust manifold or headers.

But if you already have a 340, run it.

A 4" stroke kit 450 horsepower / 450-475 torque motor is plenty for street tires and should have decent vacuum for power brakes and easier to tune and keep tuned. And still run pump 91 octane with 9.5:1 to 9.7:1 compression. Look at cams with around 235 to 240 duration at 050. And about .500" to .525 lift with 110 to 112 lobe separation. You can run that with hydraulic lifters and stock rockers. run an edelbrock RPM or Air-Gap intake with 750 double pumper. Lots of street fun.

 

[Diodedog]

Put a stroker kit in it, and you will safely/easily be knocking on a 500 hp motor.

Not without aftermarket heads or some serious porting on the stock ones.

 

[autoxcuda]

Not without aftermarket heads or some serious porting on the stock ones.

Even without porting, a decent stock 2.02 head X or J has potential for 400-450 hp street motor. With gobs of torque and throttle response.
1 hp/1cid to 1.07hp/1cid.

 

[hunt2elk]

.

 

[hunt2elk]

Not without aftermarket heads or some serious porting on the stock ones.

Yeah, forgot to mention that. Had a 360/408 with worked over heads that dyno'd at 489 hp. That was a fun motor.

 

[wish4hemi]

Much more cost effective to buy a 360 motor.

Much more cost effective to buy a Gen 3 Hemi motor. I don’t understand why guys are still wasting money on small block or even big block wedge motors. The Eagle Hemi platform blows those old engines out of the water in every way. And if you can step up to a 6.4L, then the gap gets even bigger.

I’m not saying you need the fuel injection or a late model transmission. Run a G3 Hemi with a carburetor and your old 904/727/833 transmission. The G3 Hemi is the superior engine no matter how it’s fed fuel and what transmission it’s connected to.

 

[Diodedog]

Even without porting, a decent stock 2.02 head X or J has potential for 400-450 hp street motor. With gobs of torque and throttle response.
1 hp/1cid to 1.07hp/1cid.

Yes, but 500HP is another story.

 

[Hilljack68]

I don’t understand why guys are still wasting money on small block or even big block wedge motors. The Eagle Hemi platform blows those old engines out of the water in every way.

Because the cool factor of the old engines is far superior to the new ones. That new gen Hemi doesn't sound, smell or feel like the old iron. Too each his own, but we're not "wasting our money"... we're savoring raw Mopar flavor.

Steve Vai is a better guitarist than Joe Walsh, but I'll put on the James Gang every time over Mr. Vai.

 

[forphorty]

I've had a couple 340s in B Bodies. Just my opinion... except for the Hemi, the best engine Ma Mopar ever produced. The power-to-weight ratio is far better than most big blocks. And they're high-revvers!

Every 20 lbs of weight reduction is like adding 10HP. The 340 weighs 145 lbs less than a 440. I know the 440 is a torque monster, but that little 340 is tough to beat. The one in my Coronet is just a mild build, but I'm at about 360HP. So your goal of 400HP shouldn't be hard to achieve.

20 lbs of weight reduction is NOT like adding 10 hp. Not even close. More like 100 lbs.

 

[Runcharger]

I love the 340's and have had a couple that really cooked back in the day.
Today though I would do the stroker crank in a 360 block and aftermarket heads as well.

 

[HemiSuperBee]

I have a day 2 type 340 almost ready for assembly in the shop. LD340. Hyd. Roller. Stock 894 heads. Going to try to talk him into a dyno day. I am curious about it.

 

[Diodedog]

Because the cool factor of the old engines is far superior to the new ones. That new gen Hemi doesn't sound, smell or feel like the old iron. Too each his own, but we're not "wasting our money"... we're savoring raw Mopar flavor.

Steve Vai is a better guitarist than Joe Walsh, but I'll put on the James Gang every time of Mr. Vai.

Check out James Gang Live, Joe at his best.

 

[71Beeper]

Yes, it can be done.
My .030 over 360 with 340 'J' heads made 465hp and 485 ft lbs on the dyno.

But the heads will need some work. Mine have the 2.02/1.88 set-up and have been shaved to get a 60cc chamber.
Block has been zero decked with a KB107 piston. Compression is 10.9:1.
Cam is solid Isky with a .550 lift / 270 duration with Harland Sharpe 1:6 rockers.
Air Gap intake with 800 Holley.

 

[dvw]

340/360 either will work. My street Challenger 360; stock crank and rods, 9.0-1, ported factory heads, [email protected]" hyd roller, LD340 intake, 650 Holley, TTI headers and 2 1/2" exh, 3.55, 4 speed. With sticky tires 12.7@109. Freshening a 360 based 408 stroker right now. Solid roller, single plane,Trick Flow CNC 190 heads, 12.5-1. It runs 10.30's in a Duster thru the mufflers.
Doug