340 or 408

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Fisher

Old Guy with a Cool car.
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I know the 340 is a classic and the 408 is a torque monster. But something about the sound of a 340 spinning to 6800 rpm.

The plan was to build an aluminum head 340 with 10.25-1 compression pump gas deal with solid lifter cam. looking for 400 hp.

The Motor i am getting is a low mile 340 out of a 73-74 duster that rolled. I am not sure whats in there for components, but when did they stop putting a steel crank in the 340? My engine builder says we will use a better aftermarket rod anyway as well as a forged piston. The only thing we are missing in the end is a stroker crank. So i am torn between 340 or 408? I am spending the majority of the money anyway, so whats another $600 for a crank. The rest of the drivetrain will be 2500-2800 stall converter with 3.55 limited slip.

What is the smart way to go here?:happy1:
 
I know the 340 is a classic and the 408 is a torque monster. But something about the sound of a 340 spinning to 6800 rpm.

The plan was to build an aluminum head 340 with 10.25-1 compression pump gas deal with solid lifter cam. looking for 400 hp.

The Motor i am getting is a low mile 340 out of a 73-74 duster that rolled. I am not sure whats in there for components, but when did they stop putting a steel crank in the 340? My engine builder says we will use a better aftermarket rod anyway as well as a forged piston. The only thing we are missing in the end is a stroker crank. So i am torn between 340 or 408? I am spending the majority of the money anyway, so whats another $600 for a crank. The rest of the drivetrain will be 2500-2800 stall converter with 3.55 limited slip.

What is the smart way to go here?:happy1:

Well, in the other forged vs cast thread the guy was looking for 500hp. But if you goal is 400hp I think that is well within the relm of cast crank needs.

I bet it would be less that $600 more for a stroker crank when you figure machining your old 340 crank.

But the 416" stroker (w/340 block) is cheap hp/$. The cheapest if you are looking for streetablity and not a big "acting" cam.

My 416 revs surprisingly quick. I have a comp 274-S small solid cam. I'm probably at 430-450 hp. Very streetable to drive to the grocery store in it which I do.

What solid cam are you looking at for your 340? A stroker sort of "soaks up" cam. Very generally speaking, you can go up one notch hotter cam and it typically will behave like a 340 with a notch lower cam.

66 more cubic inches with one size bigger cam, could give you about 50 hp gain.

Here's my 416 idling with TTI hearders/X pipe/full exhaust, comp 274-S solid cam, Edelbrock heads, M1 single plane.

[ame="http://www.youtube.com/watch?v=-8QSTlvdqSs"]416 Idling sound walk around - YouTube[/ame]
 
I am looking at a Lunati solid cam. .526/.546 lift .235/.243@.050 on a 110 LSA. i can get a scatt rotating kit withKB pistons for $1425.00
 
I would cast my vote for the 416 as well. I have a mild build; X-Heads with a little bowl work and stock exhaust manifolds. The car is very streetable and smooth all the way up to 5800 RPM when it can't pump any more air because of the restrictive exhaust manifolds. I ran high 12's with 3:55's but really more of a cruiser.

[ame="http://www.youtube.com/watch?v=DrKBbVmQVf0&feature=share&list=ULDrKBbVmQVf0"]050711 Dart 013.MOV - YouTube[/ame]
 
I know the 340 is a classic and the 408 is a torque monster. But something about the sound of a 340 spinning to 6800 rpm.

The plan was to build an aluminum head 340 with 10.25-1 compression pump gas deal with solid lifter cam. looking for 400 hp.

The Motor i am getting is a low mile 340 out of a 73-74 duster that rolled. I am not sure whats in there for components, but when did they stop putting a steel crank in the 340? My engine builder says we will use a better aftermarket rod anyway as well as a forged piston. The only thing we are missing in the end is a stroker crank. So i am torn between 340 or 408? I am spending the majority of the money anyway, so whats another $600 for a crank. The rest of the drivetrain will be 2500-2800 stall converter with 3.55 limited slip.

What is the smart way to go here?
:happy1:

408 will work a lot better with that low stall and street gears. the 340 would need 3500-4000 stall minimal and 4.56 gears to work.

Go 408!!
 
Built a 408,responsive sucker.My vote goes that way,if the budget tolerates.If I recall correctly,72 last year for steel crank 340 's.
 
Why not wait to see whats in your 340 block first? Maybe someone stuck a forged crank in a later block, and maybe had the rotating assembly balanced already and put good pistons in, you could already be sitting on some good stuff. Kinda just depends on what you got and what you want. No doubt the strokers run well but it aint that hard to put a streetable 340 in the 12s, how fast you wanna go?
 
I agree with "bomber" and the others. With a tight converter and that rear gear the stroker is the way to go. Crank wise it wont matter if you go 4". Some say the late 72' 340's were cast, but i still believe that the 72' production cars were all forged. All 73's were cast. There were no 340's in 74' only 360's.
 
Got 428 HP 405 TQ out of my 10.5:1 eddy headed 340 with a XE282S cam. Dont have the torque of a stroker. Fun quick revving engine. But now going to build a stroker to get more torque and turn less rpms
 
A 400hp 340 will make that at 5800-6000 a 416 gonna make that about 600rpm less, the 416 gonna make about 60 lb-ft more than a 340 so if both engine are gonna run 3.55:1 gears the 416 will run stronger but if you go 4.10:1 for the 340 the torque to the ground would be the same. If your going with auto and 3.55 gear I'd go 416, personally I'd do a 4 gear swap and 4.10 and keep it 340.
 
Actually,273.The spreads drop 1k on hp ,and tq peaks,by personal experience.
 
I would cast my vote for the 416 as well. I have a mild build; X-Heads with a little bowl work and stock exhaust manifolds. The car is very streetable and smooth all the way up to 5800 RPM when it can't pump any more air because of the restrictive exhaust manifolds. I ran high 12's with 3:55's but really more of a cruiser.

050711 Dart 013.MOV - YouTube

Dusterndart340 what cam are you using.
 
I agree with "bomber" and the others. With a tight converter and that rear gear the stroker is the way to go. Crank wise it wont matter if you go 4". Some say the late 72' 340's were cast, but i still believe that the 72' production cars were all forged. All 73's were cast. There were no 340's in 74' only 360's.

I have a 72 340 block in my Valiant, it had a cast crank so I went with a 70 340 crank I had instead, tucked the 72 crank away for future use if needed.
 
I agree with "bomber" and the others. With a tight converter and that rear gear the stroker is the way to go. Crank wise it wont matter if you go 4". Some say the late 72' 340's were cast, but i still believe that the 72' production cars were all forged. All 73's were cast. There were no 340's in 74' only 360's.

I have a 72 340 block in my Valiant, it had a cast crank so I went with a 70 340 crank I had instead, tucked the 72 crank away for future use if needed.

Well there you go. Guess i should have phrased my quote as "i believe most 72' 340's were forged". Would really like to know the real story behind those that got out late, other than "they just must have run out" of forged. I know there were other threads about this, but i don't remember a concensus being reached. As far as the OP, just make sure what you're getting. Oh, and we love pics :D.

P.S. Did some more reading and it looks like Apr 72' and later 340's did indeed switch to Cast cranks. Dave Moore "dmoore" also had one, so i stand corrected.
 
Thank you for all the replies, lots of good info. I have been a Chevy guy for a lot of years, and the 350 is the basic work horse of the lineup. But once the 383 sbc hit the streets the war was on. I don't want to be the guy that gets grief for stroking an old 340 lol too many purists around here it seems. The 408 stroker makes the most sense for the gear and converter combo I am going with, as well I am only looking to run mid to low 12's with the car. I had a 9 sec street car, and have had enough of that crap. I want a cool old street car to have some fun with the way it used to be.
 
Will be getting that 340 and 727 pretty guick, will get it on the engine stand knock it apart and see what's in it for parts? It runs nice, I might just pull off one main and one rod cap look at the bearings see what they look like and put the pan back on for now? Determine if its a cast or steel crank etc go from there ?
 
Why not wait to see whats in your 340 block first? Maybe someone stuck a forged crank in a later block, and maybe had the rotating assembly balanced already and put good pistons in, you could already be sitting on some good stuff. Kinda just depends on what you got and what you want. No doubt the strokers run well but it aint that hard to put a streetable 340 in the 12s, how fast you wanna go?

Not bad advice right there. I planned to stroke (416) my 72 340 when I first bought the Duster last year. But upon opening her up, I was surprised/happy to find it already had a forged crank, was balanced and running 10.2 KB pistons. Have yet to get to the strip but it runs strong w zero traction through 1st and most of 2nd. My daughters & I plan on adding a 3.90-4.11 gear set, subframe connectors and slicks. If we break into the low 13's-Hi 12's with this combo we'll be very happy.

That said, our long term plans are to stroke the 340 to 416, aluminum heads etc....

Good luck with whatever course you take, and I look forward to following your progress.

Pat
 
If you can swing it go for the stroker
You cannot compare a stroked chevy to
A mopar.
383's are like belly buttons everyone has one.
 
I guess the question i was asking is... Is the 340 a rare engine, getting harder to come by? am i doing it a disservice by making it a stroker?
 
I race a stock stroke 340
I have been gathering parts to build my stroker.
I am using a 360 instead of a 340 for that reason
They are getting harder to find.
Atleast around here.
Thats my 2 cents.
 
I guess the question i was asking is... Is the 340 a rare engine, getting harder to come by? am i doing it a disservice by making it a stroker?

Who cares unless you're doing an all numbers matching resto, etc. It's not like you can't un-stroke it anway...and nobody will know from the outside. Well, except that it will be faster than a 340 :p
 
340's are worth more than any other LA sb because of the short production run and reputation.

If that block belonged to one of my Demons, it's worth more to me than any other 340 block... :)

If you don't know or can't find the original car, it's just another 340. Want a torquey SOB, put a stroker crank in it. High winder, run the 340 crank.

I would not use a 727 behind it unless it's a wicked big HP engine.
 
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