340 Manifold questions

[Confusedcuda]

I just bought a 1971 340, it has 9 to 1 comp. trw pistons a med purple cam and it cam with a Edelbrock LD4B manifold. I hear this manifold has smaller ports on it. Do I need to change manifolds or can I stick with this one. Also what would be a good carb? Thanks

 

[Johnny Dart]

I would go with a manifold that matches the 340 ports.I like the Edelbrock Performer rpm or better yet the performer air-gap.The Weiand Stealth is another very good manifold.

For a carb,the Holley 670 Street Avenger would be hard to beat.This carb is good for 300-400 hp.

 

[AdamR]

If it runs good and its a street car run it. Why spend cash you dont have to. You probably would see a big gain switching and may loose low end torque.

 

[crackedback]

If you feel the need, port match the manifold to the heads... It's basically the same manifold as an LD340 only with smaller 318 ports.

If you swapped it to an RPM or air gap, I bet you would NOT notice a significant change in performance. BTDT... LOL

 

[rumblefish360]

Depends on the 340 build. The LD4B is more so ment for the 318 while the 340 and 360 should have the LD340. Intakes pictured below show there differences. There not the same but more suited for the respected engine sizes. The LD340 is modified for racing.

 

[73DartSport]

From what I know and what I have been told you are not going to see much of a difference if you make the swap... if you are planning to do any racing at all the swap may be worth it because even small gains can mean a lot for ETs in a specific class, but if its only for the street I don't think you will make it into the ranges to see those gains often enough to spend the extra money. Only other reason I would change it is if you're just a purist and HAVE to have all 340 parts on your engine.

 

[dodge freak]

I have a old Hot Rod mag, which they claim they got 9 hp more by swapping a LD 340 from a LD4B intake. They were happy but I would not be, to much work and $$$ for just a 9hp gain.

 

[64dartwagon]

I have a old Hot Rod mag, which they claim they got 9 hp more by swapping a LD 340 from a LD4B intake. They were happy but I would not be, to much work and $$$ for just a 9hp gain.

That kind of gain in a newer car costs around $1,000. And you better hope it's legal at that.

 

[73DartSport]

WHAT!?!?! You're crazy to spend $1000 for a 9horse gain in a new car...most new cars will take a high flow air cleaner that will add between 10 and 15 horses and in most applications this add-on only costs 300-400 dollars at top end. And, yes , that's for some of the newer high performance vehicles. So to spend $1000 for a 9horse gain is crazy... If you're payin that... you're payin too much.

 

[rumblefish360]

I have a old Hot Rod mag, which they claim they got 9 hp more by swapping a LD 340 from a LD4B intake. They were happy but I would not be, to much work and $$$ for just a 9hp gain.

That is more so just to show the difference between the 2 intakes and show what the correct intake will do for you. If you were to purchase an intake, and not have one to start with, like a 2bbl. to 4bbl. swap, that article would point you in the right direction.

Having the LD4B intake allready, I wouldn't swap out intakes unless your looking to make some good street power over just a simple upgrade by compare.

They, the mag, was more so happy at the gain, not the amount, by the right intake on the right engine.

 

[64dartwagon]

WHAT!?!?! You're crazy to spend $1000 for a 9horse gain in a new car...most new cars will take a high flow air cleaner that will add between 10 and 15 horses and in most applications this add-on only costs 300-400 dollars at top end. And, yes , that's for some of the newer high performance vehicles. So to spend $1000 for a 9horse gain is crazy... If you're payin that... you're payin too much.

I was refering to the stickered winged cars vaguely. I figure they spend $800 on stickers and lights to advertise the part and $200-400 on the actual part.