340 - Stock Exhaust Manifolds or Headers

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Whether they hang low or stick up through the hood, headers make more power. Period.
 
Sorry I'm east of the Mississippi. So quickest on the east side.
 
Hmmmm.
Maybe I could be converted after seeing the TTI shorties - I"m old school was unaware of these even though they may have been around for decades, sorry.
I thought all E body headers dragged on the ground.
Question please - Can/do these headers seal well against the head?
 
Like RRR says, headers make power period. and I've heard it said that the more overlap your cam has the more significant the increase.
Same goes for the LSA. the tighter ones like a 108, make more power up top, than a wider 114 say, but this goes back to the overlap.
If it has less than 20* (off the advertised numbers),Ima thinking the HO 340 manifolds will be fine.....
If your cam has more than 40* of overlap it will respond well to headers.
If it has over 60* overlap, it would be just plain silly to not install headers.

There used to be an HR magazine test that took a stock Hi-compression 70s 340 and dyno'd it with the stock HO manifolds and compared it to long-tube headers. I forget the results but i think it was pushing 10% power increase with headers. The factory 340 bumpstick boasts 44* overlap.
I never heard anybody ever brag on their 340 being torquey with that cam, even with the advertised 10.5Scr.... so... IMO anything you can do to pick up the bottom end torque is a plus..... and so for me, headers would be mandatory
 
Depends on what you mean by "stock manifolds".
If they are "NOT" 340 HiPo manifolds, don't waste your time.
Hey Johnny, These are what I meant by "stock exhaust manifolds". I think they are stock...I just bought the engine (340 with X heads). Do you think that they would fit in a 69 Cuda? Thanks

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Hey Johnny, These are what I meant by "stock exhaust manifolds". I think they are stock...I just bought the engine (340 with X heads). Do you think that they would fit in a 69 Cuda? Thanks

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Hallelujah !!!! Now we are getting somewhere. :)
Those are a set of HiPo 340 manifolds, and as mentioned, will bolt right up with no issue. In regards to manifolds vs headers, it depends on what your plans are with the car. If a bolt on, painless,dependable, exhaust with decent performance is what you are after, go with the manifolds.
Accurate exhaust has a complete exhaust system for your car, from the manifolds back. TTi should as well.
 
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Putting on headers and getting them to seal is not rocket science.
I run hookers on my 340 dart they fit well and I used percy's soft aluminum gaskets and they don't leak. Don't let headers out smart and get the best of you
 
Hey Johnny, These are what I meant by "stock exhaust manifolds". I think they are stock...I just bought the engine (340 with X heads). Do you think that they would fit in a 69 Cuda? Thanks

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Yep. What AbodyJoe and JD posted.

Attaching to the heads:
If the machined surfaces are straight - no gasket is used or needed.
Use studs on the ends. Install into the heads with a little pipe sealant.
There are heavy conical washers available. The washers are helpful. Not used on the middle two bolts.
Some venders sell long nuts - these are nuts aren't needed.

Attaching to the headpipes:
Gasket used is in between the sizes most parts stores carry. I like the gasket Accurate Ltd sells for this a little better than TTI's as they have a metal ring.
 
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Been using some ceramic coated dynomax headers. Once tore open lower hanging header on a manhole that was sticking out!! At the time had 14" rallyes. Took car to my local muffler shop and they patched up the tear @ bottom of pipes. To this day still have these on my dart sport. No leaks after I went with Percys aluminum gaskets. Now also have 15" rallyes all around no more scrapping issues.
 
In my opinion, if you have a 340 with a slightly hotter than stock cam, you will not be happy with non 68-70 manifolds. The 68-70 ones flow a lot better than others. In my opinion there is little sense in putting lower flowing manifolds on a modified (even if only slightly modified) 340; which is a performance engine.
 
I finally purchased a numbers matching 1972 Dodge Demon 340 4 speed assembled on 10/25/1971 with a rebuilt 340 engine to 69/70 Dodge Dart specs. The only thing I plan
to add is a set of TTI Headers. Since the 340 is basically stock with six pack cam 280 D 474 lift. Should I follow TTI s advice and run the 1 5/8 primary to 1 3/4 secondary
headers or can I install the 1 7/8 inch headers being that the Demon is a standard.
 
First, where I'm coming from.....
I have three cars with headers on them, and three more sets hanging on the wall.
If you have the stock manifolds, for your car I would not bother with headers.(but if you do, the step headers are the better choice)
My current thinking is that if you're not planning on racing, or are not building a car with 450 hp, I wouldn't bother with headers.
All three of mine with headers have 500 or more horsepower, and run elevens or better.
My guess: the TTI's might be worth 20 hp over the stockers, is that worth a $grand to you?
 
First, where I'm coming from.....
I have three cars with headers on them, and three more sets hanging on the wall.
If you have the stock manifolds, for your car I would not bother with headers.(but if you do, the step headers are the better choice)
My current thinking is that if you're not planning on racing, or are not building a car with 450 hp, I wouldn't bother with headers.
All three of mine with headers have 500 or more horsepower, and run elevens or better.
My guess: the TTI's might be worth 20 hp over the stockers, is that worth a $grand to you?

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Headers are always better. The engine breathes better. Longer individual tubes on each of the exhaust ports makes even a stock engine a better engine.
I put a Header on a 2.4 4 cylinder and it woke that 93 hard body truck up. If you really want more power out of a stock or barely above stock engine
shorten your exhaust system.This will cause less restriction and more Torque and torque= horsepower. I've had A-bodies with exhaust coming out in front of the rear tires and that 340 Duster ran like a raped ape out of hell. Keep the original exhaust manifolds and store them away but run headers and shorten exhaust system and you will make power and can be budget minded at the same time.
 
I had 340 manifolds on my on my mild magnum build, went with the cheap summit headers, and remflex gaskets thread locker on bolts. I’ll never go back to manifolds the amount of torque I gained and h.p was worth it!
 
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