318 exhaust manifolds on a 360

Mopar Exhaust Systems

  1. arh

    arh Well-Known Member

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    Getting tired of fighting the header on the drivers side on my freshly installed 360 in my 69 barracuda convertible. All kinds of clearance issues with steering box, suspension etc. nasty vibrations in the car. I have a really nice set of stock 318 casting# 2843953 and 2465719. Will they work on my 360 ? I also have a left side 340 casting # 3614395 can I use it with the 318 manifold on the right?

    Thanks,
    Adam
     
  2. 66340SEDAN

    66340SEDAN FABO Member #3649 FABO Gold Member

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    Yes, those 318 manifolds will work in your car on the 360. The 340 one would be better but I would run another 340-360 on the right side so they flow the same, try to find another to make a pair.
     
  3. arh

    arh Well-Known Member

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    Is there a big difference between running a pair of 318 verses a pair of 340 manifolds
     
  4. Cuprum-74

    Cuprum-74 Moparus Fanaticus

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    Yes there is a difference. There was an article I read awhile back comparing 318 & 340 exhaust manifolds to headers and such. I'll try to find that article again.
     
  5. 66340SEDAN

    66340SEDAN FABO Member #3649 FABO Gold Member

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    There is a slight power gain over 318 ones but not as much as most think.
     
  6. Cuprum-74

    Cuprum-74 Moparus Fanaticus

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  7. Woods74

    Woods74 Broke Senior

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    ^ Thanks, was just about to break out that old chestnut.
     
  8. arh

    arh Well-Known Member

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    Great article. Wish I would have read it before I bought the headers. I will be putting the stock manifolds on and stop fighting with the headers.

    Thanks,
    Adam
     
  9. crackedback

    crackedback FABO Gold Member FABO Gold Member

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    A stockish engine will show similar results to the test. More aggressive stuff, the increases from headers become greater. My 340 runs very different with headers compared to the 70 hp manifolds that got pulled off. Night and day difference.
     
  10. arh

    arh Well-Known Member

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    My motor is a pretty stock rebuild. 360 with j heads and a Hughes whiplash cam. Performer intake with a 650 carb. I think pretty close to the engine in the article with a bit more cam.
     
  11. 69B-Cuda

    69B-Cuda Well-Known Member

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    I had a 360 with J heads in my 69 Barracuda, I could never get the stock 69 318 manifolds to seal... the ports were too much bigger on the j heads than the manifolds...
    I ran it that way for a few years though choosing a bit of an exhaust leak over crappy headers... then I bought TTIs for it...
     
  12. Treblig

    Treblig Well-Known Member

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    I have a '69 Barracuda w/power steering. 318 with 302 casting heads. 318 manifolds don't seal well because the ports are much smaller, see pics!! I'm using a 340 driver's side manifold and a 92-93 Mag truck 360 manifold on the passenger's side. the large port 360 mag truck manifolds are cheap $40-$60 on ebay and the flow real good. The exit port on the 360 manifold is only 1/32" smaller than the exit port of the 340 manifold....for $50 that's a pretty cheap solution!!!!

    You can see the small 318 manifold gasket compared to the 360 gasket. I painted the 318 gasket blue so you can see how much of the 318 gasket falls inside the 360 gasket port. The 360 manifold almost swallows the 318 gasket and this is why you will have sealing issues. You can even see a little daylight at the bottom of the port (in the corners).

    Treblig
     

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  13. krazykuda

    krazykuda Well-Known Member FABO Gold Member How-To Section Editor

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    You could always get a carbide burr set and open up the exhaust manifold ports to match the heads.
     
    • Disagree Disagree x 1
    • Treblig

      Treblig Well-Known Member

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      The problem is with the bottom of the port. There just isn't enough material there to cut. The bottom of the 318 manifold doesn't have enough material to cover the 360 head's port.

      Treblig
       
    • krazykuda

      krazykuda Well-Known Member FABO Gold Member How-To Section Editor

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      I did it on a pair of manifolds that I put on a 74 charger with a 360. Get it as close as you can with what you have to work with.

      68 - 70 340 exhaust manifolds would be the best choice if you can get a set.
       
    • pishta

      pishta I know I'm right....

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      I say Magnums and if you get the xxx18 castings, they are 2.25 outlets instead of all the others at 2.00. They were used on 318 and 360 so the port size is compatible.
       
    • Treblig

      Treblig Well-Known Member

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      What did you ever end up using for exhaust in your 360 Barracuda???

      Treblig
       
    • arh

      arh Well-Known Member

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      i stuck with the poor fitting headers. had the exhaust shop heat and bend,dimple,releive where they had to. the car sounds great but disapointed with the power. i only have maybe 200 miles on it and when it gets a few more i will start fooling around with the carb and timing.
       
    • RustyRatRod

      RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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      Mike at MRL Performance did testing between HP and stock manifolds and found zero difference on the dyno as I remember. I am sure every combination is a little different.
       
    • Treblig

      Treblig Well-Known Member

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      I thought you said that you had a 340 driver's side manifold?? Why don't you use that.? A dimpled/dented header really cuts into your power. If you have a 340 manifold all you need is a 360 "special" manifold like the one I have in my 69 Barracuda. It fits perfect and there's plenty, and I mean plenty, of room for the down pipe. It kicks the exhaust out over and behind the oil filter. Don't get the 360 magnum manifold that I've seen other suggest and use. The mag truck (driver) 53006617 has the exit flange coming out real close to the floor/firewall and will introduce heat to the passenger compartment. The 360 manifolds I have exit in the middle of the large space on that side and come with an exit hole just short of 2 1/4" ( a hair over 2 3/16"). That's just about the same as the 340 manifold. No leaks, no "dragging on the ground", no retightening the header bolts and lots of room for your down pipe!!
      I'm planning on going into production on these and sell them to FABO members, like me, who hate the high price of headers, hate getting their pipes dented and scraped by the street, hate the difficult installation and don't forget those "lovable" header leaks. Anyway that why I figured all this out and will start producing these (slowly). You would be first in line, but if this turns out to be popular I'll sell to he who has the money!!
      If you're heavy into drag racing then you need headers but if you cruise the streets like me and you don't like choking down your engine then "This Bud's For You!"
      They come sand blasted and painted with High Heat Paint!!

      To make things even better, these should flow even more than the ones they tested on those magazine sites!!!!!!!!!!!
      Haven't started advertising yet because I wanted to build up a stockpile of them in case I get inundated....one can hope!!! LOL


      PS - I even included some pics of my car from underneath so you can see where they exit and how much room you have!!
      Treblig
       

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    • dart67

      dart67 FABO Gold Member FABO Gold Member

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      I would be interested, depending on the price
       
    • Treblig

      Treblig Well-Known Member

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      PM sent.

      Treblig
       
    • CUDACOX

      CUDACOX Well-Known Member

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      * Like farting through a straw! .
       
    • Treblig

      Treblig Well-Known Member

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      The regular 318 exhaust manifold is 1 7/8 ID on the exit hole (I'll post pics tomorrow). My manifolds are just short of 2 1/4" ID. So, would prefer to run 1 7/8" pipe all the way back to your rear bumpers OR 2 1/4" pipe??

      Treblig
       
    • RustyRatRod

      RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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      What's so special about that exhaust manifold that you caint share the castin number?
       
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