Headers for J body

J Body General Discussion

  1. Jaketrae123

    Jaketrae123 New Member

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    I'm installing a new exhaust setup in my Imperial, and was wondering what headers would fit, with little to no persuasion, shorty, mid or long tubes are fine with me. Thanks
     
  2. MiradaMegacab

    MiradaMegacab Well-Known Member

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    TTI has some nice headers.
    I run Hooker 5115, they might be too much for your application, depending on your mods.
    Both of these headers go above the steering linkage, helping with ground clearance.
    Check out the listed applications, perhaps you can find some at a swap meet, you just have to know the interchange models.
    Screenshot_20170425-084735.png t Screenshot_20170425-084903.png n
     
  3. 80mirada

    80mirada Well-Known Member

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    Dougs 453 fit above the steering.
     
  4. CrAzYMoPaRGuY

    CrAzYMoPaRGuY Member

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    I just installed Hooker Super Comps, 5115. They fit pretty good but needed to be tweaked for the steering box and the passenger side apron. Shorty filter fits without the 90 degree adapter and end studs on both heads can remain and be used.
     
  5. 89.Fifth

    89.Fifth Well-Known Member

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    Wait, will these also fit an M? or no?
     
  6. Aspen500

    Aspen500 Well-Known Member

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    If you can afford them, the Schumacher headers for both small and big block are excellent and fit with no problems at all, even with an RB in an F-body. They are pricey but you get what you pay for.

    The small block ones are for automatic trans only and there are a couple other mandatory items like a 90* oil filter adapter and a mini-starter.
    http://engine-swaps.com/Pages/ProductsType/SB_Headers.html#head1
     
  7. 6thGenImperial

    6thGenImperial Well-Known Member

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    Been considering this myself. Guess I'm counter-culture on this one. I gotta look, but I was thinking on slipping in some '92 vintage Magnum manifolds. Gotta see if they'd fit. I'm thinking they will.
     
  8. 89.Fifth

    89.Fifth Well-Known Member

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    Some hit the firewall and some don't. I haven't been able to test it out myself but there is supposed to be a magic combination out there of van, jeep, and truck headers that works.
     
  9. BudW

    BudW Moderator Staff Member

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    The Magnum exhaust manifolds come in two different designs.
    The design for pickups, vans, Dakotas and Durango’s – the rear exit and firewall will want to occupy the same space and are not recommended.
    318 Manifold l 97-03 PU.jpg
    Left
    318 Manifold R 98-03 PU.jpg
    Right
    Note: all pictures used on this post, were swiped from eBay.

    The Jeep Grand Cherokee, the exhaust exit is between the two rear-most cylinders – and will fit our cars.
    318 Manifold L 96-98 GC.jpg
    Left
    I could not find a picture of Right side – but it is pretty much a flip side of Left manifold. There are venders selling the Right side on eBay – but have no pictures are up.

    Depending on what year your FMJ was born on, this picture may vary slightly - but the overall shape and exit is the same for Left side.
    318 Manifold L 76-80.jpg
    The right side is not critical and most all small block exhaust manifolds will fit - except for the pickup/van/Durango/Dakota magnums (top two pictures).

    I can't be of any help with headers - for I will not use them.

    There are several magazines who has flow tested Mopar small block exhaust manifolds, and the best flowing is the ’68-71 340 – but those manifolds are not easy to find, nor cheap when you do find some. They are being re-popped – if anyone is interested and also have money to burn.

    This 340 Right side manifold might be one of the best ever exhaust manifolds ever made, possibly.
    340 Manifold pr 68-71.JPG
    The Left side goes up and over the steering gear.
    It fits FMJ cars and I have seen it on a few of our members cars – but looks out of place (in my opinion).
    I have a pair of the above manifolds in my garage and a strong likelihood of using the Right side, one day.
    The Left side - I have no plans on using and it is for sale (fairly cheap) if anyone is interested (casting number 2863553).

    The second best flowing small block are the above mentioned Magnums.
    The early (Magnum) years – the exhaust exit has a larger diameter hole. No mention in flow tests if this works better or not – but if I was going to look for Magnum exhaust manifolds – I would look for the early years. I left my laptop at home today – so don’t have my casting number data on hand to mention here.

    In May 2012, I purchased an Left '94 Grand Cherokee 318 manifold, casting number 53009477 for the incredible amount of $13.75 (which included freight) on eBay. This manifold has the 2-1/8" diameter exit.
    One of these days I'll install that as well as my Right 340 manifold onto my car . . .
    BudW
     
  10. 6thGenImperial

    6thGenImperial Well-Known Member

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    I read an article on the early vs later Magnums. The 2 1/8's were said to flow better than any available header at that time, and they agreed it was the best since the early 340 Magnum. I'm sure there's some header that would edge them out now, particularly at high rpm, but not by much in street trim. Mopar claimed the smaller 1 7/8's improved low rpm torque, but I seriously doubt that. More likely money-related. Always, ALWAYS count on the bean-counters to mess up a good thing. The quickest V8 RWD Mopar since the Lil Red Express was the '92 318 Mag Dakota-up to that time. Side-by-side, the equally equipped '93 (with smaller manifolds) was a over 2 tenths slower in the quarter. Later Dakota RT's (360 Mags) were flat out dogs by comparison.

    Interesting photo/info on the Jeep versions. I had heard there was some sort of different Magnum manny out there, but had never seen the difference. Hmmmm. Now I have something new to watch for at the U-pull it yard.
     
    Last edited: Apr 7, 2018
  11. BudW

    BudW Moderator Staff Member

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    I’ve heard that pictures are equal to 1,000 words. Well, it might be in some cases, I guess. In this case at least having a visual aid helps a person from purchasing something that won’t work for you.

    It is kinda odd to say it, but in this case: don’t get Dodge Magnum exhaust manifolds – get Jeep instead.

    My pull-a-part (not far from my home) gets in a lot of Grand Cherokee’s – but not looked under the hoods of ‘em. Maybe I need to . . .
    BudW

    BTW, the '68-71 340 manifolds exit is 2-1/4".
     
  12. Norse

    Norse Active Member

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    Finally jumping in on this thread as I start to collect parts.
    Bud W; I did some Ebay searching and found several "pre 96" left side Jeep Grand Cherokee manifolds and very few (2) right side from the 96-99's.
    Is the split in 95/96 where the bean counters messed with everything or can I do one of each?
    (I'm installing full dual exhaust w/x-pipe but the engine is staying stock with just the 650 Edelbrock 4-bbl)
    Also; any thoughts on picking up the factory heat sheilds/manifold bolts or going aftermarket?
    TIA
     
  13. Duke5A

    Duke5A Well-Known Member

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    155_0307_exh_dyno_z.jpg

    The above is from a dyno shootout from Hot Rod Magazine from like 2003. Factory manifolds (any of them) only start to become a restriction at 300 horse power. If you're not going into the internals of a smog era 318 motor you'll be nowhere near 300 HP with just bolt ons. Keep your factory manifolds and run duals off of those.
     
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  14. BudW

    BudW Moderator Staff Member

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    Once Chrysler went to throttle body injection in ’88 (pickups), they also stopped using the heat stove system. If you live in an area that doesn’t freeze (or get that cold that often), then the heat stove will not see any action.

    If you need (or want) an exhaust stove system – you might have to fabricate it yourself. It is very possible existing parts might fit (not tried – so can’t say).

    I've seen a bunch of Grand Cherokee exhaust manifolds in the Pull-a-Part by me and will start to get some (to sell). To be honest, I’m not sure what the difference is between the years is – but I suspect it might have to do with a drilled EGR boss (maybe) - or lack thereof.

    The magnum manifold design, with its taper down effect (if that is what you want to call it), I suspect helps with overall flow rate and low-end torque – but I have no way to prove it. There must be some reason for the odd (non-linear?) design.
    Mag L 94-03 Truck.jpg
    '94-03 pickup version.

    I have heard the first couple of years of Magnum exhaust manifold exit hole is larger than the later years – but not had enough in my hands to make comparisons.


    As far as mixing up manifolds – honesty, I don’t think it makes a huge difference: if manifolds are comparable.
    I have a pair of ’70 340 manifolds and a Left ’94 Grand Cherokee in my garage. I don’t like the Left 340 style manifold design, the way it goes over the steering gear (nothing wrong with it – but just don’t like it). My plan was to use the Grand Cherokee manifold on Left side and my 340 manifold on Right side – whenever I get around to that project.
    Having headers on one side of engine and a FMJ 318 log manifold other side - is not something I can recommend.

    Another thing to remember is the fuel injected engines (which includes Magnum) do not have a mechanical heat riser on (or under) right side exhaust manifold. In my case, my Right 340 manifold has had the heat riser removed and holes welded up by previous owner – and I’ve owned this set sense the early ‘80’s.

    With that said, I would venture to say that most of the 318’s our forum members own – the exhaust crossover passageway in the intake manifolds are already stopped/plugged up – so without intervention, an operative heat riser is not a high concern.
    BudW
     
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