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I've heard the Magnum Exhaust manifolds flow pretty good, does anyone have any experiance with these compared to a pre-magnum manifold on a truck?
 

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But do headers designed for the new Magnum engins bolt up to out LA motors? Will shorty headers work, I've heard that they dump out at the rear and have fit problems on our RC's

Cheers

Chris
 

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v737d said:
But do headers designed for the new Magnum engins bolt up to out LA motors? Will shorty headers work, I've heard that they dump out at the rear and have fit problems on our RC's

Cheers

Chris
A header no matter what motor it's designed for will out flow any exhaust manifold.
As for the question your asking im not sure of exactly what it is you want to know, if your asking about using a shorty header designed for mag motor in a truck a mag motor came factory with then i think your shorty header isn't going to work in a earlier RC or P/U
 

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I believe they would clear but not by much. why would you want to use a shorty header on an older truck though? Full length headers are better.
 

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Ahh, yes full length are better but make so many other things a pain in the butt. I don't need or desire huge horsepower, so I was keeping the shorty option open. Shorts, downpipe, x-over, cat, pipe, muffler, tail pipe, 4" led lighted exhaust tip......ok I'm jpking about the last one!!

Cheers

Chris
 

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v737d said:
Ahh, yes full length are better but make so many other things a pain in the butt.
Cheers

Chris
What other things? ?
 
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So does anyone know if Magnum and LA manifolds are interchangeable?
BTW the ports are larger in the 92' and early 93' magnum exhaust manifolds. Good for an extra 10hp. I read this in an issue of Mopar Muscle. It shows the difference.
 

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James_Craig said:
So does anyone know if Magnum and LA manifolds are interchangeable?
BTW the ports are larger in the 92' and early 93' magnum exhaust manifolds. Good for an extra 10hp. I read this in an issue of Mopar Muscle. It shows the difference.
Interchangeable with what?, i don't think the rear pointing at the frame dumping exhaust manifolds are going to work on a RC or early P/U, they might but why in the world would you try if your going to remove the factory exhaust manifold then the only thing you should go to is a header after that, i don't believe your gonna take your exhaust and toss it and gain 10hp with a set of mag manifolds
 

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According to the Mopar Performance A engine book (PN: P4876826), the Magnum manifolds will physically bolt on to any earlier LA engine. The performance gains will be roughly equal to the 1968-70 340 HP manifold. Mopar did flow both sets of manifolds and found the 68-70 rt side flowed slightly better than the Magnum, so in a perfect world the 68-70 340 HP manifold for the rt side and a Magnum for the lt side. Mopar did not quote a specific number for the performance gain.

I sit the side of the fence that PREFERS a decent factory cast iron manifold. They are quieter, more durable, less expensive (for equal quality) and always fit. In the end my truck will be fortunate to hit 300 hp (I had a prior career in a dynomometer facility as an operator so this is not a magically made up number). I would not feel any real benefit of a tubular header, unless you consider lessend starter life, joyous oil change experiences, less durability (more apt to break, corrode and dent) and greater chance of leaks a benefit.

 

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Sure they will bolt to the head, but they exit differently then the older exhausts and even the 40 hp exhausts exit differently than the mag manifolds.
As for the starter issues i have always upgraded to headers on every vehicle i have owned except for my Jeep GC, i have had headers that wrapped around starters like a snake, in my life i have changed 2 starters, 1 in a Dart 340 and 2nd in my Jeep, the only 2 starters ever to have a problem and the Jeep doesn't have headers.
As for the leaking situation i find it all depends on the materials used and the person killing down the bolts and bending up header flanges and using crappy collectors.
Chance of denting them damn good chance in a A body and B body when lowered for road racing and driven on the street, in a truck not unless you're silly with a hammer.
Oil changes in a truck with headers are a simple feat, much easier then sb in an A body with 2" underchassis headers and for that matter the simple fix there is canton oil spin on block adapter, 2 braided lines, 4 an fittings, and a peterson adapter and then even a oil change on that isn't a problem.
Corrosion is the only problem a header has
 

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I know the manifolds will interchange, but the magnum has a rear exhaust dumb while the LA manifolds has a center dump. Why not just use headers? My old LA headers bolted right onto my magnum motor. Starter issues? The only issues you would have would be the old full size starters with the header tube running right behind it. Just upgrade to a high torque starter. $75 at autozone with a lifetime warranty. I put mine in in 98 and still have the same one.
 

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those manifolds are different from the truck ones. The jeeps also had 10 hp less then the truck engines because of the exhaust. so keep that in mind.
 

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I doubt you will find, feel any benefit of those log style jeep manifolds,
 

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Evildriver-3 said:
I doubt you will find, feel any benefit of those log style jeep manifolds,
The stock manifolds have 1-7/8" outlets while the jeep ones have 2-1/8" outlets. I should see a benifit. My other choice was a set of hi-po 340 manifolds, but they are running in the 200-400 range while I picked up the jeep ones for $30....I don't want headers on this car.
 

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suimmit has a set of street rod headers for around $170
the part # is PTE-H8205 small chrysler 1 5/8" o.d. raw 169.95
coated 279.95
they should be almost a stock location dump on a 2wd. couple that to a set of high flow cats h-pipe and a set of 40 series flows with 3" tips and you should get a decent h.p. increase
 

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Gosh, don't know if you got your question answered or not.
Just swapped a 360 magnum into my 85 RC. The magnum manifolds are very different but are a direct bolt up on a LA small block. They are larger and they exit in the rear instead of the center. There is no heat riser and they are much larger and more free flowing.
The ONLY problem I had with this swap relating to the manifolds was the passenger side manifold interfered with the tranny dipstick tube. I had to unbolt the tube and move it so the manifold would fit.
I just wired it down to the tranny so it couldn't wiggle out and leak.
 
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