The exhaust manifold shoot out I saw the 340 manifolds increased power 7 hp over stocker 318 manifolds
Exhaust Manifolds
- Thread starter Dan the man
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Swinger 340
Well-Known Member
What's that with stock pipes. 2.5% don't sound like much. Headers will give you around 10% more HP, but that is also a larger pipe to correspond with the header tubes and chamber. I installed 318 manifolds on my 340 when I first installed it in my van. I was not impressed with the motor change at first. Next week I installed headers, not 340 manifolds, What a big difference. I just read your comment again and maybe on a 318, but not a 340, sorry for the add-on.
Dan the man
Well-Known Member
Sounds like the best thing for a 318 is 360 manifolds and for the 360 there's nothing other than headers. I wish I had the magazine that they built a 318 using only factory parts,except for the pistons. I remember they used 360 manifolds from a Dakota but I don't remember if it was a A body or not. Looks like headers is the best way to go and I think that Doug's headers probably will fit the best.
If you search here, all that has been discussed. All the numbers and any modifications to do. The only reason for the Jeep manifolds is because the right manifold exit is close to 2 1/2" . 67-70 340 manifolds aren't a issue (if I have my dates right)
If it's gonna be stock and you're ok with leaving 20-40 ft lbs in the table, pretty much everywhere across the power range, then any old stock manifolds will do. Yeah the 340 mans probably make a bit more than the others.
The cheap hedman headers are total garbage. The cheap summit branded headers are actually pretty nice with thick 3/8 flanges. Get those.
Don't waste time with any kind of shorty headers they are barely better than manifolds.
Headers help regardless of displacement.
I could never figure out why. I put a set of Mickey Thompson Try Y's on my 73 Challenger. 340 car. I didn't do any carb tuning after the install but I slowed down a few hundredths. It went faster with stock manifolds and full exhaust.
340six
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Can walk 10 feet and see 3 from where I am at and an X Block motor
I've never installed tri-y headers so no experience there.
Every time I've installed headers it has always, always made a significant improvement.
Dan the man
Well-Known Member
Jeep manifolds? I don't think that Jeep manifolds will fit a sbm. And the only Jeep that I know of that has a mopar V/8 is the 4.7 and from what I've read those won't work on a sbm either. If I'm wrong here and I very well could be, what year Jeep manifolds fit a sbm? And do both manifolds fit? The whole idea of this post is what if any truck exhaust manifolds or car for that matter flow the best, this idea was for a budget exhaust system that would help over all performance and not break the bank account. I've seen Doug's headers on a dart sport but they are like $900. If I can get the duster that I'm going to look at it already has headers, the other one doesn't have headers and I was just looking for some better flowing exhaust manifolds. What would be good mufflers to run?
Well pardon me for saying Jeep. Many Magnum manifolds will fit. Some may work. Others not. You need to do some reading. Like I said. There are a lot of threads in the exhaust forum about the subject.
My 98 Jeep Grand Cherokee came with a 5.9l, 5.2l was a common engine for them
Dan the man
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I didn't mean to sound disrespectful here.
Dan the man
Well-Known Member
My bThanks. I'm just about ready to put Dan on Ignore.
Dan the man
Well-Known Member
Damn..the Red X is gone...
@Dan the man I'll put it straight out there: It's gonna be some kinda street cruiser, right? Little bit of pep to do a burnout, good acceleration, make some noise, have fun? Right?
Well guess what: headers are a big part of this. Like I said: get the cheap summit branded headers. Forget about messing with manifolds. You're leaving a lot of torque and power on the table if you stick with manifolds.
Honestly headers are the first thing I've always installed.
It's real simple.
1. Get a car, with the biggest engine that's in good shape you can find.
2. Treat the engine to good parts (headers, intake, carb, camshaft).
3. Go burn rubber till it gets boring.
4. Repeat steps 2&3.
Well guess what: headers are a big part of this. Like I said: get the cheap summit branded headers. Forget about messing with manifolds. You're leaving a lot of torque and power on the table if you stick with manifolds.
Honestly headers are the first thing I've always installed.
It's real simple.
1. Get a car, with the biggest engine that's in good shape you can find.
2. Treat the engine to good parts (headers, intake, carb, camshaft).
3. Go burn rubber till it gets boring.
4. Repeat steps 2&3.
Yep. It's a shame TBH. The red x definitely has it's place.
340six
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But then he can't Troll.
Step one would be get a car! Period...
Getting a car would be a good 1st step, but I'm no 318 hater but don't get the obsession with building a low rpm mild 318. You seem to want strong 2000-4000 rpm torque (power) not a 318 most strong suit.
OldmanRick
Well-Known Member
One of my buds in the 70's bought a 70' Duster 318, bone stock internals w/3spd and 3.23's. With a LD4b, 600 Holley, regulation headers and 2.5 exhaust installed went 15.00 at 91mph on multiple occasions. That's about 200 net hp. I doubt a 72/74, non hp, 340/360 style manifold would have slowed it down much.
The reason i bring this up is, would you be happy with that level of performance?
If no and you'd want to build on that later, then save the coin and buy the the good coated headers up front. You'll be glad you did later.
The reason i bring this up is, would you be happy with that level of performance?
If no and you'd want to build on that later, then save the coin and buy the the good coated headers up front. You'll be glad you did later.
kart70
Member
I guess I will carry the pro manifold torch here. There are two things manifolds have over headers. Simplicity of installation/maintenance and ground clearance.
The installation/maintenance is pretty clear. There is a lot more room into the engine compartment for one large pipe on each side of the engine than four smaller pipes. That makes access to your starter, oil filter, clutch linkage, steering, brakes, and suspension so much easier.
Ground clearance may or may not be an issue with modern headers. Be careful about what you are shopping for. All I know is that I bought the cheapest set of headers for my Duster back in the late 90s and they lasted for less than a year. They caught on speed bumps, trailer transitions, and even regular bumps. Hard to brag about performance when your bottom two tubes on each header are smashed flat. I'm told the expensive headers like TTI and Doug's have solved that issue. All I can say is that if your headers go under the steering linkage, be prepared for low clearance issues.
In short, my opinion is this. If you want your car to be a no fuss, go anywhere type of cruiser/ daily driver, I'd consider manifolds. Not necessarily 340 manifolds. They are not worth the money IMO. If you're looking for performance, go expensive headers. You'll probably spend as much money and get more performance. Of course, if you want to sacrifice a bit of convenience for performance, headers are a great way to go. Just be aware what you are sacrificing no matter what the choice you make.
The installation/maintenance is pretty clear. There is a lot more room into the engine compartment for one large pipe on each side of the engine than four smaller pipes. That makes access to your starter, oil filter, clutch linkage, steering, brakes, and suspension so much easier.
Ground clearance may or may not be an issue with modern headers. Be careful about what you are shopping for. All I know is that I bought the cheapest set of headers for my Duster back in the late 90s and they lasted for less than a year. They caught on speed bumps, trailer transitions, and even regular bumps. Hard to brag about performance when your bottom two tubes on each header are smashed flat. I'm told the expensive headers like TTI and Doug's have solved that issue. All I can say is that if your headers go under the steering linkage, be prepared for low clearance issues.
In short, my opinion is this. If you want your car to be a no fuss, go anywhere type of cruiser/ daily driver, I'd consider manifolds. Not necessarily 340 manifolds. They are not worth the money IMO. If you're looking for performance, go expensive headers. You'll probably spend as much money and get more performance. Of course, if you want to sacrifice a bit of convenience for performance, headers are a great way to go. Just be aware what you are sacrificing no matter what the choice you make.
Hate to get sucked in, but I can also say, I like manifolds. As a matter of fact, I only put headers on one side of the 64 Barracuda and pulled it off. Had other cars with headers and hated them. They are at the dump with the side pipes, traction bars, Holley carbs, and everything else I did not like. I run the best manifolds for the car I have, Jet Hot coat them inside and out for the thermal barrier, order original style exhaust am done. 66 formula S with early A manifolds, 68 383 Barracuda with original manifolds, 67 Barracuda with 340 exhaust manifolds. Stockish pipe sizes, stockish mufflers, clamps, hangers, and tips. Everything fits perfect, bolt it all on and go. Quiet, cool under the hood, last forever. I can drive the car all day and the High performance engines still sound great from the back. I make enough horsepower that I can give up 10-20 hp no problem.
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