High flow exhaust Manifolds?

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swingingdart

swingingdart

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Does anybody make high flow exhaust manifolds for a bodies? I have headers, but am getting tired of the clearance issues I am having with them. I've smacked high spots in the road twice now and one pipe is almost collapsed. I'd love to go back to manifolds, but not the crappy flow!
Any help is appreciated! Thanks!
 
Chrysler did. Big block? Small block? Slant six? Briggs and Stratton? It helps if we know what you have.
 
67-69 340 manifolds are the best flowing. You can find them here through a wanted thread. You didn't mention what year or model but it doesn't matter much. Most manifolds fit most applications.
 
swingingdart said:
Does anybody make high flow exhaust manifolds for a bodies? I have headers, but am getting tired of the clearance issues I am having with them. I've smacked high spots in the road twice now and one pipe is almost collapsed. I'd love to go back to manifolds, but not the crappy flow!
Any help is appreciated! Thanks!
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You can’t have your cake and eat it too. Headers = high flow but clearance issues. Manifolds = less flow but no clearance issues.

Which do you prefer? High flow or no clearance issues?

It’s impossible to have manifolds without crappy flow (relative to headers) so don’t even state that.
 
Ask @Treblig if Magnums will fit, and look for the early 92-93 big mouth '617-8' castings.
53006617(driver's side)
53006618(passenger's side)
 
swingingdart said:
I just thought about this!
SORRY FOLKS! 1972 Small block, LA 318.
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yes the late 67-70/early 71 manifolds, then they changed in mid 71 to-74 ish which are still good, just not known as being as good as the earlier ones. I may have a passenger side one I might part with.

tti headers are known for better fitment too.
 
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H22A4 said:
It’s impossible to have manifolds without crappy flow (relative to headers) so don’t even state that.
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If it were only available again.....
1309-mopar-max-wedge.jpg
 
I would talk to @Treblig first and see what he says. I tagged him so he'll come sniffin around. lol
 
I can’t remember what the company’s name is, but there is a company in the Northwest, Seattle I think, that is making the 68-71 high performance 340 manifolds now. They are an exact copy of those. I, almost went with them, but was able to find a good stock set. Blast them, weld on ear on one of them, and finish coating them. Look as good as new.

114F37EC-13DC-42D4-85A8-90506AAD3205.jpeg


BBEDB23E-6AFA-4030-A234-CC7D3EDD5AFF.jpeg
 
Yep 68-71 340 hi po manifolds. From what I understand these flow about as good as shortie headers. They are pricey nowadays and originals are in limited supply. As hemisedan stated theres repops of them out there if casting numbers and originality dont interest you. I dont believe the repops come with a heat riser flap or the holes drilled for one. The bosses are cast in for a heat riser however.
 
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moparmat2000 said:
Yep 68-71 340 hi po manifolds. From what I understand these flow about as good as shortie headers. They are pricey nowadays and originaks are in limited supply. As hemisedan stated theres repops of them out there if casting numbers and originality dont interest you. I dont believe the repops come with a heat riser flap or the holes drilled for one. The bosses are cast in for a heat riser however.
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Yeah, I dont really care if they are original. It's a 318 so it wouldnt be original anyway! Okay, from what everybody has said I'll be on the look out for some hi po exhaust manifolds, I appreciate everybody's help! It's awesome being part of fabo where everyone is willing to lend some advice!
 
swingingdart said:
Does anybody make high flow exhaust manifolds for a bodies? I have headers, but am getting tired of the clearance issues I am having with them. I've smacked high spots in the road twice now and one pipe is almost collapsed. I'd love to go back to manifolds, but not the crappy flow!
Any help is appreciated! Thanks!
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Original 318 manifolds will work just fine. Delete the flapper valve, ceramic coat them inside and outside, be done forever.

Header/manifold dyno test
 
If your running a performer RPM you wont have a heat riser in the manifold and wont need the heat riser flapper.
 
Are 360 manifolds bigger than 318?

Either HP or not...
 
IIRC Year One has the 340 clones @ $750, AAR clones and casting numbers but fit and function as A as well. For $750, you can get originals with the heat riser and have $300 to spare, just search around.
 
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wonder how bad these flowed? Marine app...probably didnt 'flow' at all, but just dumped

exhaust-cm-318-360-end-cat.jpg
 
toolmanmike said:
yes 273/318 are the small port and 340/360 are large (larger)
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I know that's true of the intake manifolds (mostly) but are you sure about that on the exhaust manifolds? That's one I've never heard. Not that means a damn thing. lol
 
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