360 swap manifolds ?s

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bblock383

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Ok so I'm doing a 360 swap in my 66 and I'm worried about the flow of the 273 manifold on the drivers side. My situation here is I've got a 360 manifold on the passenger side and a 273 manifold on the drivers side. I'm worried about the differences in flow being so different between left and right cylinder banks causing issues. Is this a founded issue to worry over or not? I cant imagine it not having some sort of impact. Would it be better to have matching manifolds even though they flow less rather than one manifold flow better than the other? Your next question is about power steering and yes I do have factory power steering so I know it kills my options. I've heard conflicting issues on things like magnum manifolds as some people say they work(or should) and other reports that the magnums hit the manifolds to such a degree that it cant be fixed with a little grinding. Also read that C-body 360 manifolds may fit as well. I assume that 318 drivers side manifold flows better than 273 drivers side? I'm sure you've all seen the comparison Hotrod mag did with manifolds and headers on a 300hp 360 but no 273 manifolds done in the test to compare to.

Lemme know what you guys think. Thanks.
 
I would do the opposite. I would put the very best I could find on either side, even if the other side has to get the "worst."
 
find a driver side 340 log, 1/2 the price of a set and the passenger side you got is fine. And the C body 360 maifolds wont work IIRC.. I have never seen them in this application. Have you tried magnums? Flow pretty good for the price, like $50 bucks. If they are going to hit, itll be the steering column ad you can cut that back.
 
I would agree normally but with such a big difference and no other options to fix it outside of custom headers I'm not so sure. Now I know not EVERYONE to do this swap either already had manual steering or swapped to manual steering. What is everyone doing to fix this issue on the drivers side?
 
Pishta, Magnums as far as I know don't fit with power steering and are a tight fit even with manual it seems. Where can I get magnums for 50 bucks?
 
this is the bad boy you want, or if you get lucky, find its 68-71 big brother with the larger outlet (or just grind it out) turbodart68 had 'em for sale earlier
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Pishta, I looked into those before buying my 273 manifold and from the research I did that manifold goes right into the power steering box so the consensus was the 273 was the only thing that would fit since it curved back and not down into the box.
 
same place I got mine, from a member...OK, I digress: power steering is out.
Pick and pull on half price days, plenty of trucks with the magnum logs, easy pickins, look for the 92/93 model years with casting that ends with a 6617/6618, them's the large 2.125 early ones. Vans too, but they are a PITA to get out. hack saw is faster than trying to unbolt the headpipe flanges.
 
I only had 1 P/S 65 and it had 273 logs, my 68 340 motord 65 I had in high school had manual steering and 68 logs. sorry I couldnt guarantee the P/S setup. Ditch it ;-)
 
There is a pair in the for sale section but don't end in those numbers. When you say power steering is out, is that a suggestion to swap it for manual or what? Is keeping the 273 manifold on that side going to affect that cylinder bank or affect tuning or anything adverse outside of hp drop from poor flow?
 
doug 371 said:
ive tried the 340 manifold with power steering...doesn't fit
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Was it a 60s 340 driver or a 71 and up 340 driver. There's quite a bit of difference!!

Treblig
 

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Treblig said:
Was it a 60s 340 driver or a 71 and up 340 driver. There's quite a bit of difference!!

Treblig
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Treblig, will either of those fit my application? Unless you know something I don't, neither manifold will fit with power steering. The 340 exits right into the steering box apparently.



Doug 371, what made it not fit? What did you end up using instead?
 
bblock383 said:
Any other ideas anyone?
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I know that some FABO members have used the large hole Dakota manifolds by machining the manifolds on the head surface to give you extra clearance on the steering box and the steering shaft/column/joint. If you do a search you'll find multiple posts of members who have used larger (newer) manifolds on an early A. You'll have to spend a little money and do a little work.

Treblig
 
Listen to Treblig. Send him a PM. Get him on the phone. He modifies these manifolds for better flow and knows which ones fit. He will fix you up with something that fits and flows good.
 
Treblig said:
I know that some FABO members have used the large hole Dakota manifolds by machining the manifolds on the head surface to give you extra clearance on the steering box and the steering shaft/column/joint. If you do a search you'll find multiple posts of members who have used larger (newer) manifolds on an early A. You'll have to spend a little money and do a little work.

Treblig
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So your saying take material off the flange so it sits closer to the head/block? Was this on a power steering car?
 
bblock383 said:
So your saying take material off the flange so it sits closer to the head/block? Was this on a power steering car?
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Yes to your first question. "Don't know" to your second question. I sell (and machine) many of these manifolds and I know that the Dakota/360 Magnum manifolds will fit in an early A but I can't say for certain if they fit with power steering. Hopefully someone will chime in on that question?? Did you do a search?? Many other members have installed the newer manifolds into early A bodies.
I haven't advertised my manifolds in many, many months because I get too many orders. So I lay low!!

treblig
 

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Treblig said:
Yes to your first question. "Don't know" to your second question. I sell (and machine) many of these manifolds and I know that the Dakota/360 Magnum manifolds will fit in an early A but I can't say for certain if they fit with power steering. Hopefully someone will chime in on that question?? Did you do a search?? Many other members have installed the newer manifolds into early A bodies.
I haven't advertised my manifolds in many, many months because I get too many orders. So I lay low!!

treblig
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I did look at a few posts about this and it looks daunting to say the least and that's just making it fit a manual steering car. One member mentioned having to machine the flange down, putting shims under the motor mounts and cutting down steering collars and other such mods to the steering system inside the engine bay. I thought in the beginning that I could just port the 273 manifold and at least help it quite a bit as I'm sure ANY porting would help flow on that particular manifold but good grief the casting is so thin around the ports that I cant see porting it without getting to close to breaking through or making it too thin which would at the least lead to cracks. I noticed your sending out manifolds for research on this subject and Id really be interested in helping with that. I live in the southwest of Missouri which I think would get me within the 1000 miles your conditions state.
 
bblock383 said:
Those are the ones I mentioned to you in a previous post. They don't carry the casting number you recommended though so I assume they are the small hole manifolds?
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Yes, those are the small hole manifolds. Mopar made manifolds for magnum engines for many years but only certain manifoldS in certain years had the very large hole. These large hole manifolds aren't quite as large as the 340 but after I "machine" them they are as large or larger than the 340 making them the only other cast manifold that flows anywhere close to the big 340 manifold.

TREBLIG
 
Treblig said:
Yes, those are the small hole manifolds. Mopar made manifolds for magnum engines for many years but only certain manifoldS in certain years had the very large hole. These large hole manifolds aren't quite as large as the 340 but after I "machine" them they are as large or larger than the 340 making them the only other cast manifold that flows anywhere close to the big 340 manifold.

TREBLIG
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Do you know how much can be hogged out of the 273 manifold? Doesn't seem like much if any at all but I need to use it until I can figure somethin else out with these other manifolds. So id like to just do the best I can with what I have for right now. I know some people have talked about extrude honing the manifold but that seems like a expensive band aid and not a real solution. If I was running a 273 it would be more viable but I don't think there will ever be enough hogging of that manifold to get it anywhere near the stock 360 manifolds.
 
bblock383 said:
Do you know how much can be hogged out of the 273 manifold? Doesn't seem like much if any at all but I need to use it until I can figure somethin else out with these other manifolds. So id like to just do the best I can with what I have for right now. I know some people have talked about extrude honing the manifold but that seems like a expensive band aid and not a real solution. If I was running a 273 it would be more viable but I don't think there will ever be enough hogging of that manifold to get it anywhere near the stock 360 manifolds.
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If your lucky you might get another 1/8" (total) because the older manifolds weren't made very thick. But even then it might break!! Those old manifolds were only 1 5/8" exit hole, well at least that's what my factory 318 manifolds were. The 273 manifolds might even be smaller. The only reason I can get away with machining the magnum manifolds is that they are extremely thick. Extrude honing is not only expensive but it wouldn't help you much anyway.
Just remember that if you do go with the manifolds you have you'll have to pay twice if you switch them later when you get them hooked up at the muffler shop!!

Wishing you luck!!!

Treblig
 
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