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Modifying Single barrel manifold to Two barrel?
https://slantsix.org/forum/viewtopic.php?t=37809		 Page 1 of 2
Author:  carpdar [ Thu Nov 05, 2009 9:12 am ]
Post subject:  Modifying Single barrel manifold to Two barrel?
I've noticed the super six setup going above the 200 dollar range lately and i was wondering if theres any major differences between the single and double barrel manifolds in relation to port size, runner length, or flow.

Other than the throttle/kick down linkage, it doesnt look like to big of a job to make a carb opening/bolt pattern template, match the manifold opening, and tap some studs into it.

I've seen it online, im just wondering if anyone on this fourm has has done this yet.
Author:  SlantSixDan [ Thu Nov 05, 2009 9:20 am ]
Post subject:  Re: Modifying Single barrel manifold to Two barrel?
Quote:
I've noticed the super six setup going above the 200 dollar range lately and i was wondering if theres any major differences between the single and double barrel manifolds in relation to port size, runner length, or flow.
Nope. All those parameters are identical.
Quote:
Other than the throttle/kick down linkage, it doesnt look like to big of a job to make a carb opening/bolt pattern template, match the manifold opening, and tap some studs into it.
If you have the tools and facilities, you certainly can do. And it gives you the option of putting together a parallel-mount 2bbl intake setup; see this post.
Author:  coconuteater64 [ Thu Nov 05, 2009 9:39 am ]
Post subject: 
I might be wrong, but I think Reed has done such a thing. I modded my intake to accept a large-bore Holley 2 bbl up from the standard super six 2 bbl. Not really rocket science if you scratch your head on paper first before touching any tools.

Just search for it, because I've seen somebody do it before.
Author:  carpdar [ Thu Nov 05, 2009 11:11 am ]
Post subject: 
Wow thats a great article dan! I've thought i've seen most of the slant fabrication/modding pages but thats a gem!

From what i understand my stock BBS is around 230cfm stock, and im looking in the 350cfm area with a secondary to help lower my highway mpg.

I might be getting an slant 6 from a 68 camper special (truck crankshaft :D) and would like to incorperate an erson cam perhaps in this build.

Any ideas on the best performaning (and economic) 2 barrel for this setup, since i can choose just about any carburetor bolt pattern?

thanks,

-Aaron
Author:  Charrlie_S [ Thu Nov 05, 2009 12:33 pm ]
Post subject: 
I have a factory 1 bbl manifold on my 66 Cuda. Modified it for a holley 500 cfm 2 bbl mounted sideways, and 6 nitrous fogger nozzels in the runners. I just machined the single barrel flange flat. Cut a piece of 3/8 thick steel plate to match the holley pattern. Spray welded the plate to the manifold, then bored the holes, into the manifold.
Author:  carpdar [ Thu Nov 05, 2009 12:48 pm ]
Post subject: 
What did you use to enlarge the opening? I guess the manifold is cast iron so using an drillpress to make holes and an air-grinder with carbide bits would be the easiest way..

I might be able to get ahold of some kinda router/lathe, or maybe take it to a cnc place here in kelowna..

What model of holley is that?
Author:  coconuteater64 [ Thu Nov 05, 2009 12:58 pm ]
Post subject: 
Quote:
What did you use to enlarge the opening? I guess the manifold is cast iron so using an drillpress to make holes and an air-grinder with carbide bits would be the easiest way..
I used a drill press to make a bunch of small holes, then smacked the metal with a hammer.The unwanted metal fell right out. Used a Dremel and stone to smooth it.
Author:  D-Ram 1596 [ Thu Nov 05, 2009 1:44 pm ]
Post subject: 
I would go with a machine shop or someone who has some skill with a mill (then again if I wasn't in college I would be a machinist :)). I say this because they can mill the entire top flat properly so you can weld/epoxy your adapter with less worries. Plus they can make the adapter plate right there that will fit perfectly to the manifold. It is more expensive, but worth it.
Author:  Reed [ Thu Nov 05, 2009 3:32 pm ]
Post subject: 
Yep. I took a cast iron one barrel intake, ground the mounting pad flat, used a BBD base gasket as a template, drilled a bunch of holes, whacked the unwanted parts out, and then used two piece of flat iron stock to build up a new mounting pad. THe intake eventually developed leaks since I used JB weld to secure the two barrel mounting pad to the manifold. If I were to do this again, I would weld the seams, notJB weld the seams. Otherwise, it worked great for a couple months until the gasoline ate up the JB weld.
Author:  carpdar [ Thu Nov 05, 2009 3:35 pm ]
Post subject: 
Well I'm going to college for Automotive Service Tech in 3 months so i cant spend money on professional services.. I'm thinking i should just buy a carb spacer and use it like a template and possibley use the spacer with it as well if i can tune my engine to take advantage of that.

I have acsess air tools, power tools, and a pretty healthy shop.. so I think i could improvise something :p

The Linkage might be a little tricky but as long as the carb is mounted in a way i can use the stock 'rotating' style throttle linkage assembly.

As far as which carb I'm going to use I am not decided.. Might adapt a 318 two barrel or get a bit more creative ^_^
Author:  Reed [ Thu Nov 05, 2009 3:54 pm ]
Post subject: 
The biggest problem you will face is the lack of space. The one barrel intake barely has enough area to mount a BBD, whether you put it perpendicular or parallel to the motor. A four barrel or even a larger Holley two barrel would be out of the question unless you were willing to cut and modify the sides of the "box" underneath the carb.
Author:  dodgeram86 [ Thu Nov 05, 2009 4:49 pm ]
Post subject: 
here's some pics carpdar, start to finish 4 hours and getting around 17 mpg city driving and 25 mpg highway on a stock six

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Author:  Charrlie_S [ Thu Nov 05, 2009 7:31 pm ]
Post subject: 
Quote:
. A four barrel or even a larger Holley two barrel would be out of the question unless you were willing to cut and modify the sides of the "box" underneath the carb.
4 bbl might be a problem, but there was no problem, using the big Holley 2bbl. The hardest part was makeing the flat area on the top of the manifold. I used a milling machine, which made it easy.
Author:  Reed [ Thu Nov 05, 2009 7:54 pm ]
Post subject: 
Did you mount the carb parallel or perpendicular? WHen I made my modified intake, I mounted the carb in the normal perpendicular manner. I ran into the boss for the inboard intake-to-exhaust mounting bolt and almost ran out of room on the outboard edge. I think you would have more room if you put the carb on parallel though.
Author:  wvenable [ Fri Nov 06, 2009 4:36 am ]
Post subject: 
Well, you could do all that modifing or you could just buy my cast iron super six intake! :D
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