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Discussion Starter #1
hi
I already did this optimization :
http://img.overpic.net/images/9/9/2/x992vvgi1ou904pe8lf5.jpg

but There is still a problem and i marked them

previously optimization is i removed the wall of the 1-3 canal and 2-4 ...

now when installing the carb for 1-2 barrel have a big problem and this is fuel encounter with its edge And create disorder but 3-4 haven't any problem !!!

now my opinion is :
remove these edge like this manifold :
http://img.overpic.net/images/9/q/v/x9qvkd8gy10s4p61vn8.jpg


What is your opinion ?
 

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Discussion Starter #2
what is the goal. If you are going to run a 1 barrel or two barrel carb it will be the biggest restriction in the intake track. Why not runa four barrel carb. They are more effeicent in many cases. They are also easy to adjust for best fuel managment.

The problems with the intakes is not the size of the runners or the things blocking them off its the turns the air makes going from the carb to the intake port in the head. That is why taller single plain intakes flow so much better.

The performer rpm intake from edlbrock has the best of both worlds but is not made for a single barrel carb but a two barrel will work with adapter plate. It will also require more hood clearence as its alot taller than stock.

Porting an intake is just like porting heads smooth all areas and round all corners as best you can. Anything that is sharp or angled needs to be smoothed out.
this is exactly and cleared my carb is 4 bbl
I do not want to buy a new manifold and my goal is optimize this factory manifold not any thing just this

now this edge is troublemaker and i will remove this


but center wall stay there and not removed
 

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. Since you already removed part of what is under the carburetor, might as well remove it all down to the plenum floors and run it like a single plane open plenum intake... you'll need to go 2 - 3 jet sizes larger in the secondaries if the carb. was previously tuned for the divided intake...


 

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Discussion Starter #4
. Since you already removed part of what is under the carburetor, might as well remove it all down to the plenum floors and run it like a single plane open plenum intake... you'll need to go 2 - 3 jet sizes larger in the secondaries if the carb. was previously tuned for the divided intake...
this intake is bad for low rpm ... this is good for 5000~8500 rpm

my usage is street every day usage in traffic and road and every where this intake very bad for my usage but dual plane manifold is good and nice for this using ...

but factory design have Factory building problems and when use the holley carb with adapter this problem Is larger than before !!!
because those edge stop the fuel delivery in normal and without disorder mode .

sample :

http://img.overpic.net/images/z/v/o/xzvonqj07c6xez76kmw.jpg

http://img.overpic.net/images/c/h/3/xch3jtnuxrszj9n093rk.jpg
 

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my usage is street every day usage in traffic and road and every where this intake very bad for my usage but dual plane manifold is good and nice for this using ...

but factory design have Factory building problems and when use the holley carb with adapter this problem Is larger than before !!!

. The factory intake was fine when using a spreadbore Q-Jet carb., but you changed the design yourself by using an open adapter and a squarebore Holley carb... you could have used a spreadbore Holley carb...


. Dual plane intakes aren't good for lower RPMs torque because they are 'dual plane', but because the dual plane design allows for LONGER intake runners... if you finish removing the divider, you will still have the longer runners... plus you will have better fuel/air distribution inside the intake manifold than with your current half cut down, half divided plenum setup...


. The stock intake manifold with the BEST low RPMs torque is the SINGLE plane TPI intake... best aftermarket intake for low/mid RPMs torque is the SINGLE plane SuperRam...
 

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Discussion Starter #6
. The factory intake was fine when using a spreadbore Q-Jet carb., but you changed the design yourself by using an open adapter and a squarebore Holley carb... you could have used a spreadbore Holley carb...


. Dual plane intakes aren't good for lower RPMs torque because they are 'dual plane', but because the dual plane design allows for LONGER intake runners... if you finish removing the divider, you will still have the longer runners... plus you will have better fuel/air distribution inside the intake manifold than with your current half cut down, half divided plenum setup...


. The stock intake manifold with the BEST low RPMs torque is the SINGLE plane TPI intake... best aftermarket intake for low/mid RPMs torque is the SINGLE plane SuperRam...
single plane design for high rpms and race engine not street and low rpm and high torque ...

the dual plane manifold good to use stock factory camshaft and low rpms but if u change the camshaft to a high duration and lift then u must be change the manifold to single plane
i have a book ( engine hotrroding - for the strip & the street - GM Ford Crysler ) this book say single plane have very bad low rpms and very good in high rpms but if u use a factory profile for camshaft best of the best manifold for u is dual plane because the dual plane are better air flow for low rpms and give higher torque and hp than single plane manifold in low rpms and single plane have low range cfm mean is in lower rpms air folw is slow and in this time have very disorder but 5000 to 8500 rpms air flow is very fast and all cylinders full and reach fuel
 

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you're on the right track to cut your stock one smooth. I would leave the divider in place since you have the adapter for single plane intake. It will give a little gap in between the sides of the intake and allow a little more flow.

. He has rear half of his plenum divided now and front half undivided which is what is causing his original complaint of uneven fuel/air distribution to the cylinders... plus the usual incorrect firing order of a SBC is causing air flow damaging turbulence in the semi-divided plenum... and fuel/air reversion from bouncing off the flat top of the remaining divider... making for a tuning nightmare... best to cut all the divider out now and let it work like an open plenum... we know those work... he still has the longer runners, which is the main benefit of a dual plane design, plus will have the increased flow of an open, more balanced plenum with all the divider gone...
.
 

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Do you know what that port does?
Do you have headers?
Will you ever run this motor below 10 degrees celsius (50 degrees farenheit)?
 

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Discussion Starter #11
Do you know what that port does?
Do you have headers?
Will you ever run this motor below 10 degrees celsius (50 degrees farenheit)?
I know something about this port like this port use for startup in winter ! just for this mode is this true ?
yeah i have a tall headers with 2.5" collector .
i'm living in iran and in my city winter temperature -25 in max and in normal about -5 ~ +5 but in fall is 0 to 15

now can i chock this port ?!
my goal is cool fuel and cool air coming to intake manifold and mix in the cool temp going to engine for better burning and beter volume efficiency and better fuel mileage ...
 

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THat port heats up the carb plenum. A heat riser valve on one exhaust manifold closes and the hot exhaust crosses thru the port and out the other manifold.
With headers you have no valve so you can block or leave it open. It won't make any difference. You'll just have a rough running motor until the intake warms up totally when the temp drops.
When you put new intake gaskets on, just cover the hole with a thin piece of stainless sheet metal. Some intake gaskets come with block off plates already installed.
FWIW you don't want really cool fuel and air. If it's too cool the fuel vapour reverts back to liquid fuel and the raw fuel puddles in the plenum. You won't have much vapour going to the chamber and it will run lean and misfire.
Cooler fuel/air will give you more power in hot temps but make your motor run like crap when the temp gets below 5-10C.
 

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Discussion Starter #14 (Edited)
THat port heats up the carb plenum. A heat riser valve on one exhaust manifold closes and the hot exhaust crosses thru the port and out the other manifold.
With headers you have no valve so you can block or leave it open. It won't make any difference. You'll just have a rough running motor until the intake warms up totally when the temp drops.
When you put new intake gaskets on, just cover the hole with a thin piece of stainless sheet metal. Some intake gaskets come with block off plates already installed.
FWIW you don't want really cool fuel and air. If it's too cool the fuel vapour reverts back to liquid fuel and the raw fuel puddles in the plenum. You won't have much vapour going to the chamber and it will run lean and misfire.
Cooler fuel/air will give you more power in hot temps but make your motor run like crap when the temp gets below 5-10C.
So no need to close this port ...
one question : why this intake manifold havent this port :
http://static.summitracing.com/global/images/prod/large/edl-7516.jpg
and this
http://static.summitracing.com/global/images/prod/xlarge/EDL-2601_xl.jpg

this is good to use this operating rpm range : 1,500-6,500 and secondary 1500-5500 !!!
but havent those port !
and high rpm manifolds havent this port like these :
http://static.summitracing.com/global/images/prod/large/edl-2814_w.jpg
http://static.summitracing.com/global/images/prod/xlarge/EDL-2825_HX_xl.jpg
 

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So no need to close this port ...
one question : why this intake manifold havent this port :
http://static.summitracing.com/global/images/prod/large/edl-7516.jpg
and this
http://static.summitracing.com/global/images/prod/xlarge/EDL-2601_xl.jpg

this is good to use this operating rpm range : 1,500-6,500 and secondary 1500-5500 !!!
but havent those port !
and high rpm manifolds havent this port like these :
http://static.summitracing.com/global/images/prod/large/edl-2814_w.jpg
http://static.summitracing.com/global/images/prod/xlarge/EDL-2825_HX_xl.jpg
Those are all air-gap intakes. Designed to keep the fuel vapor cool for max power. Just like you want to do. Just what you want if you're at the strip, wide open.
Your stock intake had a crossover port to help in the everyday/anyday hot or cold weather of your stock motor.
THose air gap intakes work great on the drag strip but can be fun to tune for everyday driving.
 

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Discussion Starter #17
Those are all air-gap intakes. Designed to keep the fuel vapor cool for max power. Just like you want to do. Just what you want if you're at the strip, wide open.
Your stock intake had a crossover port to help in the everyday/anyday hot or cold weather of your stock motor.
THose air gap intakes work great on the drag strip but can be fun to tune for everyday driving.
In anyway , this port must remain open for every day usage with gm manifold if i closed this then my engine just good for high temp like 15 to up C
is this true ?
 

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Open or closed, it makes no difference in your set up because you have headers. You have no valve on one exhaust to divert the hot gases thru there. Just remember that when the temp drops, your intake will stay cold for awhile until your motor fully warms up. Hot air rises. The heat for your intake will come from the lifter valley area. It will take longer to heat the intake. Not a problem if you're aware of it.
I've run headers in a cold climate for 50 years. Come cooler weather I always watch and listen for the tell tale signs of a cold intake.
 

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Discussion Starter #19
Just remember that when the temp drops, your intake will stay cold for awhile until your motor fully warms up. Hot air rises. The heat for your intake will come from the lifter valley area. It will take longer to heat the intake. Not a problem if you're aware of it.
in ur opinion what hotter oil in lifter valley area ( About 150~200 Degrees C) or exhaust gas ( About 2500 Degrees C ) ?
 
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