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Discussion Starter · #1 ·
I know this isn't for my gasser but if it works out ok on my pickup we will build something similar for my '56 Chevy once we get to that point.

Norman and I have been considering building an intake manifold for my pickup for some time. The one the criteria is that it has to be something completely different but be fully functional. We started putting the plan into action this past week. Here are some pictures and thoughts as we have been coming up with our design. Any thoughts or critique is welcome. This is a driver and we want it to run rights.

We started with 1/4" intake flanges that a friend of ours had water jetted out in Colorado. The flanges are great and fit the intake ports on the heads perfectly. I had to open up the bolt holes for the flanges because of the angle the bolts go into the heads. I put a big block Chevy rocker arm ball under each bolt that will be welded down to the flanges. The ball will maintain the right angle for the bolt and give even pressure for torquing them down.



To tie the flanges together we have welded 1/2" X 1" mild steel as a border around the intake valley. The stainless steel that is laying across the valley as pictures will be removable. It will be bolted down onto the valley frame work. Unfortunately my battery died on my phone before I could get a picture of it. I will get one later and post it.

The main portion of the intake from the flanges up are going to be constructed out of stainless steel and tig welded. I started by cutting 2" diameter stainless tube into 6" lengths and then I worked one end of them in the vise to make them rectangular to fit the intake ports. The 2" diameter works out perfectly to make the shape for the intake ports. The stainless steel holds the shape much better than mild steel also so it wasn't much work to make them fit. The 6" length is just a starting point on the height into the plenum.



We tried mocking up several designs of plenums for the intake. The taller one in the back was our first shot at one but we realized right away that it would end up being way to tall for our application. The shorter one in front was our second shot at it but we determined that it looked too bulky and the intake runners looked to small and out of proportion.



I guess I haven't mentioned it yet in the post we are planning on running five Rochester two barrel carbs on the intake. We have been collecting the 250 cfm ones at every swap meet for a while so we have a good supply of them. Norm has an eight deuce manifold for his 392 hemi that he is using them on also. Here is a picture of the layout we are going to use. The air cleaners are on there only as an idea for now on what to use.



Our plan is to run on the center carb as the primary and have them all be setup so that they are fully controllable by progressive linkage. We will probably need to use restricter plates to keep the total cfm at about 850 but we will have to try it and see.

Our third attempt at making a plenum looks about right. The intake runners would be about three inches with it and the proportions look much better. The overall height will work out just about perfect also.






If any of you have any thoughts or see something we missed please speak up. We are in the planning stage and it's easy to adjust something now.

Keith
 

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Discussion Starter · #2 ·
After some consideration we decided to use a big base Rochester as the primary carb. Norm has collected a number of them also so I have several to choose from. I used the plasma cutter today to cut out a carb base plate for one. Here are some pictures of our progress today.







Keith
 

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Discussion Starter · #3 ·
Here are a few more pictures from today.





After taking a look at the carburetor stands we decided that we are going to shorten them at least an inch.







Keith
 

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Keith, this is a very interesting build, to say the least. My first question, is, are you planning on leaving the tubes exposed as much as possible ?
Also are you planning on raising the center carb, as in one picture it appears that way, and would look very cool ! !
 

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Discussion Starter · #5 ·
Steve,

There is going to be about three inches of the tubes exposed. That's all that I can afford to do for this intake. The over all height from the top of the block needs to stay at about thirteen inches. That's what's on my pickup now and I can't afford to go any higher. The windshield is only nine inches tall and I want to retain as much of my visibility as possible. It's a driver and I want it to be somewhat driver friendly. We most likely will leave the center one taller. The stand is the same height as the other four in the picture but the air cleaner is I little taller. I agree with you I think is looks better taller.

Keith
 

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Discussion Starter · #6 ·
We got a little more progress done this week. The runners are all welded in and the top is welded on along with the back of the plenum. We are working on making the pop off valve for the front of the plenum.





Keith
 

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Discussion Starter · #7 ·
We made more progress tonight. You can see in the picture the slot on the front of the manifold for the pop off. We got the four outside carb plates lined up and tacked into place. A few more hours of grinding and welding and it should be done.



Keith
 

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Nice work! Do you have any concerns with the volume and runners not at the lowest point of the intake? If fuel puddles or stands in the flat bottom it could make a big boom if you ever get a hiccup and it backfires. Might want the bottom to be peaked in the center, or the runners lower to avoid puddling.
 

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Discussion Starter · #10 ·
Hi Vall,

That was one of the things that I was concerned about and I'm not so sure that it won't cause some problems. If you look at the photo on the bottom front of the manifold you can see two bolts sticking out. There is a slot cut between them and we have made a plate that will be spring loaded to cover the hole. It should take care of any back firing through the carbs I hope.

Keith
 

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Hi Vall,

That was one of the things that I was concerned about and I'm not so sure that it won't cause some problems. If you look at the photo on the bottom front of the manifold you can see two bolts sticking out. There is a slot cut between them and we have made a plate that will be spring loaded to cover the hole. It should take care of any back firing through the carbs I hope.

Keith
Missed that! Should surely take care of any possible backfires! I've seen some guys retrofit blow off plates to the old shoe box Edelbrock tunnel rams also. They had a horrible problem with fuel puddling and catching fire internally!
 

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I think its awesome that you took on this intake from scratch. Im not a fuel specialist but I have experienced some carb issues with uneven flow and a out of balance vibration from uneven fuel over certain cylinders. So my question is this: would the front and back carbs directly over the intake runners feed fuel to front and back of the engine causing a wide open throttle or acceleration issue. overly rich you might say and inside cylinders would be lean? I was wondering if maybe the carb plates should be in between the first two and last two cylinders. I wonder if there is any intake and fuel experts out there to share an opinion on this. I find this real interesting. I think you did an great job putting that together and thanks for posting it for us to see.
Mario
 

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Great tech! I hope it works just because it's so cool. That linkeage is going to be a brain teaser. Can't wait.

I built an intake for an old sandrail that I had with a 2.8 Chevy v-6. I had a couple Del'Orto carbs (Italian Webers) from a Porsche that was wrecked and it looked cool and ran OK. Hard to get enough fuel to the engine. I can't find any pics! but that was in the 90's... :)

Mike
 

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Small plenums often create a lean/rich situation to cylinders. It looks like you've got enough plenum that it wont be a real issue, but a plug check once it's done will tell. Often it takes a good highway run at 70 mph or so and then shut down and check the plugs to see if they're getting even fuel distribution.
My Austin's Holley Pro Dominator seems to run richer on the rear cylinders than the front. I've got the carbs jetted to be rich enough to not lean out up front, although they're a little rich in the rear. I sometimes foul #7-8 cylinder plugs with a lot of idling.
 

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Discussion Starter · #16 ·
Ok, it's finished and ready to be bolted on. We are going to give it a shot today. We may only be able to get the center carburetor hooked up to test it. We have a local car show this weekend that we want to have it on for that. The four on the corners may just be bolted on. We will have to see. I haven't had time to rebuild them and kill the idle circuits in them yet.



Keith
 

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Looks awesome Keith. Great job.
Mario
 

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That is a great looking intake Keith. Fantastic job, I can see your inspriation on the bench behind the intake. Get a video of it running when you get it all set up. Way to go!!
 
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