Modification of the 4.1 4 barrel intake

charlief1

RIP Charlie!
Sep 20, 2007
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I've done a few of these intakes over the years and when I show the pics I was asked to post a how to do it so here goes. This will be a long post so if you have any comments I'll ask that you wait until you see the final results. About 35 pics in all so it should explain all you need to know. The tools I'll be using are standard die grinders but the bits are really course so the aluminum won't clog up in the bit as much. The WD-40 is to spray on the bits occasionally to help keep them from building up and it does work to some degree. You can do this with an electric die grinder as well but since I work in a shop and I had a half day off I figured the boss could pay the electric bill. If you look at the die grinders I have put a regulator on each one to control rpm a little easier. If you're using an electric one you can use a router controler to control the rpm. Most of the time you will have the high rpm to make for a smoother cut but when using the flapper wheel go slower so you can control it better.
The first thing you will need to do is to mark the maximum cut for the top. A little dyechem is great but if you don't have it a magic marker will work just as well. Make a line from the edge of the front and back barrels and use a strait edge.
 

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charlief1

RIP Charlie!
Sep 20, 2007
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Once the marks are made then out comes the mighty sawzall. If you've never used one they can get away from you fast. Once you cut the top out then it's time to start using the die grinders. I start on one side and work around the edge to the back.
 

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charlief1

RIP Charlie!
Sep 20, 2007
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You can see the EGR passage in the center but don't worry about it. If you really want to do it cut the center in the front out for a little more flow but you really don't need to. If I had access to a TIG I'd probibly weld some metal over it to reduce the passage but it still won't make to much of a difference.
Now that you have the two sides and back pretty much done you get to cut out the front. I used a flashlight so you can see the metal in the front of the intake. This is just a shell and unlike the back and once you get rid of it you see the next suprise. I highlighted it with yellow marker so you can see it better. It's a boss for the front bolts. One on either side and it's a big lump to get rid of. GM could've done much better in the intake and you can see the insides much better.
 

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charlief1

RIP Charlie!
Sep 20, 2007
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These next pics are from the head side. One side is unported and the next is showing how much you open it up for better flow. Now you can see how much you're opening it up and a side by side comparison of the back.
 

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charlief1

RIP Charlie!
Sep 20, 2007
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Finished product after blasting and then polishing most of the runners. Yes it makes a difference and you will see no difference on the bottom end but the top will be much easier. This allows you to have a better flowing intake and still stay 50 state legal if you have to. Hope yall enjoy the info and I hope you decide you like my work.
 

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charlief1

RIP Charlie!
Sep 20, 2007
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Last one and an extra. The die grinder kit I'm showing is one I got from wally world on clearance. I have 8 air and 5 different electric ones for this kind of work so If I find a good deal I grab it. See if your local store has the kit. I got it for $30 and I usually pay about 3 times that for one of these kits.
 

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Finallall

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Oct 6, 2008
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Very cool post man. Awesome work! I have a few questions for you.

Aproximately how long does it take you to do an intake? Begining to end.
Did you use any extentions to get into the runners to port inside?
Did you have to do any carb adjustmeints after you did the porting?
What would you say is the performance increase before porting and after?

Thanks.
 

charlief1

RIP Charlie!
Sep 20, 2007
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3,682
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No Where But TEXAS!!!
Very cool post man. Awesome work! I have a few questions for you.

Aproximately how long does it take you to do an intake? Begining to end.
Did you use any extentions to get into the runners to port inside?
Did you have to do any carb adjustmeints after you did the porting?
What would you say is the performance increase before porting and after?

Thanks.
Overall time is about 20 hours. No extentions but with the angle head grinder you can get into the intake a little better. I have a Fordom design grinder and with the pencil head on it you can get into some of the narrow sections better. There's a good "from the seat of the pants" if you know what I mean. Add a 1" hiker and it will pull like crazy. The air/fuel velocity is increased so the cylinder charging is better but the hiker isn't nessisary but it does help.
 

turbo3.8monza

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Oct 24, 2006
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San Antonio, TEXAS
I like the quadrajet for stock or mild set up but for pretty modified set up I prefer a holley, gas mileage goes to crap but it so much easier to get the full potential of the motor I'm not saying it can't be achieved with a quadrajet it takes a lot more tweaking. on the factory 4.1 intake I just ported between the primaries more to clear the throttle blades and used an edelbrock mounting with the center set of holes
 

charlief1

RIP Charlie!
Sep 20, 2007
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With the small primarys you get better velocity and if you tune it right you should get better gas mileage. It also helps on vacume and idle issues. We have to use them in the dirt cars and never found an issue. One of the best tricks I learned by accident was to use an early m4 off a chevy instead of the 4m design. The earlier one responds better for track time but the later works better for street droving.
 

turbo3.8monza

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Oct 24, 2006
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I'll definatly agree with you about the gas mileage, throttle response, and street manners, there is nothing better for a cruiser. my dad has 79 corvette l82 thats all stock other than headers and true dual exhaust with cheapo turbo muffles and even with almost 200k miles it still gets close to 18 mpg with 3.73 and super t10 tranny and has great throttle response to the point its hard to drive in the wet. actually I think the carb has never been rebuilt, if it has been it was a LONG time ago at least 15 years back when I was a little turd
 

charlief1

RIP Charlie!
Sep 20, 2007
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3,682
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No Where But TEXAS!!!
There is always something interesting coming out of charlies's garage.
Thanks Jim.:smile: Just wait until I get some more money in my account and I finish the headers I've been working on. Aj and a few others know what I'm up to but right now I don't wat to let to much out about them. If it works the way the math says it will all fo us will benifit from them. Faster and better boost will be the nice thing about them.:biggrin: