Modification of the 4.1 4 barrel intake

jimski

In over my head
Apr 26, 2008
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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:
Just curious, if i send u some heads to do up for me what would be the damage.
 

charlief1

RIP Charlie!
Sep 20, 2007
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Just curious, if i send u some heads to do up for me what would be the damage.
It really depends on what you want to do to them Jim. A standard clean up of the bowls is around $200 (Teardrop shaped guides and removal of extra casting in the bowl with mild polishing) and if you want to go whole hog it gets expensive. I really work a set of heads hard if you want them hogged out but it takes a lot of work to do it so it costs a lot more. What castings do you have?
 

charlief1

RIP Charlie!
Sep 20, 2007
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what about the holley crossbore a double pumper q-jet style
I think a double pumper would be over kill. A vac secondary Holley spread bore would be fine though.:smile:

Hey, very nice work there! Very impressive!
Thanks. Wait until you see what I do to my heads. Last set I could put the exhaust valve into the bowl from the port side so this set should be better.:eek: :biggrin:
 

charlief1

RIP Charlie!
Sep 20, 2007
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charlie, where you get that intake??? looks good.
It's the factory 4.1 liter 4 barrel intake. You can pick them up cheap enough if you look around and they work great. The last one I did is in Norway right now.:eek: I didn't do all the work so I cut him a deal on it. Tor is very happy and I'm waiting for him to get the car back together. The only other mod you can do is add a one inch spacer to increase velocity. Makes charging the cylinders easier and add torque to the bottom.:biggrin:
 

charlief1

RIP Charlie!
Sep 20, 2007
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will parts for a 4.1 work on a 3.8? what about the intake:confused:
The 3.0(early), 3.2, 3.8, and 4.1 all have the same configuration as far as the heads. The intake will fit without any problems. The only issue you may have is if you have a set of 79.5-78 low port heads. I'll post some pics later of the ones I have here so you can get a better idea. There's a huge difference between teh two of them.
 

chaparral

New Member
Nov 20, 2009
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where are you located steve? You can do a lot with the 4.1 intake as well. Look for a thread on doing modifications to the 4.1 intake and see what you really can do to it to improve the performances of it.:biggrin:
although this looks to be very helpful, im confused as to what advantange i would be gaining by doing this, thing is i didnt understand what you are doing here and why. I guess i should say and dont have a problem admitting, i think your porting something but not sure i guess what i mean is do i have to do all that just to put a four barrel on my 3,8 or can you buy it the way you need it.

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.
 

WarWagon

Caustic Cacophony
Mar 10, 2007
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Fairmont WV
Chaparral: Charlie is increasing the flow of a stock 4.1 intake manifold, he is just cleaning it up making all the turns and corners smooth and getting a straighter shot at the intake ports in the cylinder head. All of that work Charlie is doing is not necessary to bolt a stock 4.1 intake manifold on either a 3.8, 4.1 V6. But all that work He did do will now outflow and be lighter than a stock 4.1 intake manifold.
 

chaparral

New Member
Nov 20, 2009
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chaparral: Charlie is increasing the flow of a stock 4.1 intake manifold, he is just cleaning it up making all the turns and corners smooth and getting a straighter shot at the intake ports in the cylinder head. All of that work charlie is doing is not necessary to bolt a stock 4.1 intake manifold on either a 3.8, 4.1 v6. But all that work he did do will now outflow and be lighter than a stock 4.1 intake manifold.
is it a delicate process for a back yardian to conquer im pretty mechanically inclined but seems like a lot or maybe it is the tools or lack of the tools maybe. Just trying to get something out of something where maybe i should just re work it or replace it, need tons of other parts as well do you have any available

hood rear deck lid fender flares interior etc.
 

1chance

Active Member
Aug 8, 2007
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Im thinking of putting a bonnet on a Q-jet for a carb turbo setup! Why not cut the metal out the middle, will it mess up something?
 

WarWagon

Caustic Cacophony
Mar 10, 2007
1,890
64
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Fairmont WV
That divider in the middle of the carb pad in the intake manifold is mirroring a dual plane intake. In reality the stock buick 4.1 4bbl intake manifold is a single plane design. If you split the intake down the middle of the carb pad and compare the port runners they are the same BUT the carb pad does have the divider like a dual plane intake manifold only it is not solid, so it lets the two opposing port runners mix. Single plane.

The Q-jet is very finicky and varying being used for blow thru. It can be done but it requires lots of mods and tuning and you CANNOT seal the accel pump so it only good for up to 12psi.
I built and used one for blowthru and got it to work OK but it leaked BAD at 10psi.
 

chaparral

New Member
Nov 20, 2009
73
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0
chaparral: Charlie is increasing the flow of a stock 4.1 intake manifold, he is just cleaning it up making all the turns and corners smooth and getting a straighter shot at the intake ports in the cylinder head. All of that work charlie is doing is not necessary to bolt a stock 4.1 intake manifold on either a 3.8, 4.1 v6. But all that work he did do will now outflow and be lighter than a stock 4.1 intake manifold.
that divider in the middle of the carb pad in the intake manifold is mirroring a dual plane intake. In reality the stock buick 4.1 4bbl intake manifold is a single plane design. If you split the intake down the middle of the carb pad and compare the port runners they are the same but the carb pad does have the divider like a dual plane intake manifold only it is not solid, so it lets the two opposing port runners mix. Single plane.

The q-jet is very finicky and varying being used for blow thru. It can be done but it requires lots of mods and tuning and you cannot seal the accel pump so it only good for up to 12psi.
I built and used one for blowthru and got it to work ok but it leaked bad at 10psi.
wow that went right over head and clear out in left field, maybe im out of my league, hell i didnt realize the little 3,8 v6 is so complicated, i was just wanting to thro a alum. Intake on there with aftermarket carb. Like eldebrock or someting get a little more pep out of stock moto, till i can figure out what to do with this project. I just got it planning on fliping it and making a buck but i got attached to it, and threw some money at it and its actually pretty decent ride. Took me back to my school day i always wanted one of those buick grand nationals and i guess im having a little fun cloaning one. Lol anyone have parts i should cahnge my name to (need parts) instead of chaparal. By the way chaparral is my boat manufactuer my nemisis is boating like i said i thought to get this car and flip it, it flip me. Lol
 
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