Adjustable idle air

[Pav8427]

New guy here. Gotta say thanks to all the great info both here and in the book.
Has the subject of an adjustable idle air ever been pondered?
My situation. I have offered to help a retired gentleman with getting his 66
GTO running better. Plan is to do up a late model quad and add a HEI.
I know some of the specs. But not all. At first I will drop the HEI in and get the timing curve
Up to snuff so that is ruled out. Then map the vacuum situation and the get with Cliff for
a kit and parts.
I am sure it comes with experience that one could build a quad, install and have it spot
on.
Just a thought. But if I had the recipe down and found I needed some/more
idle air, It would be nice to not have to pull carb off/apart2-3-4 times to
open idle air. I know that is the price you pay sometimes. But 2-3-4
times could get spendy with gaskets,possible breakage, warpage.
Been there done that.
We do have a product we use at the shop a lot that could work.
Heck it could even possible used as a tool for the more experienced guys out there.
Will take some pics. Any thoughts??
Thanks in advance.
Doug

[Frank400]

   Can you explain what that tool is ?  at the shop ?  what shop ?  Do you have a carb on hand that you plan to use ?  If so, what number ?

[Pav8427]

To clarify. Idle air bypass is what my quiz was about. Since it is a 'controlled vacuum leak', I was wondering if you could add a adjustable idle bypass to a quad.  Think idle mixture screw. Either by modifying a existing un-used manifold vacuum port or via new passages.
We design and build custom machines where I work. Some of our systems use various kinds of air controls on them. One of the things we use is called a flow control muffler. They are really just a needle and seat with a small thumb wheel on it. And either plastic or sintered brass muffler to quiet out flowing air. If it was added when rebuilding the carb and you come up short on idle bypass air, all you would have to do is 'crack' this valve open to get some more. If designed right you could set the carb up with some to begin with and if you come up with to much, you could turn it down.

The use of such a set up might be usefull to those who do more carbs than the average guy.
Thought crossed my mind that it could possibly help when some swap carbs around more than most or it could maybe help with tuning for altitude.

[Pav8427]

Yes I do have a carb. 17058253. 403 Olds. Just in the tear down/clean up/ planning stage.  Not in a hurry yet.  Supposed to get 4-8 inches of snow tonight. 1-2 Saturday and another 4-8 Sat night. When the warm weather hits I will finish it up and install.

[Frank400]

I see.  Much like some Carter AFB (or AVS ?) which have an idle air screw in the front. 

[Pav8427]

I realize there are best practice proven ways to make our quads work. Just thinkin outside the box. Over time if someone didnt do that once and awhile we may all still be runnin six strombergson on a log manifold on our 265's. Or in more modern times, that 454 quad should make my 305 run 11's and I wont have to use NOS.  Just wonder if it had been thought of. Tried. Would it work in theory. Too much work for results. Blah. Blah. Blah.

Thanks.

[omaha]

Let's not forget the air cooled bugs with the solex. Pict - 34 I believe. ALL THE air went through the adjustable air valve. I think  it would be fairly  easy to do. Especially. If the air did not need to go through the carb itself. I'm thinking a vacuum port near the base of the carb would  work. You  would need a source of filtered air [tap into the air cleaner would work, then a valve of some sort which would go into the intake just below the carb]. I would think it should work.

[Pav8427]

If you were retaining hot air choke could you open up vacuum port to obtain some/more bypass air?
Even if converting to electric, could you leave port open and add adjustable idle air bypass to choke housing? Technicaly you could add more bypass without removing carb.

[qjetsrule]

there are many ways to incorporate an adjustable idle air bypass, of course now that adds another adjusting screw. so now there are 4 screws to dial in the idle. this might confuse the average mechanic especially if an idle issue is caused by something else. I personally would like to have adjustable bypass air. Holley did it a little differently on some carbs, fixed idle fuel restriction and adjustable bypass air using the mixture screws.

[Pav8427]

Heres a mock up on a not so pretty carb. My thoughts would be that you set up the carb with some bypass. Like .06-.08, convert to electric choke and leave vacuum port open(maybe have to open up some. Add this valve and you should be able to add more bypass just by cracking it open. These are made by SMC and are less than 5.00 online. If someone is interested in trying these, there are a few different styles. They make meter out, meter in, and needle valve(air flow both ways). Meter in or needle valve style is what you would want to use. I have to check with my air control guy and see if meter in style will allow the small amount of vacuum needed. This one has 1/8 NPT, but you can get them from #10 all the way up to big. (1/2NPT)

[Pav8427]

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