Carb Tuning - Page 2 - Vintage Mustang Forums

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post #16 of 26 (permalink) Old 02-17-2017, 01:25 PM
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Quote:
Originally Posted by GT289 View Post
Four corner idle, substituting air bleeds, etc. are all things that are more
the bailiwick of someone tuning on a dyno or who has access to a wide
band A/F meter (like an Innovate) at the very least.
Without those things you're just guessing at fuel curve.
tHESE DAYS IT IS but BACK IN THE MID 60s UNTIL ABOUT 10 YEARS AGO NEVER USED an AF gage. Just read plugs, vacuum gauge , temp gauge, ETs, fuel mileage, throttle response, etc.
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post #17 of 26 (permalink) Old 02-17-2017, 03:18 PM
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Quote:
Originally Posted by GT289 View Post
Four corner idle, substituting air bleeds, etc. are all things that are more
the bailiwick of someone tuning on a dyno or who has access to a wide
band A/F meter (like an Innovate) at the very least.
Without those things you're just guessing at fuel curve.
Absolutely ! If I hadn't been relying on my AEM a/f gauge it would have taken days, not hours to get the right tune on my Paxton's and Weber.

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post #18 of 26 (permalink) Old 02-17-2017, 04:04 PM
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Quote:
Originally Posted by Claudemiro View Post
Well that isn't true. There is an idle circuit, a transition circuit, a main circuit, a power circuit and of course a choke circuit.That doesn't included the accelerator curcuit which piggy backs on the others. So, not as simple as you say.
You can word it anyway you want and try to be cute about it, but generally, Holley's are considered to be 2 circuit carbs. The Dominators are considered 3 circuits. So yes it is true.

Straight from Holley:

https://www.holley.com/products/fuel...ors/dominator/

1969 MaCh 1 - CHP 427w 10.8:1 comp
TFS 205cc 11R heads || Victor Jr. intake || 950 Holley HP carb || 110* 236/240 .573/.594 hyd roller cam || 1 3/4" ceramic coated headers || 3" exhaust, x-pipe || 14" 6 piston front and 13" 4 piston rear Wilwood brakes || T56 Magnum || SPEC 2+ hydraulic clutch || 9" Detroit Locker || 3.70 gears || MSD 6AL-2 || PST Aluminum DS || many more.

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post #19 of 26 (permalink) Old 02-17-2017, 08:11 PM
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Originally Posted by Claudemiro View Post
There's nothing cute about the facts. I presented the facts, not dreamland, just the facts.
And so did I. I'm not saying you were wrong in listing the different circuits within the two main circuits the carb operates with. But when I stated they were considered two circuit carbs (which they are - FACT - Holley refers to them as two circuit carbs), you oddly had no problem trying to discredit my post. There is no need for that, especially when the information I posted was fact and true to begin with. It makes no sense, you were making a point to just create an argument out of nothing.
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1969 MaCh 1 - CHP 427w 10.8:1 comp
TFS 205cc 11R heads || Victor Jr. intake || 950 Holley HP carb || 110* 236/240 .573/.594 hyd roller cam || 1 3/4" ceramic coated headers || 3" exhaust, x-pipe || 14" 6 piston front and 13" 4 piston rear Wilwood brakes || T56 Magnum || SPEC 2+ hydraulic clutch || 9" Detroit Locker || 3.70 gears || MSD 6AL-2 || PST Aluminum DS || many more.

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post #20 of 26 (permalink) Old 02-17-2017, 10:25 PM
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Take it to a dyno shop and have then tune the carb and ignition timing.

66 coupe, '93 Fox seats, Three point belts, 289, Weiand, Hipo manifolds, duel exhaust, T5 trans, Pro 5.0 shifter, 3.40 open, KH front disc, Porterfield R4-S pads, 1" front sway bar, Shelby drop, Spring perch relocation, Shelby quick steer, GT progressive coils (1/2 coil cut), 4.5 leaf mid-eye, Bilstein Street Shocks, Export brace, Monti-Carlo bar, Sub-frame connectors, Performance alignment (+3.5 caster/-.5 camber), 16x7 wheels, 215/55/16 & 225/55/16 BFG G-force

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post #21 of 26 (permalink) Old 02-17-2017, 11:14 PM
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Originally Posted by Ponyboy View Post
Take it to a dyno shop and have then tune the carb and ignition timing.
A dyno will tune for WOT, but a street tune is still necessary. Unless all you do is WOT runs with the car.

1969 MaCh 1 - CHP 427w 10.8:1 comp
TFS 205cc 11R heads || Victor Jr. intake || 950 Holley HP carb || 110* 236/240 .573/.594 hyd roller cam || 1 3/4" ceramic coated headers || 3" exhaust, x-pipe || 14" 6 piston front and 13" 4 piston rear Wilwood brakes || T56 Magnum || SPEC 2+ hydraulic clutch || 9" Detroit Locker || 3.70 gears || MSD 6AL-2 || PST Aluminum DS || many more.

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post #22 of 26 (permalink) Old 02-18-2017, 10:42 AM
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Originally Posted by Claudemiro View Post
Really huh? You don't have it right. The fuel mixture screws ACTUALLY do control the amount of fuel that comes through the idle circuit. There is no magic here. And emulsion is not a noun, it's not a thing per se. And emulsion tube controls the air flow in small amounts, to control overly rich conditions as venturi vacuum increases. This causes more fuel to enter the stream and in some cases, the mixture is too rich. An emulsion tube allows extra air to mix with the fuel. It's still an air fuel mixture, regardless. It's not something special, doesn't get a new name. I know you have a hot engine in your car and that's cool, but your carburetor information is not correct.
This shows exactly what I stated. Fuel comes through the IFR, air comes through the IAB mixes togeather commonly called an emulsion then the amount of the emulsion is at idle metered into the carb/engine by the idle mixture screw.
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post #23 of 26 (permalink) Old 02-18-2017, 10:54 PM
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Carburetor Tuning the Scientific Way

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post #24 of 26 (permalink) Old 02-18-2017, 11:42 PM
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Quote:
Originally Posted by Claudemiro View Post
The fuel mixture screws ACTUALLY do control the amount of fuel that comes through the idle circuit. There is no magic here. And emulsion is not a noun, it's not a thing per se. And emulsion tube controls the air flow in small amounts, to control overly rich conditions as venturi vacuum increases. This causes more fuel to enter the stream and in some cases, the mixture is too rich. An emulsion tube allows extra air to mix with the fuel. It's still an air fuel mixture, regardless. It's not something special, doesn't get a new name.
This is spot on . . .
post #25 of 26 (permalink) Old 02-18-2017, 11:55 PM
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Originally Posted by Woodchuck View Post
Pretty good read. I remember reading that a few times a good while back. Most people say that the power valve should activate at about 1/2 the normal operating vacuum, but I'm in agreement with the author in that link. If you observe a vacuum gauge, you can literally see at what vacuum the engine is asking for more fuel. Usually closer to 2 in of vacuum below the operating vacuum than half. Most Holley's I believe come with a 6.5 power valve, which I find is, more often than not, too low.

1969 MaCh 1 - CHP 427w 10.8:1 comp
TFS 205cc 11R heads || Victor Jr. intake || 950 Holley HP carb || 110* 236/240 .573/.594 hyd roller cam || 1 3/4" ceramic coated headers || 3" exhaust, x-pipe || 14" 6 piston front and 13" 4 piston rear Wilwood brakes || T56 Magnum || SPEC 2+ hydraulic clutch || 9" Detroit Locker || 3.70 gears || MSD 6AL-2 || PST Aluminum DS || many more.

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post #26 of 26 (permalink) Old 02-19-2017, 11:53 AM
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Originally Posted by Claudemiro View Post
Sorry, I didn't learn from just a picture. I had lots of training. Trust me, I'm right. And the noun is an "emulsion tube". The"tube" makes it a noun.

Maybe this picture will help explain, the Emulsion Tube is part of the idle circuit its were air and fuel is mixed togeather
From the IFR (fuel) solid red in picture, Air enters the tube through the IAB mixes together the red hashed lines shown in picture. This creates an emulsion of air and fuel. Emulsion is a noun used to describe a mixture of 2 liquids in most cases say like water and oil that unless agitated seperate. Then the Idle Feed screw meters the emulsion into the engine.

Some carbs actually have screws in place of fixed metering before an Idle Feed Screw some Solex I think and Webbers not sure as havent worked on them for years.

So most just adjust the Idle Feed Screw and thats it. They also just change main jets.
Idle mixture is set properly as stated when turning the idle feed screws best setting half a turn in or out the idle craps out. Most adjust it inward to best idle turning inward a bit more idle craps out but turning it outward from the best setting idle dosent change much though it is becoming richer. Anyway call someone like Nickerson and ask.
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