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How do I adjust air/fuel mixture on my Holley 750VacSec?

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Old Sep 10, 2002 | 06:53 PM
  #1  
Cruz'N Bruz'R's Avatar
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From: Cincinnati, OH
Car: 87 Iroc Z
Engine: 383ci.
Transmission: WC-T5
How do I adjust air/fuel mixture on my Holley 750VacSec?

E-test is coming quick and I'm running pig rich. any help?
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Old Sep 10, 2002 | 08:34 PM
  #2  
five7kid's Avatar
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From: Littleton, CO USA
Car: 82 Berlinetta/57 Bel Air
Engine: L92/LQ4 (both w/4" stroke)
Transmission: 4L80E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
At the top of this board is a sticky post called "Welcome to the Carb Board; Please Read". Towards the bottom of that post is a link called "Holley Techical Information".

When you click on that, near the top of the page you'll read, "A carburetor's functions can be easily analyzed and understood but at the same time it can be frustratingly difficult to troubleshoot problems associated with it. Many times a carburetor is looked at as the prime culprit or the main cause for a myriad of other engine-related difficulties that might exist. Therefore, it's best to check and verify the condition of the complete engine system before proceeding with any carburetor work."

Start there, see how it goes. Happy reading and troubleshooting.
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Old Sep 11, 2002 | 03:29 AM
  #3  
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Joined: Sep 2001
Posts: 6,111
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From: Ontario, Canada
Car: 1988 Firebird S/E
Engine: 406Ci Vortec SBC
Transmission: TH-350/3500stall
Axle/Gears: 7.5" Auburn 4.10 Posi-Traction
I don't know what year your car is or wether you can sneek it in under the "Hot rod clause" but I can tell you you haven't a chance in hell of making that thing pass. Ha Ha Haah!!!


I could sit here and tell you to do this and that, but it'd be a waste of time. It's just too radical to get good smog numbers.

Pull the motor and install a smog friendly sb and take it to be tested. then reinstall your motor.

Try this:
Install
New spark plugs!
a 3.5" primary power valve
#66 primary jets
set initial timing at 3* btdc @ idle speed 800rpm n
plug vacuum advance into "ported vacuum"
That is the one with no vacuum at idle.
remove the carb and observe the position of the throttle blades to the idle transfer slots. The should only be showing by about .025/.030" open the sec idle stop to compensate for the re-djusted primary idle.
Hook up a PCV valve and valve cover breather.
( this will lean out the idle and cleanup the crank case fumes)

If the manifold exhaust heat raiser path is blocked off;(gasket)
open it up some ( remove manifold)
to allow exhaust heat to heat the manifold)
If you have a performer manifold to throw on, do that.
Cause that Torker II sucks for idle fuel distibution.
adjust the carb for best idle vacuum once it is fully warmed up.
then lean out the idle screws a slight amount till the rpm just starts to drop. If you don't have a choke hooked up it will run like s**t till it is warmed up, don't worry about that.
As long as it runs good when fully warmed up.
Change the oil and use Sunoco 94 ultra.
Be sure the car is fully warmed up before you test it.
Adjust the idle mixture screws for best idle -20/50rpm lean roll drop just before testing.
Try this with cats installed. It could get your throu the 1980
standard (hot rod).

Last edited by F-BIRD'88; Sep 11, 2002 at 03:33 AM.
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Old Sep 11, 2002 | 05:07 PM
  #4  
Cruz'N Bruz'R's Avatar
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From: Cincinnati, OH
Car: 87 Iroc Z
Engine: 383ci.
Transmission: WC-T5
Well, all i was looking for was a turn the screw clockwise/counterclockwise kinda thing, but thanks Firebird 88.

Five7Kid: What exactly is the point of a message board if every question asked your told to reference an older post. i'd like some real time answers.
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Old Sep 11, 2002 | 05:52 PM
  #5  
Jester's Avatar
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From: Homestead, Fla
The whole point of the sticky five7kid referenced is so we don't have to keep answering basic questions over and over that have been asked 500,000 times. Ergo why it says PLEASE READ in the title, and why everyone that posts here is expected to do so.

We're here to help with problems and to help people learn, NOT be a replacment for the instructions for people too lazy to read them and learn for themselves.
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Old Sep 11, 2002 | 10:03 PM
  #6  
F-BIRD'88's Avatar
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Joined: Sep 2001
Posts: 6,111
Likes: 53
From: Ontario, Canada
Car: 1988 Firebird S/E
Engine: 406Ci Vortec SBC
Transmission: TH-350/3500stall
Axle/Gears: 7.5" Auburn 4.10 Posi-Traction
Think you're going to need a little more then a turn a screw
in or out kind of thingy. ha hhaa ahhahha!!!!!

But good luck to ya.....
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Old Sep 12, 2002 | 07:58 PM
  #7  
Cruz'N Bruz'R's Avatar
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Joined: Sep 2001
Posts: 2,031
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From: Cincinnati, OH
Car: 87 Iroc Z
Engine: 383ci.
Transmission: WC-T5
Actually, sorry if offensive, but I think sticky's used to replace common questions are things put up by lazy mod's and regulars who don't really enjoy answering questions directly.

Don't worry, i won't take anymore of your precious time.
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Old Sep 17, 2002 | 09:52 AM
  #8  
five7kid's Avatar
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iTrader: (14)
 
Joined: Mar 2000
Posts: 43,187
Likes: 43
From: Littleton, CO USA
Car: 82 Berlinetta/57 Bel Air
Engine: L92/LQ4 (both w/4" stroke)
Transmission: 4L80E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
You're still missing the point, which is the basics need to be covered before any real help can be provided. There are a host of reasons an engine will run "pig rich", and many times it's not the carb's fault.

As F-bird noted, you've got mods that typically aren't compatible with emissions testing. Plus, you didn't provide some vital details such as what distributor you're using, exactly what kind of Holley you've got, what you've done to it, etc.

With that cam and intake manifold, I doubt you'll ever get it clean enough to pass sniffer. To say nothing about visual (if you have it - I don't know if you do or don't, and you didn't say). But, have you at least read the suggested info, and what have you tried so far?
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