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Discussion Starter · #1 ·
I was advised to buy a fuel to air ratio (Fast or Holley ) wide band O2 sensor hook up to tune in my carb. Does anyone have experience with any of these or recommend one over the other? I am getting black smoke and black plugs plus smelling like exhaust after driving the car. It's a 700 cfm Holley carb sitting on a 100hp nitros plate which is sitting on top a Weiand 142cid supercharger. My city and highway driving is horrible on gas and I am tired of the family smelling like exhaust after driving the car. any advice is appreciated.
 

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Discussion Starter · #5 ·
I pulled it out of the box 12 years ago and put it on the blower. Never had this set up tuned which is why I was thinking I need a wideband set up to do that.
 

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bentwings
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Look at Innovate Motorsports AFR. They have several. Also data recording is available. There is a tech info thread on their site.
If your carb is 12 years old it may not have the power valve check valve. The book shows how to add this.
Get the Holley carb tuning book......memorize it.....or at least get a very good understanding of how the carb works.

The wide band O2 sensor is mounted in the exhaust pipe.

The carb has a port for manifold reference vacuum, it needs to be hooked up.

You need to look at your distributor. It needs full advance by about 2100, 2200 rpm and around 32-34 degrees total. I like to run vac adv too. Mine is adjustable and has about 12 deg?
 

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^^^I second the Innovate setup. The only difference I see between the setup above and mine is I am not using Vac advance, this is on an 8-71 383.

I would also think you must have large primaries if only using a 700 with nitrous, and your carb is obviously not blower referenced like bentwings mentioned above.

What's your idle rpm and is it rich at idle?
 

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Discussion Starter · #10 ·
I have installed the air to fuel ratio meter. I am getting around 14.5 at idle and anywhere from 10 to 11.5 on the primary jets. When I kick in the secondary side I get 11.8 to 12.5. This is without nitrous. Reading up it seems as though I may need to lean out the primary side by reducing the jets. They are at 72 now. Does anyone have any thoughts on a good number to shoot for?
 

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Hotrodders.com Moderator
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that is a boost referenced carb. To start with are you sure you have the boost reference port connected to a vacuum source. If not the power valve will be hung open and it will run real rich. While an A/F gauge is a good idea I think it is pretty obvious you are running rich.
Have you checked for vacuum leaks. What is the vacuum reading on this engine at idle.
That carburetor requires a vacuum line from the manifold to the boost reference port. if you don't have it you need to fix that first
 
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