Quadrajet Problem Solving > Dialing in your rebuilt Quadrajet carburetor

Q-jet tunning fresh rebuild.

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Schurkey:

--- Quote from: Toronado on December 23, 2009, 07:22:17 PM ---Im curious why is it best to run idle at the leanest setting possible?
--- End quote ---
Not the leanest possible.   Find "best idle" (I use a vacuum gauge--about ten times more sensitive than a tach) and then go just a little lean.
Otherwise you're blowing incredible pollution out the tailpipe; and the excess gasoline will wash the oil off the cylinder walls and contaminate the oil.  From both the environmental and the engine-wear perspectives, overly-rich mixtures are detrimental.

Cliff Ruggles:
Correct, not the leanest possible settings, but the best settings for the engine.  This is done by finding the lean "tip-in", then backing them out for highest vacuum, highest rpm, and best idle quality.

In most cases this will be about 1/2 to 1 turns from the lean "tip-in" point.

The idle system can certainly effect transistion, so it needs to be able to delivery adequate fuel thru the off idle transfer slots.

A "generous" idle system will not make up the main system being insufficient, so both items should be set up exactly for the application.

The quadrajet and Thermoquad are the best carburetors every designed for smooth idle/off idle and light throttle opening performance.  The small primary bores and booster arrangment is very efficient, and highly sensitive to throttle opening/vacuum changes.  With careful and correct tuning they will delivery perfect throttle response, and excellent economy.

Even so, non of these things have much effect going to full throttle, as the pressure above and below the throttle plates is equalized, and the accl pump, secondary POE, and main jets/secondary metering rod become the main players.....Cliff

Toronado:
Thank you guys..... :)
I used the information you provided, now the car
has great response from stop to main fuel circuit.
Its very smooth & doesn't jerk forward in transition, even when the secondaries
open its a very smooth transition (like fuel injection) now the car has a very fast acceleration from stop to WOT without any lag through all the gears (constant pull).
Unlike some incorrectly matched carbs and engine combos, its not snappy off
the line then lags, then will jerk
forward when secondaries open then lags, no smooth power band. Just goes to
shows a rebuild isn't much without tuning it correctly.
Now my car is "SCARY" fast.

Schurkey:

--- Quote from: Toronado on January 28, 2010, 12:59:09 AM ---
Now my car is "SCARY" fast.


--- End quote ---
When you're ready to start work on the suspension of that Toronado, so it isn't so scary...let me know.  I can help.

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