I know didly about tuning a 4 barrell carb. I have an edelbrock 2 screw carburator and I wanna know if there are any quick tricks to tune it up. I heard one...turn it all the way in and then 1 and a half revolutions back out. is that accurate? I also need to set my idle screw so that it idles at like 750-850 rather than 1000. Its attached to an 85 chevy 350.

Is it the Edelbroc "Carter" version or one of the "Quadra Jet" version?

I have never messed with the carter, but the Qjet is simple. To make the basic adjustment you turn each screw to adjust for max vacuum.

You really need a vacuum guage, timing light and a tach. Set the timming, set the idle speed and then adjust for maximum HG of Vacuum. On a stock motor with out a high lift cam you should get like 17 inches of steady needle vacuum if the motor is in good shape.

Vacuum gauge is a kick ass diagnostic tool...check out a text book on automotive repair for more than you ever wanted to know about it.

There is a great video on Qjet tuning and building sold by northern autoparts. for like $20.00 naparts.com ???

-Stumbaugh

stumb is right! get yourself a good vacuum gauge.

use this basic order:

1) set timing (with a good light inductive pickup)
2) set desired Idle speed (use the throttle stop screw & a Tach)
3) hook up vacuum gauge and adjust the low speed mixture
screw for maximum vacuum reading around 12-18)
4) Reset desired Idle speed (step 3 may raise or lower idle speed)
5) If your carb is equipped with Mid or Hi mixture screw set it for
max vacuum at about 2500 RPM.
6) Test drive the truck.
7) Does it hit hard when you stomp the pedal or fall on it's face?
if it stumbles or falls flat on it's face you probably need more
accelerator pump. if you get grey/black smoke or smell fuel
you need less accelerator pump.
8) When you think you have it running right then run it for a day
and check the plugs, the insulator around the electrode should
be a light tan/brown color. if they are black you are too rich
and if they are oily you need to think about rebuild.
9) if the plugs are pure white, you are probably running a little
bit too lean, you need to richen the mixture in the mid range.

These tips apply to any carburetor, but are not the be-all end-all of jetting/tuning. I reccomend learning on a holley because they are so simple. There are many good books, talk to some hotrod shops, carb tuning is not an art it is a science, anyone can learn.

These tips apply to any carburetor, but are not the be-all end-all of jetting/tuning. I reccomend learning on a holley because they are so simple. There are many good books, talk to some hotrod shops, carb tuning is not an art it is a science, anyone can learn.

Well said. :smokin: