How to adjust a Carburetor

[Grip-it]

I would like to learn how to adjust a carburetor on my 87' 350 magnum chevy. Is there a procedure I can follow or literature I can read to learn how to do this? Do they make Adjusting a Carb for Dummies?? Ha Ha!

Thanks

[RickR]

A service manual or speciality manual for Holly,Rodchester or Weber is available.

I adjust idle for highest, smooth idle at recommended RPM. Or if you have a vacuum gauge adjust for highest manifold vacuum.

Merc had a Tech Bulliten out a while back, suggesting a maximum of 1 1/4 to 1 1/2 turns out from bottom, for the idle screws on their Weber.

[MOP]

It is a good idea to pull the idle screws completely out and inspect them to make sure they have not been damaged by over tightening. If the have a ring like depression on the taper relace them, if even slightly damaged they can be a bugger to adjust properly. Never seat them with anything more than very light pressure then back out to basic adjustment, fine tune from there.

[KMLFAMILY]

Adjusting the carb. is not that difficult to do.It does take a good ear to do though.1st locate your adjustment screws.You didn"t mention which carb. you have.If it is the Quadrajet they will be located in ft.and below.2 screws, one on each side.Possibly covered over with a tamper proof plastic shield.If so, squeeze cover with small needle nose pliers w/out bending screw.This will crack covers for removal.Other carb"s should have normal slotted screws in ft.or sides. Quadrajet don"t.You will need an idle adj.tool for these sold at your local auto parts store (inexpensive).It is a small flexible cable tool w/ends.Warm engine to normal operating temp.Verify choke fully open.Take note of current rpm idle speeds neutral& in gear.(If you have a problem later with shifting, stalling you will have this # to fall back on).With engine fully warmed and running (neutral gear) turn 1 screw in very slowly(patience)and listen for a minor rpm change. At the change point stop.Then back off screw 3/4 to 1 full turn(Sometimes where it sounds best).Then do the same for the other screw.Now see if the idle rpm speed is still within proper ranges.If not remove throttle cable from carb. only.Then with engine running adj.the idle speed screw.Located near throttle shaft.Adj. to the correct rpm.Need to ck.the book for exact application requirments.Turn engine off.Then make sure throttle cable end slides on easy in the neutral position.If not only make minor adjustment to cable end.
These adjustments are generally done as part of or after a good tune- up.Replacing worn ignition parts can also effect idle speed.Maybe you need that also.I hope this gives you an insight.
Ken