Welp, i've decided i'm going to rebuild my quadrajet and learn how they work.
NOTE: This will probably be the most, slow, anal, and to many of you, a highly annoying thread. Please be patient with me as i know next to nothing about carburetors and fuel systems. It's sort of like someone who has to learn to walk again---it will be a slow and arduous (sp?) process. In fact, it would not suprise me if even Liz Taylor knows more about carburetion than me (she's been around). On top of that, she has more money than me. How can i compete?
On the other hand, this thread may be very exciting in that it has never, ever been done before on the net----- an in depth, highly detailed discussion regarding the disection, discussion and analysis of the rochester quadrajet! We are going to make history! And you're welcome to come along.
So the first thing is, i remembered that i had an unused reman dualjet sitting on the shelf (this was when i had a 3.8 buick powered monte carlo) i purchased the carb for learning purposes and while that may sound strange, it really works for me; i have to physically see something in action in order to truly undestand it. My mind is not "mechanical" enough to undestand a concept if someone just explains it. i'm more of a driver than a mechanic.
i figured it would be ideal, for now, to examine this carb for several reasons:
a) Because it has not been used, it doesn't smell so i can do this indoors where it's nice and cozy; It is getting colder here and i don't yet have the practical ability to heat my garage. i am looking towards kerosene.
b) Dualjet is basically a quadrajet minus the two back barrels and this is good enough for now because:
c) i need to learn the very basics. For instance, in order to get the right rebuild kit, i need to know the model number?, jet sizes? etc.
i will eventually (soon) take the quadrajet that needs the rebuild off the engine and move to the garage.
So anyways, first off i noticed that after taking off the choke cover, the choke coil lever (fig. a) is supported by the choke coil and after the coil starts to relax ( i'm assuming the wire to the electric choke is connected to a temp sensor and at a given temp it "tells" the wire to activate the choke?) the choke coil lever will move downwards in the direction of the arrows. This lever is also connected to the actual choke door and as it moves downwards the choke blade also opens to let more air into the carb.
The intermediate choke shaft? (fig.c) is also apparently connected somehow to the choke coil lever and pushes against fast idle cam (fig.d). The fast idle cam is somehow and apparently connected directly to the throttle arm on the other side. As the choke coil relaxes, the intermediate choke shaft will also move fowards/downwards which allows the fast idle cam to move downwards/forwards which, in turn, allows the throttle to be closed slightly more and thus rpm drops as the engine warms up?
My questions at this point are:
and let me preface by stating that by the time i started driving, most cars were electronic fuel injected by then. So, this further contributes to my ignorance. We just turned the key and off we went.
1) i never really paid attention to the step down/tapping the throttle thing with the throttle to get it off high idle; i usually just drive away gently right after starting because i'm not the type that believes in having the engine just chugging away for no apparent reason. i did see my parents (when we had carbed cars) do it, because they apparently believe in "warming up." But even then, i never really paid much attention.
What i'm wondering is, the fast-idle cam, as far as i can see, apparently has nothing pulling on it in the direction of downwards/fowards. So, i'm wondering, is the rpm supposed to drop automatically, or do you always have to tap the throttle to get the rpm's to come down?
2) What is the purpose of turning the choke cover clockwise or counterclockwise?
3) i noticed that the rear vacuum break diaphram (fig.b) pulls a little bit on the choke door whenever the engine is running which allows a little air in because, apparently, even a cold engine needs at least a little air to run. Why didn't rochester simply put a stop screw in for this purpose?
4) The front vacuum break diaphram (fig.e) is not connected to anything. What is it supposed to do?