I've had a weber dfav ( holley 5200 whatever ) for about a year now, and I thought that the procedures for getting it running right were needlessly obscure.

Baselines:
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main jet: 140/145
Air Corrector: 165/175
E-Tube: f6/f6
Idle jet: .45/.50
Idle Air: 1.50/0.70
idle mixture screw 2 turns CCW from bottom
Idle speed ~ 1 1/2 turns from first contact.

** these values = +/- one step are a baseline. The car will run like this, not ideally but you could.
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Definitions:
I feel that some explaination of the jets would be helpful.

Main Jet: This is in the fuel bowl, it controls the maximum amount of fuel to enter each circuit . It has final control over the mixture at WOT, since if it's too small you will always be lean no matter what you do. Likewise too big and you'll be rich to the point that you can't compensate.

Air Corrector: This controls how much air flow it takes to activate a circuit. Means if you should keep changing these down till you develop a flat spot in the throttle. there can be as many as 3 distinct flat spots, you'll probably only ever experience 2, the first caused in the primary at about 80% throttle and extending to lower percentages as it gets exceedingly larger. The second is in the secondary the remaining % of throttle range starting at WOT and extending down as it continues larger. The third is caused by those idle air correctors, but those should never be messed with, you can't even order them. But if you had a pesky idle problem, you might want to find them and make sure they're installed, not blocked,etc... A flat spot around 2000 rpm would be idle jets too small.

E-Tube: Misunderstood emulsion tube, it's a complicated part that regulates the A/F ratio the numbers of holes and where they occur work it's magic, they are found directly under the air correctors and shouldn't be mucked with. Make sure they're baseline.

Idle jet: It's the idle jet, it controls how much fuel is delivered at idle. It won't significantly effect the AF ratios for driving. Fix idle problems here. One thing... If you've reached a very small idle jet you might want to use larger ones and lean down the main jets ( tiny idles plug easily and that would be annoying ) A flat spot around 2000 rpm would be idle jets too small.

Idle Air Corrector: Suppose your car just won't idle but otherwise ran fine, this would be why. It also might be responsible for cars that idle at 2000 rpm and can't be slowed, because it's missing or plugged. You shouldn't need to touch these.

So now you understand what the parts do.

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Setup priorities:

1. eliminate vacuum leaks

2. install a secondary fuel filter of some kind to capture tiny particles that seem to end up in the carb no matter what.

3. set advance. Webers seem to like lots of advance, so give it all you can ( don't detonate, don't give it 30 deg static, be reasonable, I have 7 static and it's pretty good, as much as 12 )

4. make sure you're using ported vacuum (off the carb body ) if you're not using it understand why.

5. Set idle mixture screw = 2 turns out

6. set idle speed 1 1/2 turns out

7. try to start the car
7a. let the car warm up... a challenge perhaps, but it needs to be warmed up.

8. if it runs turn idle mixture screw clockwise till the car runs worse, then turn counter clockwise till the idle speed picks up, somewhere in there will be a point that sounds best. If that point is making it idle super fast turn the idle speed down, you should be able to get the idle down ( if not that's a symptom of something. )Don't worry too much about how much in or out the screw is, the sharpness of the point at the end of it has changed over the years, so if it's more than 2 1/2 turns out it may not be as bad as it once was. If the car is making a noise like sucking the bottom of a cup with a straw, then your fuel bowl level is too high, either the needle valve is stuck, or it's leaking or someone didn't tighten everything down, but it'll be running too rich and the gasket will probably be wet when you take it apart.

9. so you've made it past idle setup, now blip the throttle a bit in neutral, do it slow and mind your rpm, does it gain rpm smoothly and not bog or have other issues up to 1/4 throttle? If so then you can try to drive it, don't go far, don't go in traffic, go down the block, take notice of how the car responds from a dead stop, you probably wont get past 1/2 throttle, any flat spots? if the flat spot is idle - 2000 rpm then it's likely that your primary idle jets are too small. if there's a flat spot further up in the range it's the primary air corrector being too large. Don't worry about WOT now!

10. Go home of wherever and make adjustments needed based on that road test, take note of how the car shuts off too. Webers without anti dieseling solenoids are fussy and tend to run-on. But shouldn't backfire, or afterfire ( one's out he carb and the other is out the tail pipe, having a catylitic converter make make this a problem )

11. Having an EGT ( exhaust gas temperature ) gauge will help with this part, otherwise it's butt dyno or the real dyno. You can also use O2 gauge if you have one. You've made it this far you're almost there. Now is secondary circuit tuning, you can only do this at WOT, so take that in mind when choosing a place. Your air correctors default value is from a 2 liter engine, so you will need to make them smaller, just keep making them smaller till that WOT flat spot goes away. Your smaller engine needs less fuel than the 2l default values, so you'll want to make the fuel jets smaller too that will make the mixture leaner. If your idle jets are really small, make the fuel jets smaller instead, and bring the idle jets back up a size or 2.

You should now have a car that is quite a bit snappier, it may be very touchy now, i suppose the final call comes out to what you like to drive, but you'll understand how to change things now.

At this point you may want to take the car to somewhere with a wide band emissions monitor and a dyno and perfect it, but you'll have a running car in any case.

corrections / comments?

To THe Tech Section Datman!!!!!!

Done. See Tech Section article: Weber 32/36 Carburetor.

Thanks to B210sleeper!

here's an important thing that keeps happening to me.

Car is running in some way, time passes car mysteriously acts weird.

Why?

A. Needle valve stuck, car probably slurps and runs super rich
B. Idle jet/s are plugged.

I keep having this problem where tiny bits of stuff get in and plug up the jets, I have a filter before the pump and the one in the carb, and little tiny bits of stuff still end up in the fuel bowl, I'm trying something new, a really really strong magnet on the first fuel filter to see if that helps, the other choice is a filter that gets very tiny particles.

This fits in with what i was saying about not using #40 idle jets as they clog so easily.


other info:
formulas ( for those inclined )
Main jets ( fuel jets ) : 4x venturi ( venturis are 26/27) so 104/108 minimum
Air Corrector: main jets + 60
Idle Jets: There doesn't seem to be any simple way to get the idle jets sized, which is why there are baselines.

Did you know?
Fuel bowl level has a profound effect on if the car has a tendency towards being rich or lean. So when my car ran totally rich and backfired turned out to be caused by a super high fuel bowl level caused by the needle valve seat not being screwed in tight and leaking lots of fuel all the time. So I could never lean it out.

Quote:I've experienced the same problem. One time, I cleaned out the jets in a rest-area along Interstate 5 -- at night with no flashlight and only a reversible screwdriver! Surprisingly, it worked better after that ..

i have this thing where i need to have all the tools to do pretty much any service in he car at all times ( including a full weber jet kit! ). So I just pull over anywhere pop the hood turn on the inspection light ( if needed ) and go to work.

So most of my driving is currently form home and back to work, so everytime i park I tweak the jets more.

jets:
AC: 150/165 | fuel: 120/135 | idle: 65/55
notes:
has a rough spot at about 1/3'd throttle
needs to be richer in the secondary idle jet ( i think )
Turned off perfectly this AM
larger idle jets are GOOD! - less plugging up!!!!

if you don't like road tests, there is a procedure in the book about taking the idle stop up to where the progression circuit kicks in and what not, I'll have to re-read it and see if I can paraphrase it.

was annoyed recently by 2 things:

1. car lurches in shifts, the power just comes on too strong

2. car is probably running lean, as the exhaust smells horrible ( suffocating CO awful )

Solved by:
Lurches were probably caused by idle being set too low, there are 2 things to consider with the idle, 1. it's how fast the engine minimally turns, 2. the location of the throttle butterfly, if set too low will cause an annoying double dip sort of thing in the airflow. I think we need to just accept that a tiny engine is going to idle a little higher with a weber than it did stock, shouldn't be a problem.

nasty smell solved by taking the primary fuel jet up to 130, and making the secondary idle a #50 instead of #60 as it was before.
Also we set the idle mixture screw since that is what affects the idle mixture - car has no smell in exhaust now.

car goes well, low end torque good, topend pretty good. this is a round port A15, so lowend is always going to be stronger.

gas milage has been 21 - 25 mpg havent calculated recently, but settings have been changed many times, but on 1 drive in big mountains at 60 mph for about 100 miles still averaged 25 mpg.