Weber IDF always rich- Please help! Options

[jmill]

With the O-ring missing you'd suck more air from around the jet holder instead of more fuel from the fuel wells. If they leak you'd be lean. To suck more fuel you need to suck less air and pull more vacuum on the fuel wells. Plugged air ducts would do it. Are the air ducts ( orifice above idle jet ) unplugged?

45 idles are too small. Something isn't right. You should be around 50 to 55. How many turns out are your mixture screws?

BTW - you need to get those O-rings in.

[Root_Werks]

(IMG:style_emoticons/default/agree.gif)

There are a total of 4 O-rings per carb, very important.

[FourBlades]

I am no expert but I got a suggestion lately that helped with my rich idle
problem.

An old school VW guy told me to open my air bypass screws 2.5 turns as a
baseline to help get more air into the mix at idle. I was turning my mixture
screws in too much to try to get a lean idle and it was causing a stumble
getting on the throttle. 2.5 air bypass with 1.5 idle mixture screws worked
much better for me. Open the air bypass screws more to synch barrels
and carbs with each other not less.

If you are still blowing black smoke then I would guess something else is
wrong not just adjusted incorrectly.

John

[rhodyguy]

when your car is ilding, is fuel spilling/dribbling out of item #12( the pump jet)?

in addition to the little o rings for the idle mixture screws there should be little metal caps that the springs push against. these caps are not shown in the diagram you have posted. do you own a copy of Tomlinson's Weber Manual?

[tornik550]

I had two o-rings so I put them on the idle jet holders on one carb. I also check the air ducts and I can see the idle jet through so they are open.

I believe that my problem is primarily with the idle circuit.

Turning the idle mixture screws do not seem to make any difference at all. I have them all the way in and I still have the rich issue.

I rechecked to make sure that my float needle and seat were seating ok. I tried to shot low pressure air into the fuel input with the needle closed. I could not hear any leaking air.

I also checked the compression on 3 of the 4 cylinders. All were around 140 when the engine was half warm. I got a phone call so I didn't check the last cylinder until the engine was cool- it was 110 but I am not sure the compression tester hose was on all the way. I do not think that the 110 cylinder (#1) has anything to do with my problem cause I have the rich issue with all cylinders.

I should also mention that I am running a CB performance fuel pump. I was running a fuel pressure regulator however I recently found that it wasn't working properly (it would surge). I have removed it so I do not have a fuel pressure regulator or gauge hooked up now. I had this rich problem before and after having the fuel pressure regulator on however I do not know if the regulator was working properly. I have a new regulator and gauge on order.

I agree that something is clearly very wrong and I doubt that it is a jetting issue since I am already using small jets. I just cannot figure out where the fuel is coming from.

[tornik550]

when your car is ilding, is fuel spilling/dribbling out of item #12( the pump jet)?

in addition to the little o rings for the idle mixture screws there should be little metal caps that the springs push against. these caps are not shown in the diagram you have posted. do you own a copy of Tomlinson's Weber Manual?

I checked looked several times to see if fuel is spilling or dribbling out of the pump jet. I have never seen any at all.

I don't have tomlinson's weber manual (I didn't know it existed). I do have Haynes weber manual.

[tornik550]

Here is a brief summary of what I have tried to figure out the problem. Some may sound stupid but I have tried everything I can think of. I am referring to rich idle only. Nothing has changed anything. I realize there may be some tricks to get rid of the symptoms however I want to figure out and fix the source my problem. I am absolutely lost and frustrated.

-tried different idle jets (larger was all I had but it was just a shot)
-different main jets of many different sizes
-idle mixture screw adjustments to all extremes
-tried 7 different types of spark plugs at different heat ranges
-checked to make sure pump is not leaking
-tried different float heights- anywhere from 10mm-12.5mm
-confirmed float needle is seating properly
-confirmed air ducts about idle jets are patent
-tried to run without air correction jets just to see what would happen- no help
-rebuilt choke system after I found the starter jets were stuck- no help. out of frustration, i then tried to plug the starter circuit so there would be absolutely no leakage- no luck
-tried various timing setting- no change in rich issue.
-found crack in one intake manifold- no change
-tried different spark plug gaps (0.28-.45)
-tried different venturi size (why not give it a try)- tried 32mm and 34mm
-added the needed o-rings to the idle holders that I forgot- no help

Clearly there is something very wrong. If something were this wrong it seems like it would be somewhat obvious. I think that I have tried just about everything and I am extremely lost and frustrated. I hate the thought of taking my car to the shop but I may have to. I have a young child and my wife is pregnant. I can see her getting a bit angry with me if drop $500-1k taking the car in.

[rhodyguy]

you need an o ring for each idle/air mixture needle screw. the caps also. actually, Tomlinson's book is a CB item. you get it from them. i don't think you are running on the idle circuit at all when everything is hooked up. i note in your other thread you state you can achieve a stable low idle with the linkage disconnected. do the mixture screws have any effect then?

[FourBlades]

Buy a new set of carbs for $500-600 before taking the car in anywhere...

Did you ever check if your manifolds are flat and sealing well? Mine were warped from the factory and my car ran like shit until I smoothed them and got them sealed right.
Mark wrote a post about it a while back.

John

[tornik550]

I may have just found my problem. I was having rich issues at all rpms. I previously checked and found that when I thought I was using 120 main jets, I found they were bored out by the PO.

In retrospect, I should have checked to see if the PO also bored out the idle jets- it turns out that he did. 45 is printed on the idle jet. I think he tried to bore it out to 55. I think that it is somewhere between 0.55mm and 0.60mm (I only have 55 and 60 drill bits- 55 is very loose, 60 will not fit).

Can an idle jet discrepancy of 5-10 cause a significant rich mixture issue (even with the mixture screw turned all the way in?

[tornik550]

Buy a new set of carbs for $500-600 before taking the car in anywhere...

Did you ever check if your manifolds are flat and sealing well? Mine were warped from the factory and my car ran like shit until I smoothed them and got them sealed right.
Mark wrote a post about it a while back.

John

I did not check, I will do that.

[jmill]

With the mixture screws turned all the way in your car shouldn't run. You should have no fuel flow from the idle jets. There is one of 3 things going on. (1) Your mixture screws are the wrong ones or junk. (2) The mixture screw seats are all screwed up and the needle doesn't seat. (3) You have fuel flowing into the carb from somewhere else.

Remove your mixture screws and take a good picture and post it. They should look like a sharpened pencil. The DAPO might have replaced them with the wrong ones, filed them or they are just plain junk. If the seats are screwed up it's harder to tell.

[tornik550]

I want to confirm that my engine will run with the mixture screws in all the way. I will do this when I get home. The reason that I ask is because I currently have the screws out 1 full turn and it runs. When the engine ran with the screws all the way in, I was doing experiments on other carb parts which may have aloud the engine to run. I am not sure that the engine would run if I turn the mixture screws all the way in considering that I have all the other settings around normal.

I greatly appreciate every bodies help. Imagine how difficult it would be to figure out our car problems with out forums like this. Books are only so helpful.

[tornik550]

I forgot to mention that my mixtures screws look decent to me. I do not see any evidence of the PO filing them or anything. They look clean. The appear like a nicely sharpened pencil.

[tornik550]

I just got in from the garage and I am very pleased however I do not know how to interpret my results.

I put new spark plugs in, attached a new fuel pressure regulator and fuel pressure gauge. I turned all of the idle mixture screws all the way in. I tried to start the engine. It started right up and ran as smooth as I have every heard a 914 run. I was shocked by how smooth it was running. It sounded like a completely different engine. I let it run for a few minutes at idle then turned off the engine. Pulled a spark plug and for the first time ever the plug was not fouled. It looked exactly like it did when the plug was brand new.

The engine is running great at idle but from what I understand, it should not be running at all with the idle mixture screws all the way in. What does this mean? I am confused (as aways (IMG:style_emoticons/default/blink.gif) )

Thanks again!

[jmill]

Your butterflies are misaligned. (see fig. C ) When your butterflies are closed a progression port is on the vacuum side of the butterfly. You'll pull fuel from the progression port and your car will run with the mixture screw closed. When the mixture screw is open you'll be way too rich.

Pull a carb off and turn it upside down. The butterfly should close nice and tight and you shouldn't see progression ports. If not loosen the butterfly screws and let the plates slide into place. Tighten back up and see what you have. If you still see a progression port you can buy new carbs or file the butterfly (Fig. D).

[tornik550]

Your butterflies are misaligned. When your butterflies are closed a progression port is on the vacuum side of the butterfly. You'll pull fuel from the progression port and your car will run with the mixture screw closed. When the mixture screw is open you'll be way too rich. Sounds like exactly whats happening to you.

Pull a carb off and turn it upside down. The butterfly should close nice and tight and you should only see the mixture screw port. If not loosen the butterfly screws and let the plates slide into place. Tighten back up and see what you have. If you still see a progression port you can buy new carbs or file the butterfly.

I actually tried this last week. If I back the idle speed screws out so the lever doesn't touch then the butterflies close completely and I cannot see any of the progression ports. There is one port that is very close to the butterfly edge however it is not exposed if the idle speed screws are backed out completely. IIRC there is one progression port exposed when idle screw is set to about 900 rpms.

Is it possible that all of my idle mixture screw seats are screwed up and that is causing a little leakage into the intakes? I would find it unlikely that all would be messed up but who knows.

I plan on rechecking to confirm that no progression ports are exposed however I am fairly certain that none are (assuming the above conditions).

[tornik550]

I did not see the image at first. I think that I may fall into the "C" category from the diagram when the idle speed is set. SO if this is the case (I will confirm tomorrow afternoon) then would the best way to fix be shaving the inferior butterfly edge on the progression port side?

If this is the case, how would this happen to both carbs?

[jmill]

I doubt all the seats would be junk. Stranger things have happened. The misalignment fits all your symptoms perfectly. Thats my best guess. I would try and loosen the butterfly plates and rotate the shaft closed with the carb upside down. The plates will center themselves. Tighten them up and see what you have.

[jmill]

If this is the case, how would this happen to both carbs?

Poor machining out of the box, improper assembly. Do they say "Made in Italy" on them? Before you go filing plates make sure they are centered.