I've got the Carb blues "Too Rich"

[nutzforporsche]

Hey all!
I wonder if I can get some carb savy from all you experts. I have just installed a set of Weber 40IDF carbs on my car. I swapped out my F.I dizzy for the 009 dizzy and put in my Crane optical ignition. I set the timing, balanced out the carbs and they purr like a kitten. By the way I'm running the F.I cam for the time being . The problem I'm getting is that the mixture for idle is a wee bit too rich and when I crack the throttle linkage, I get way too much black smoke, but the flow is good out my monza exhaust. The engine doesn't hesitant even a little, very responsive. On the carbs I set the mixture screws to two and a half turns out from seat and the air bypass screws to one half turns from seat. The book calls for up to three turns out from seat on the mixture.

The fella I purchased the carbs from ran them on a 2.0 and they are on the same size of engine. His engine could have been modified,..true. So I'm stumped. What do you recommend for jetting to get a real close middle of the road mixture? I have a Weber tuning book and it deals a little too much for the VW area.

I realize that there is never a silver bullet with carbs, each application is different. So I thought that all of you one time or the other have tinkered with carbs. I'm not going back to F.I because to be honest, I've had it with all the hoses, no space to work and watching money fly out of my pocket for parts. Have you seen the price of just the pressure sensor?! Gezzy petes!....
"My apologies for the wineing" :-)
Many thanks in advance!!!
Steve
73' 2.0L Rayco bodied teener

[Tom Perso]

The 2.5 turns from the bottom is only a suggestion just to get the motor running for the first time on the carbs.

You need to screw them in (not too hard either) until you hear that cylinder fall off, then back it back out until it comes back alive. That's the short version too...

Check here for the lowdown on it. Take you time, do it a couple of times if needed, just go slow.

http://www.aircooled.net/gnrlsite/resource/articles/dualcarb.htm

Later,
Tom

[sweater914]

i'm sure the usual cast of characters will holler shortly

i think the car will always run a little rich, the cam isn't right, from what i've seen on the pelican site this seems to a must to switch to a different cam with carbs, my 1.7 was over-carbed with 40's, sure it ran but it looked like a smoke stack on the back bumper, joe ricard just switched from 44's to my old 40's, i'm sure he could give you an ear full

[Dave at Pelican Parts]

I suggest you give the 009 the "float test". Throw it into the lake, and if it floats retrieve it for further study. Put the FI distributor back in, it is a much better match for your engine's needs. The Crane will work fine in the FI dizzy.

Webers may have a fitting already for "ported vacuum". If so, I highly recommend hooking those up to a "T" and running that hose to the vacuum advance fitting (the one pointing away from the distributor body) on the distributor dashpot. This should help a bit off-idle, and supposedly will also help the fuel economy and engine temps at cruise.

--DD

[nutzforporsche]

Thanks for all the input!.

Dave I'll do the test with the dizzy if all else fails LOL.....Trust me I'll even probably set a land speed record with it, just before it hits a cow in the A$$ out back...LOL

Is there going to be a difference in the smoke, no smoke issue if I change back to F.I dizzy? In my limited knowledge "but learning", I'm trying to figure what role the 009 would play in producing a rich situation. The Crane optical controls the firing and the pump is running at 3 psi. I just can't seem to link the problem mentally or commonsense wise. Other than clogged or incorrect jetting or in the post above readjust, the mixture screws. Call it a temporary brainfa%t on my part....sorry.
Thanks!!!
Steve

[1bad914]

Get the CB Parformance Weber book. Or follow the procedures that Tom talked about. I know everyone detests the 009, but I've had great luck with them.

Randy

[nutzforporsche]

Thanks Randy, I'll ditch this book "Weber performance and tuning" by Tom Tomlinson. His knowledge and humor are great for VWs, but right now I think I need something more geared for type 4 engines. I'll head out to their site and get one ordered.
Again to all many Thanks!
Steve

[Dave at Pelican Parts]

The distributor shouldn't change the mixture, but should change the way the car runs.

As for carbs, I'm some approximation of helpless on that one. I do know that every engine is different, and many of them seem to need slightly different carb setups--even when the specs are the same! So it's best not to assume the setup that came with your carbs is right for your engine.

--DD

[CGNJ]

Hi,

Air bypass is used to get equal airflow on each throat of the same carb. So start up the car and warm it up, disconnect the linkage. Fully seat the all of the air bypass screws. Use the air bypass to balance the flow on each throat of one carb first, then balance the flow each throat of the second. Now use the idle speed screws to balance flow between carbs. Then start trimming the mixture screws for each throat.

Hook up the linkage and spend the rest of the weekend getting the throttle plates to syncronize.

Even using the stock distributor with the vacuum not hooked up will work better than the 009. The curve is really short only about 15 degrees and it comes on really fast.

If you are running 40IDF-19, check the jets and venturi sizes against the table in the back of the book. Out of the box they will run but can be made to work better with 32mm venturi.

Carlos

76 (soon to be 2270, it's really close now)

[nutzforporsche]

Carlos,
I'll go back over these babies this weekend. I'll go ahead since you and Dave are very correct, that the level of advance is really hampered with the 009. I'm sure I'll need much more advance before this thing is over. Not sure why I had a brainf%rt over that Dave ??? The good thing I'm only dumb for so long. LOL

I'm going to contact the PO of these carbs and see what/how/changing that was done with theses units or if they are box stock "what does that mean"? I don't know the venturi size, mains, air, etc... All I know is that they are 40IDF Webers. Pretty sad state of affair don't you agree LOL

From that info I can better evaluate what I have verses what I really should have. Trying to tune them right would be the same as driving blind. Speaking of which,...How in the HE-double tooth picks did I type this without my glasses??????

Thank you all!!!
Steve

[nutzforporsche]

ok here is the latest news of the carb rich blues.

I took off the carbs and did a massive clean and reset the carbs just to start it . While having them apart I checked the sizes of everything "jets". Figuring that the carbs were set for another car and the current setup might not work. Here is what I found:

Idle jet 0.50
Main jet 1.50
Emulstion tube F11
Air correction jet 2.00

I double checked the timing and everything is good to go. I just purchased a CO meter and calibrated it to specs. Fired up the engine and began the tweaking with the mixture screws and air bypass screws. No matter what I do, I still run in the 11.0 to 13.0 percent range of which is way to rich at idle. Even if I tweak the air bypass screws she still stays rich. If I briefly crack the throttle to the 3500 to 5000 rpm range it goes richer! Are my idle jet and main too large for a "box stock" 2 liter? I realize that jetting and tweaking carbs for any car is not an exact science, but there has to be a middle of the road "get you close setting". Thoughts?......

Thanks!
Steve

[Tom Perso]

I think the 150 main's are too much. I am running 135's on a 2270 with 44's, get the point?

.50 idles sounds OK, you just might need more adjusting. The mixture screws are just for idle and progression to the mains. Yes, most of the times you are on the idle circuit, but once you get the rev's up, it switches over to the mains.

Regardless, you are way rich on the mains, go down quite a bit.

I've recalled hearing 130's for a 2.0L? Don't quote me.

Later,
Tom

[nutzforporsche]

Thank you Tom!

I'll see if Pelican has jetting and get them ordered. Shoot at this point anything can be an improvement.

Thank you again!
Steve

[dman]

I agree with Tom 150's are to big I'm running 130 mains/55 idles on a 2L with a cam. You may also want to check the float levels.

[nutzforporsche]

Thanks Tom!

Here is what I decided to do once talking with the folks at Carbs Unlimited.

He asked what type of cam and engine size and the 2.0 equates out to a 122.84 CID with a needed cfm of at least 151 . This is with the stock F.I cam. It wasn't too expensive 47 bucks and some change

They said as a baseline you are correct with the 130 something range mains. So I went with the 130s as he suggested. He thought that the idles were a bit too large, so he suggested the .40s. He mentioned that everything else was good to go, for a middle of the road test.


I hope this helps!

Steve

[nutzforporsche]

Doh! How stupid! Never thought to check the float settings! I need to get my head and my A$$ wired together.

I should have ordered a tool or requested a paper template to do that!

[gint]

40 idles are too lean. I agree with the mains suggestions. Try them and adjust the floats before you put in those 40 idles.

[nutzforporsche]

Anyone have a old template lying around to set the floats on IDFs? I can send it back to you.

Thank you,
Steve

[HarveyH]

I have a 2056 with a ¾ cam, Pertronix, Crane HI-6 and PS91 coil. I?m running 40 IDF?s with 28 mm venturies, 45 idle jets, 1.15 mains, f11 emulsion tubes and 2.00 air correction jets. There are several good Weber manuals around, read one or more of them and understand what is going on with carbs. Aircooled.net also has a tech write-up on tuning Webers. Remember that the jet recommendations in the manuals are just starting points, not cast-in-stone requirements.

First off, tuning carbs is all a very inexact science, and can take a lot of trial and error to get things exactly right. Seasonal (and sometimes daily) changes in the weather can affect your carb tuning. The generally accepted theory is that with a constant speed, load, and temperature situation, a carb will provide a better fuel/air mixture than FI. Obviously this does not define the operational characteristics of an automobile. If you change the speed, load, or temperature, a FI system can provide better control of the mixture. If you have a stock engine, it may be better to go back to the FI system and do what is needed to get it operating correctly.

Weber jet tuning for IDF?s breaks down into three basic ranges. Idle to about 3000 RPM is controlled by the idle jets. About 2600 RPM to maximum RPM is controlled by the main jets, and from 4000 RPM up the main jet circuit is modified by the air correction jets. NOTICE THAT THESE RANGES OVERLAP. This means that changing one set of jets MAY make it necessary to change either or both of the others. Changing the emulsion tubes will affect the overlap ranges of these three correction points. Another thing to note on idle jets is that the mixture screw adjusts mixture only at the static idle position. As you open the throttle, transfer ports in the carb are exposed to the airflow and more fuel flows into the airstream. This means that you have to size your idle jets for off-idle running through the transfer circuits and use the mixture screws to set the static idle mixture.

Adjust your synchronization, idle speed and static idle mixture. Operate the car for a while and evaluate what should be done to ONE adjustment point. Make that one change, resync and reset static idle parameters, and run the car some more. Has the change helped? Can it stand a little more (or less) adjustment in that one point? If so, make that change and evaluate the results. Once you?ve got one set of jets right, move on to the next. Remember that the effective ranges of the jets overlap. This means that when you change the mains, you will affect the upper range of the idle circuit operation and MAY need to go up or down a size in your idle jets. High RPM mixture is adjusted using the air correction jets, in reverse logic to the idle and main jet operation. To make the high RPM mixture richer, you must use a smaller air correction jet allowing less air to bleed into the circuit. Again, changing the air correction jets MAY affect the size of the main jets that you need, and that MAY affect the idle jets.

Good luck,
Harvey

[Joe Ricard]

You can set the floats pretty easily by flipping the whole top piece upside down and let gravity tell you whatthey are set to. Then use a machinist ruler to measure 12mm . This setting seams to work best for my 40 IDf's and 10MM was to high and I could see the gas splash onto butterflies.
Remember you will make the most HP at WOT and an air fuel ratio of like 12.5 or 13:1 DON"T WANT TO GO LEAN WHEN YOU ARE GOING FAST.