Carbs loading up

[SkrapMetal]

What does it mean when the carbs are "loading up"? I'm a carburetor newbie so to speak. I've taken the car to 3 different people and they can't figure out why its happening, so I may just end up tackling it myself. I have dual 44 webers. Mains are 140's, other jets are stock. The last guy told me 140 was too big... Lots of hesitation and backfiring going on... Help?
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oo9less since 2007
-72 Ghia-

[mharney]

Read:

http://waitresses.servebeer.com:81/vwpage/idf/index.htm

Too much fuel means jetting, fuel pressure, needle and seats leaking, etc. Other causes could be weak spark.

[SkrapMetal]

Thanks! I actually already had that site saved in my favorites How do I check to see if my fuel pressure is too high? I'm getting terrible gas mileage, and I have a couple of plugs that keep fouling because they're caked with carbon build up.
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oo9less since 2007
-72 Ghia-

[mharney]

Are those plugs on one side of the engine?

You check your floats as per the article. You check your fuel pressure per a fuel pressure gauge. If you have a mechanical pump, you will want to check it at higher RPMs.. it will change a little.. set it for 3-3.5 psi at its maximum.

Personally I prefer electric rotary fuel pumps. They work well and are already "regulated" at 3.5 psi if you get the right one.

[SkrapMetal]

Yes actually, cylinder #2 plug is black as black can be. #1 is just a little black, the other two are tan which is good. I'm gonna crack them both open and set them to 11mm (if they're not already there).

I'm not really educated when it comes to fuel intake/carbs etc. Stupid question but, after I get a gauge, how do I go about adjusting the fuel pump? It's a chrome, stock looking one. I guess theres no sense messing with my carbs until this checked out first
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oo9less since 2007
-72 Ghia-

[John M.]

[mharney]

[SkrapMetal]

That sounds too easy... easier the better. I'll pick up a fuel pressure gauge for this weekend, a 6 pack, and then post my results. Thanks!
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oo9less since 2007
-72 Ghia-

[mharney]

Suggest you leave the 6er until you are done.

[SkrapMetal]

Alright... picked up a fuel pressure gauge, fuel pressure is reading just under 3 psi. The float on the left side was good, the right side was reading about 16mm so I set it to 11mm, and put it back together.

The popping and backfiring stopped! Now.. I have a new problem. The throttle arm on the left side retracts further than the throttle arm on the right side with the idle speed screws out all the way, causing it to idle fast. Is this where I have to adjust the mixture screws? Can this be done without a synchometer? Tomorrow is sunday and the vw store is closed so I can't pick one up till monday. I just need to get it adjusted close enough to be able to drive it there.
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oo9less since 2007
-72 Ghia-

[mharney]

You really need a flow meter to set up the flow on each side the same. In lieu of one of those you can stick a tube down the throat on one side and listen to it and adjust the other side to have the same pitch/sound, and you'll be close.

Another trick is to asjust the mixture screws for fastest idle and then pull one plug wire from one side and measure the idle speed drop. Reconnect it and pull one from the other side.. if it drops more, that side is flowing more at idle. Balance them this way and you'll be close.. when done, re-set the mixture screws, and synch your linkage again.

[SkrapMetal]

Well, its a little better. Still very little power, but at least there is no backfiring and no popping when I downshift. Adjusting the float made a world of difference. It's driveable so I can get to the parts store and pick up a sync and finish tuning. I didn't touch any other screws other than the idle mixture and idle speed screws. I'm wondering if any of the other adjustment screws have anything to do with the power loss
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oo9less since 2007
-72 Ghia-

[SkrapMetal]

Update....
Bought an electric fuel pump and my idle fluctuation has disappeared (what a world of difference!). Still running pretty rich, but mostly on cylinder 2 and I can't figure out why. I'm now running 55 idle, 36 vent, 200 air, 145 main with F11's. I had 140 mains, but when I really stepped on the gas, it seemed like it didn't want to move so I switched to 145's and it was somewhat better. I'm fouling out my plugs just after a short easy drive. I want to experiment a little with my jets, but now I'm confused on what to try next. Should I go down a size on my idles or airs?

I also have an engle 120, and 043 heads with 42 x 37.5 valves, if that matters
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oo9less since 2007
-72 Ghia-

[mharney]

Wow, like 5 months ago! hehe

Of primary importance to tuning them correctly is the float height adjustments. Anything other than correct and you are wasting your time.

If cylinder 2 is the one that is running rich, I'd inspect the idle jet in that position, in fact, I check them ALL.. Sometimes there is a bad one in there, i.e. wrong size for what it is stamped.

What are you basing the rich running on.. plug color?

Are you able to turn the idle mixture screw in until it starts to drop off on that barrel? If so, how much more does it turn before it bottoms out in the seat?

If you're stomping the gas at anything below about 3000 RPM, it might just want to drop out due to air speed and the cam's power band, or it could be accelerator pump adjustments. The slow pedal approach in a higher gear will tell you if it is jets or accelerator pumps that are your problem.

[SkrapMetal]

I completely dismantled that carb (even though it's fairly new), soaked it, cleaned out the passages with compressed air, and reassembled it with new gaskets. I adjusted the floats on both carbs to exactly 10mm, with the gasket off. I even took them apart a month or so ago to double check, and they were still at 10mm. I've been through the jet swapping, then I ordered new 55 idles and installed them, no change... plugs still come out black.

When I turn the idle mixture screw in, I hear the idle begin to slow down, then start popping, thats when I back it off slowly until it speeds up and runs smooth again, then I've been backing the screw off about a half a turn after that. It was still running rich, so I did the same thing, and instead of a half a turn back out, I backed it off about 1/8 of a turn and that was somewhat better. If I lean it out anymore than that, it starts to sputter. I'm about 1 1/4 turns from bottoming out into the seat.

I tried the slow pedal approach also. On acceleration, if I'm easy with it, it runs well, then it starts running kind of soggy... if I give the pedal a little jolt, it clears up and runs smooth again. Still getting popping on deacceleration, but not as bad as before I changed my pump. What am I doin wrong here?
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oo9less since 2007
-72 Ghia-

[John M.]

What heat range of plugs are you using?

[SkrapMetal]

[John M.]

I have the same engine combination as you do from Chico. Your jetting looks almost perfect from my trials. Which is why it doesn't make sense that your plugs are fouling so quickly. Unless you have some sort of ignition problem. What kind of timing are you running at the moment?

My engine backfires/pops lightly on deceleration too. I've just learned to live with it, since the engine is tuned to the best of my ability.

[SkrapMetal]

I believe it was a chinese 009 with a compufire, but I put in a German 009 (points) from my old 1600, and it ran better 30 at TDC. I'm gonna eventually get rid of it and get an 010 or a Mallory.
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oo9less since 2007
-72 Ghia-

[John M.]