What's this crud in my carbs???

Noticed a slight stumble when coming off the idle circuits. Figured the carbs might be a little out of sync, so I decided to go whole hog and blow out all the jets and carb passages also. I wiped down everything then blew out the passages, and to my suprise, there is a FINE black powder settling out of the gas dropplets. I have a filter at the tank, steel lines, and a filter between the pump and carbs.

The jets seemed clear, and synchronizing was no problem. The car now runs as befor, but that gunk disturbs me....Any ideas???

Might be deteriorating air hose, o-rings, or gaskets in the compressor. Did you use canned or supplied air to blow out the carbs? How old is the compressor and hose?

or, that black crud may be the diaphrams in the carbs falling apart due to the alcohol in the gas these days. I took a diaphram out of a 3 year old carb a few months ago and and about all that was left was fabric, the rubber was all black/brown bits stuck just about everywhere. Strangely enough it ran well other than idle jets kept clogging up...now how does it work (reasonably well) with the rubber gone?

Second the ethanol issue - it eats older rubber, o-rings, gaskets and removes crud (sludge, varnish) from your fuelines and gas tank --- moving it where you don't really want it. Supposely it attacks older non-zinc treated gas tanks too (and don't even think about a fiberglass gas tank -- boat issue mainly).

Air lines and hoses are PVC or Plastic....Looks like it just maybe rubber decay.....Oh well, something else to do... Thanks.

Could also be, Just plain carbon.. Have you had any spit backs up the intakes?

Leon, ya gotta stop eating those Varsity onion rings while you're working on the car.

sounds like carbon. Are you getting crappy fuel mileage? maybe you are running rich.

No backfires, running just rich enough to help cooling, carb throats clean.....Will pull accelerator pumps this weekend, and carb tops.....

are you sure you are running the proper jets?
what is idle like?
1000-2000rpm?
300 - up at full throttle?

Idle can be set as low as 350 rpm and still pull up through the power band....Normaly I run around 750-850 rpm....

idle at 350 RPM? must sound like a harley.

Do you have an A/F gauge?

i made one of these: http://autospeed.com/cms/article.html?&A=0217 and picked up a new BOSCHE oxygen sensor for $25cdn. it helps in tuning quite a bit.

Mango, where did you mount the sensor?

Did you order it from Australia?

This has got to be cheaper, less than $10, IIRC. A bargraph is really cheap compared to individual leds.

http://www.scirocco.org/tech/misc/afgauge/af.html

I already had a spare narrowband Bosch sensor. Actually I have one spare meter I built, if anyone needs it.

i ordered it from aust., but they have a distributor in usa, so it came really fast.

i bought a sensor bung and drilled a hole into my muffler side of my header. welded it up and painted it.

Would it be appropriate to place the sensor in the single pipe right after the 4 come together?

Sounds like a good spot, Mike. Just remember, a narrowband sensor may help with part throttle and idle tuning, but WOT will and should be out of range of a narrowband sensor to the rich side.

On the other hand, a wideband sensor such as an LM1 can show you the way to proper jetting.

FYI.....Accelerator diaphrams....fuel contact side just fabrick....New ones ordered...Thanks guys...

And the engine is smooth as silk at 350rpm.....

hmmm, precisely what I found too.... glad to hear it was something fairly simple...but still a real problem to troubleshoot. I only found it the first time as a result of a conversation with a friend. I have a huge diesel fuel filter and kept finding the black crud in the idle jets. After a few comments about "Weber" being Italian for "makes its own dirt" we tore a carb down and found the diaphram reduced to fabric....

Wonder how long the new one will last? I did the replacement on both carbs some time back....

FWIW, the Conoco/ Phillips and some BP stations around here offer 93 octane with no alcohol. Perhaps there are similar stations in your neck of the woods?

New parts are here....Holiday overhaul in works....

On a lighter side.....The wifes Camry spit out it's 3 yr. old battery, and I replaced it with Autozone's finest Duralast....5 days later a large puddle, about 1 cup, appears under the car. Checking everything reveals that the new battery has spit out about 2 cups of electrolyte. A quick check with the meter shows the alternator cranking out 14.1 VDC. ( high, but not ridiculous). Returned the battery, and got another from a supplier I've known for a looong time.
The cost was half that of the Duralast with greater crank amp cap.

After cleaning up the MESS where the acid had been thrown around the engine compartment. I installed the newest battery and the alternator was putting out 13.7 VDC.

Camrys have a drain in the catch tray under the battery, but it has no hose to route the acid out of the engine compartment....

More Fun, More Games......Any thoughts on the failure????

Just got to thinking . . . that might be MY crud in your carburetors; I went looking for some crud just this afternoon and I wasn't where I usually keep it. Couldn't find it anywhere.

Well folks - if nothing else, he IS consistent . . .

F.P. Sorry if I made off with your CRUD....I didn't think you would miss it as WEBERS kepp everyone well supplied... ;-)