Another dumb Weber question.

lateapex911 · 09-04-2004, 07:00 PM

OK, my Webers have never run right. They came used. As it stood they did a lot of popping and such at idle. Tried much tuning etc, but no joy. Ran OK at big throttle openings though. I opened them up, found a semi collapsed float, and old O rings, so I ordered new parts plus a airflow gauge from Fast Freddies.

I got some new jets too. Originally the setup was: 180 air, 135 mains, and 65 idle, w/F26 tubes.

PMOs recommendation is 180, 145, 60 with F3 tubes.

The engine in question is a 2.7, with Solex cams running about 9.5compression. Ignition is Crane optical and MSD 6AL.

So, after a swap of parts, it now runs worse. Haven't even driven it, just getting it to idle is tough. And it won't take throttle.

So....the question is, why am I screwing my idle adjustments in almost all the way? They are running best at about half a turn or so. But the effect is odd, not distinct. (are 60s leaner than 65s? or am I confused?)

What am I missing?
I expected the opposite...

I've read many relevant threads here, (even printed tehm out and made a chart of everyones settings!) but of course, i have probably missed something so feel free to point me to one.

Thanks for your indulgement.

911pcars · 09-04-2004, 07:12 PM

Did you clean the throttle bodies before you installed the new parts? You have to make sure all passages are clear of crap if the carb is to work correctly.

Sherwood

Steve@Rennsport · 09-04-2004, 07:56 PM

Are the fuel inlet screens (at each banjo bolt) clean?

Do you have 3.5 psi of fuel pressure?

Are your float levels set PERFECTLY?

Are your accelerator pump volumes correct?

911pcars · 09-04-2004, 10:45 PM

Forgot to ask. How are the throttle shafts? Popping at idle sounds like air bypassing the shafts and causing a lean mixture.

"It won't take throttle" sounds like the accelerator pump isn't performing to spec. Do you see a squirt when you open the throttle (engine OFF)?

Sherwood

lateapex911 · 09-05-2004, 01:06 PM

some answers to your questions.

1-yes the bodies have been blown to an inch of ther lives!
2-yes, screens are clean
3-Ummm i dunno.

I will get my lab grade race car guage out (it needs 2.2psi!)
4-I don't have a guage for float level. The tech that sold and origianally did a quick set up of the carbs set them, and I have presumed them to be correct. I matched the new one o the existing one thru a trial and error tab bending technique. I have no specs tho, so I haven't measured, but I can use a micrometer. Is the a spec to look for?
5 Again, I don't have the little vial, but I have verified the squirt a good clean stream.

I will go get better answers right now.

Finally, one thing I saw when replacing the O rings on the idle mixture adjustment screws was that one bank had what I will call "spring landing washers" between the spring base and the O ring where it meets the body of the carb, the other side does not. Is this an issue!?

Also, is a 60 jet richer or leaner?

Thanks for the replies guys!.

Joeaksa · 01:30 PM

Jake,

You cannot presume that the float levels are correct. I did as well on a new set of carbs from PMO. They might have been correct when they were sent out but the wonderful APO overseas mail made sure that they were not right when I bolted them on.

A quick and dirty way to check is to pull the tops of the carbs off and see if all the fuel in the float bowls are at the same level. If so then at least they are even but my bet is that one or more will be off a bit. It does not take much to alter the mixture.

I made a float level gauge out of some common Home Depot items and it made a world of difference. Let me know if you want to see a picture of it.

That said, what Sherwood and Steve said are also VERY important. Popping at idle or initial acceleration are both symptoms of a lean mixture. Find out where and why its lean and proceed from there.

If the carbs are popping when you move the throttle then you need to confirm the acc pumps are working. Go to Walgreens or other drug store and get a insulin or other small hypodermic needle. Have them take the sharp off of it. Take a match or lighter and plug the small end. Hold it under the acc pump nozzle and pump the throttle once. Measure the amount of fuel using the gradiated marks on the hypo and do this with all six throttle bores and compare notes.

One last thing to watch out for is rust or debris in the fuel system. I lived in Germany and the car was a 1972 model that had been sitting for 9 months before I purchased it, and the fuel tank had not been filled. It had rusted a bit inside and I found out only after cleaning the Webers every week or so due to the rust flakes clogging the idle jets and causing not to idle. Make sure your filters are clean and in good shape and if you see any debris in the float bowls then add another filter to the input line or find the problem. Yours is a 1973 model so could have some of the same problems.

These carbs are wonderful but my knees are still sore from being on them for hours at a time learning how to work with them and I sold the car in 1983!

Joe

lateapex911 · 09-05-2004, 03:49 PM

good points, nice idea with the graduated cylinder!
I have taken the tops off, and they appear to be similar in levels, and the fuel is clean. I have a plastic RS tank in the car.

I will go back and get some hard numbers right now!

The carbs WERE popping, but since I put the 60 jets in, they are rich, no more popping. to me it is weird that the first set of jets were 65s, and i put thes in just because they were recommneded. I presumed that the smaller number was leaner.

The mixture screw are almost all the way in which strikes me as odd as well.

thanks

Raynald · 09-05-2004, 04:14 PM

hello Jake,
i have a set up like your for my engine i do some test for finding a good running engine and the idles jets of 65 is too rich i run with 60 and have no popping, is this possible of the auxiliary ventury is mounting in the wong way ?
Raynald

lateapex911 · 09-05-2004, 06:16 PM

Well, an update guys-

I went through the floats again, and measured them in their "as filled" locations, and tweaked one to match the rest. (The new float wasn't identical to the olds) I would love to find a spec for this.

After that I started with the baseline set up that PMO suggests, (for idle stop screw, air adjust screws, and idle mixture screws,) and it was way rich. The 65s had to be screwed in all the way, and still the exhaust stunk of fuel. Raynald, you are right, I tried the 60s and they still responded best screwed all or most of the way in. I then did the PMO suggested balance procedure with the air screws and it seems better.

But there is still the occasional pop from the inlets on the right. Mostly the center one I think. Adjusting the suspect barrels mixture didn't seem to help at sane settings.

So, why is this? I immediately think of a shaft issue. What is the best test method?

And while my tech set the motor up, and he's got a great rep, could a valve adjustment help here?

And sorry Steve, I need a fitting I ddin't have to test fuel pressure. I will get to it though!
So...what are the possibilities?

All in all, a big step forward. I do think the adjuatable arms need replacement..they are too sloppy.

Well, time for a test drive!

(I need to look up what an auxilary ventury is Raynald!..tThen I will check)

Steve@Rennsport · 09-05-2004, 06:25 PM

Hi Jake:

Please bear in mind that float level specs are based on a specific fuel pressure and that MUST be set before any float settings will be valid.

The floats must all be right on spec,....not just close,....

Raynald · 07:37 PM

Jake
Yes the pressure gas and float level must be perfect,
how much turns out do you have for your mixture screw on each bank ?
When poping in carb. do you try your mixture screws with 1/4 to 1/2 turn more out for to be more rich?
Ray

lateapex911 · 09-05-2004, 10:06 PM

Ok, back from the test drive. It is way better than it was before, but it still pops at steady and part throttle. Tip in is fair, and full throttle is rewarding, but I think could be crisper. That is probably jsut some jet experimentation.

I forgot to mention earlier (sorry!) that the carbs were outfitted with grosse jets instead of the usual needle and seat.

Will this affect the desired fuel pressure or float specs? Where can I get float specs?

Raynald, I did try to richen the mixture screws, but i will try again. They are nearly all teh way in. Maybe 1/2 turn out at most. Seems too far to me, but thats where it puled the best vacuum on my synchronizer.

(all adjustments have been made at about 80 degrees C on the guage)

RoninLB · 09-05-2004, 11:03 PM

Quote:

Originally posted by lateapex911

, I did try to richen the mixture screws, but i will try again. They are nearly all teh way in. Maybe 1/2 turn out at most. Seems too far to me, but thats where it puled the best vacuum on my synchronizer.

I would try setting mix screws at 1 1/2, 2, and 2 1/2 turns. Set air with air mix screws.

So your floats are not perfectly set with the engine running ?

Raynald · 09-06-2004, 06:14 AM

Hello !
I have 3 1/2 turns out for my mixture screws and my engine is running smooth !
and if I go to 3 turns it going to poping in carb ... with 60 idles jets
Raynald