Weber crisis of faith

[daniel911T]

Hey everyone,

The regulars should know well of my car's trials. The one sentence update: it starts, it times correctly, I can tune air flow on the carbs, but mixture seems to have no effect. Motor is a '70 2.2T with E cams.

Idle is ok, WOT is kinda rough, transition is full of surging and bucking. I just went through my dizzy, and the timing light says it's right on. I have an MSD, I just installed a set of magnecor wires (HUGE improvement), and I have a pair of Weber 40 IDA 3C1 carbs. Jetting is as recommended by Weber, should be right on for a 2.2 T or E.

I measured the shaft play on the Webers today:

I finally broke down and got a digital metric dial gauge. I just went out and measured my shaft play, here are the results:

Left carb (driver's side)
linkage end:
0.3mm vertical
0.2mm horizontal

Front end:
0.3mm horizontal and vertical

Right carb (passenger side)
linkage end:
0.2mm vertical
0.0 horizontal

front end:
0.2mm vertical
0.1mm horizontal

Can you please give me your opinion on these numbers?

I'm losing faith in my Webers. I'm strongly considering selling them and getting a set of solid Zeniths.

Comments? Thoughts?

Thanks!

Dan

[1QuickS]

Hi Dan,

I don't recall what was checked:

1-fuel pressure set to 3.5 psi at the carbs
2-float levels set using the vial gauge
3-accelerator squirters squirting evenly and about .6 - .7 ml

Assuming venturis are 32mm:
main jets 130-135
emulsion tubes F26
idles 55
air correction jets 170-180
and the above are untampered

Air correction jets in the top of the throttle body are clear from blockage (by gasket or by debris

Idle jets are clean (remove and see light thru their length)

Side-to-side air flow set to balance @ 3K RPM when working throttle from driver's seat (assistant)

I strongly suggest getting a Colortune tool to diagnose mixture settings while idling (takes the guesswork out for the uninitiated.) This is a good tool to have whether you run Zeniths, Solexes or Webers. The Colortune lets you SEE exactly what is going on in each cylinder when you make your idle adjustments; rich, lean, spark, etc. so you can diagnose bolcked fuel passages, erratic fuel delivery, ignition, sensitivity to screw twiddling, etc.) Also the STE synchrometer is what I have come to use.

I find that when in good condition even a small amount of idle setting variations manifest themselves through transition.

You might review your symptoms using my Trouble Shooting guide:
Weber Carbs Technical

By the way, initial setting for carb adjustments (how I do it):
1-throttles closed all the way and turn stop screw until first transition hole is just about to be unblocked by edge of butterfly (1 1/2 turns)
2-mixture screws 2 turns open
3-idle air correction screws 1 turn open (helps keep you from activating progression circuit early)
4-throttle linkages disconnected
5-balance and set mixtures at 900 RPM
6- set drop links to same length using calipers to measure
7-check cross bar to see that the 8mm ball studs are coplanar with the cross-bar axis
8-adjust 3000 RPM speed with cross bar and drop links connected and by adjusting one of the side brackets (loosen the securing nuts) on the intake manifolds to balance (not with drop links)

All that being said and done, worn throttle shaft bushings will cause issues such as yours but before you jump ship review your work carefully as Zeniths have their own demons.

Another litmus test regarding wear-out: When idling, can you hear the throttle shafts clicking and can you feel them moving up and down where the shafts exit the throttle bodies? Also, is there routine sniffing (cylinders 2 and 5 usually are good but the others are vulnerable to wear-out) through the intakes (lean) that enrichening the mixture screws doesn't fix? This is bad news. No amount of cleaning/tuning can overcome the erratic behavior of throttle shaft/bushing wear-out.

[jpnovak]

How long did they sit during the engine swap? Did you drain the gas from them prior to storage?

It sounds like you have clogged passages or even dirt from the fuel system. If you have no effect on the mixture screws then you have gunked webers independent of the jetting.

Tear them down and clean them out. I like carb cleaner followed with copious amounts of compressed air. If they are really dirty inside then consider a soak in an appropriate cleaning agent.

Once they are clean then you can go through the process of balance and adjustment. And yes, don't forget the fuel float adjustment and verification.

[Quickstep192]

I had similar issues with my webers last year. I'll admit, I'm jaded by the issues I read about on boating forums, but I think it's related to ethanol gas in cars that are allowed to sit for long periods of time. I thoroughly cleaned my carbs, got good results after the cleaning, then the problems cropped up again. After speculating that my older fuel lines were being dissolved by the ethanol gas, I replaced all the lines with alcohol rated marine grade hose. Another carb disassembly and clean and so far, so good. If I lost faith in Webers, I'd think the way to go would be toward PMO carbs rather than Zeniths.

[daniel911T]

Thanks for the quick replies! You guys are great.

I do have the PMO pressure control unit, set to 3.5. I have the PMO float gauge; they are all set right where they should be (between the top two lines). I do have an STE, and I can't imagine trying to tune without it. I plan on buying a colortune in the next week.

The carbs sat for about 5 years with gas in them. They were stripped down all the way, cleaned, and rebuilt with Pelican kits. I went to set the floats, and realized that the gas in my tank was way beyond gone. Drained tank, added a fuel filter right out of the tank, replaced the one right before the pump, and changed the ones right before each carb. Added a full tank of premium.
Fuel clean.

I then removed all the jets, progression hole covers, the bowl drains, and all the metering screws. All were allowed to soak in carb cleaner for a while. I sprayed an entire can of carb cleaner into the jet holes, metering screw holes, and thoroughly rinsed the bowls. I repeated this for the other side. That's a total of 2 cans of carb cleaner at pressure through the tiny passages.

On reassembly I had two o-rings break. One on a mixture screw, one on an idle jet holder. I had also found the air holes in my idle jets were squashed down to ovals. I drilled them back out. I also have two oddball mixture screws. I have already ordered a full set of o-rings, the right mixture screws, and some other incidental parts. I expect them to be here waiting for me with my colortune.

I put it all back together, and even with the noted discrepancies,tThe car ran a lot better. It even sounds totally normal and happy through the whole RPM range while sitting in the garage. The bad behavior comes only under load.

As I said, I can get the carbs to pull equal equally, and I can get all the holes to read the same with the STE. The issue is with mixture. I can turn the screws all the way in on several cylinders and there is no change. I can turn them out, and it starts popping, like it's going lean. That's the opposite of what should happen.

I'm sure the shaft looseness is a serious problem, but the cash to fix it is a bit too much for me at the moment. I thought I might be able to pick up a set of Zeniths with good shafts, rebuild, and be in much better shape than I am.


-Dan

[1QuickS]

Quickstep 192 is on target with the ethanol issues. I've had a couple of customers that suffered a goo like substance in the fuel bowls that cleaning rectified, these were problems independent of throttle shaft/bushing wear. Check out: Float bowl goo in Webers

[1QuickS]

When you sprayed your carbs down with cleaner were they on the bench or on the car? Did you take the top cover off to spray them? There is one fuel gallery which I refer to as "hidden" and is the vertical passageway between the emulsion tube well and the gallery that runs down the outside of the carb to the idle mixture screw. I discuss this gallery and how to isolate it for checking blockages:Webers won't behave. The remaining galleries are easy to verify for blockages. That thread has some other trouble shooting tech to consider as well.

[Greg Looseanus]

you still have blocked passages. soak em again and blow em out. Or have them hot-tanked.

[LJ851]

Current fuel is very hard on carbs , lots of acting up on the stuff i work on. especially if the vehicle sits for periods of time. May i recommend you invest in a wide band air fuel setup? You will not be disappointed.

[Bob Ashlock]

After some discussion with 1QuickS I, was encouraged to pull those lead plugs to gain full access to the idle paths. Lo and behold, even after all my cleaning with carb spray and compresed air, I still found considerable crud hiding in the passage associated with #1 cylinder that had been spittin' and poppin' like crazy during transition. In fact, on that one passage there appeared to be a little metal burr from the original machining process that was still attached to the passage bore and half blocking it. That created a snagging area for crap to accumulate over the years. Fixing this definitely improved things. Before I cleaned this out, I could not get the idle mixture screw to have any effect. Afterwards, much better.

[chris_seven]

I would almost certainly ulrasonically clean the bodies in a good cleaning fluid suitable for carbs at about 80 deg C.

Its amazing how much dirt you can get out of a carb that looks clean.

[daniel911T]

To anyone who lives in northern VA, MD, or DC: Do you know of somewhere that will do ultrasonic cleaning locally?

Also, does anybody know where you can get lead plugs?

General suggestions would be useful too.

Thanks all!

-Dan

[1QuickS]

I cast my own tapered lead plugs but I think most guys use either solder or split lead fishing weights. There was a lead shotgun shot for geese that worked nicely but it has been discontinued due to the spent lead falling into watersheds so now steel shot is used. Use a scribe to establish a center in the lead plug and drill with a 3/32" dia drill. Then take a self-tapping sheet metal screw and screw into the lead so you can get a grip on it to extract. Many times the lead plug will come out during the drilling. The earliest Webers used brass plugs in many locations in the throttle body and unless you are very skilled AND fearless I would recommend they stay installed. They require a slide hammer to extract once drilled through and they are around 8mm long.

[JP911]

Sediment from a decaying fuel tank gave me all kinds of fits with carbs (they were PMOs). Engine would idle fine and checked out OK when parked, but under load the crud would do two things: 1. slowly plug the filter at the tank which would cause starvation, and 2. would slowly allow small particles past both filters and into the carb passages. It was very frustrating to deal with. I found a good price on a reproduction fuel tank (new) and jumped on it. After a good cleaning of the carbs and filters + the new tank my issues were resolved.

Not necessarily saying this is what you're facing, but it's something to consider.

[daniel911T]

Hey everyone

Thanks for all your help! I have resolved all the non-shaft related issues with the carbs. Here's what I learned:

1. I replaced all of my mixture screws, springs, o-rings, and those special donut washers. I had a mixed bag of screws and springs from 3 different kinds of Webers. Now they are all the correct type, purchased new from PMO.

2. The tuning method we all are using is WRONG.

a. Paul Abbot's website, performance oriented, has the correct proceedure. The major difference is in setting the idle screws, the ones that move the whole linkage. The initial setting of just touching + 1/2 turn is a vital physical setting; it precisely positions the throttle plates so that they are just covering the bottom progression hole. You can set this cold.

b. If you are adjusting the idle with these screws, then the rest of the settings will be off because fuel is getting into the cylinder through the progression circuit without being metered through the sealed idle system. To put this simply, your mixture screws may work, but they won't work correctly.

c. The idle screw should be left alone! Paul recommends opening all the aux air screws 2 turns out, and the normal 2 turns on the mixture screws. Find the cylinder with the greatest airflow and close it's aux air screw all the way. (my method, not Paul's) Use this as your reference and adjust the others to match. If the idle is too low, open up your reference a touch and then match again. I found on the 2.2 that a 950 RPM corresponds to an STE airflow reading of 4.5-4.75, your results may vary. A good way to think of this: with the idle screws set, the cyl with the most airflow is your worst (leakiest), the one with the least airflow is your best (tightest). It's all about how much air is leaking around the throttle plate. ENGINE SHOULD BE AT OPERATING TEMP!

d. The mixture screws should be adjusted as normal. ON A WARM ENGINE!

e. The floats should be set so that the meniscus is ON the top line. If set between the lines it will go lean late in progression. I especially had a major flat spot between 4-5K rpm. Simply raising the float level to place the meniscus right on the top line completely fixed this issue. CHECK WITH ENGINE RUNNING AND WARM!

f. There is some discussion about fuel pressure. On my car, 3.5 is just right. SET WHEN ENGINE IS RUNNING AND WARM!

3. Not specifically Weber related... I performed a more presicse job of timing. I also thoroughly lubricated the advance mechanism in my distributor. I had been using a timing light with adjustable advance, when I switched to an old school, non adjustable, light the pictue got much more clear. Also, this time I adjusted it with a warm engine. Not sure if it makes a difference.

4. Probably the biggest single piece of the puzzle: I completely took apart and reset the entire throttle linkage all the way to the pedal. The setting was so far off that I was only getting to about half throttle, and occasionally the accelerator would stick! Once it even did it on the freeway. Thank god for brakes stronger than the engine and rev limiters! Now it's been fixed the pedal actually gets the throttle plates to go from full closed to full open, and it no longer sticks.

5. The Colortune tool is probably amazing on a car with good carbs. On my car it's worse than useless. If I set it to a nice blue flame at idle, it's lean everywhere else, basically, I couldn't get a useful result from it. On a car with tight carbs, it probably works great. The tool is extremely hard to install in a Porsche engine, and even harder to get out. When I think I'll get a useful result, I'll actually try tuning all 6 with it. As it is, I tried to tune two cylinders with it, and nearly went mad in the process.

In Conclusion:
The car runs great now!
It pops on trailing throttle due to the air leaks around the shafts, but under cruise or acceleration it is peppy, powerful, and extremely responsive! This was probably due to a holistic approach of looking at the whole engine management system: clean plugs, good wires, good timing and smooth advance, clean fuel, proper fuel pressure, clean carbs, and most importantly, a thorough understanding of how the Weber system is designed to work.

I want to throw a huge "THANK YOU" to Paul Abbot! You've been so helpful!

I have purchased a set of Zeniths that I am rebuilding and plan to use in the future. The Webers will be on the car for a bit longer as the Zeniths are in awful shape, however, when completed, they will have nice tight shafts.

Thanks everyone for your help!

-Dan

[kkinzli]

I think you will be really happy with the Zeniths. I am running them on mine and actually think they perform better than the Webers. I had Webers that my buddy lent me during my Zenith rebuild. I did have to go to a 55 idle jet and put in a fuel pressure regular once I had my Zeniths rebuilt. Al Kosmal is the Zenith expert. When I was doing mine I learned a ton from his threads

Cheers,
Kristoph

[daniel911T]

Thanks for the heads up on Al! I'll be sure to look him and his threads up.

I'm also taking pictures and notes as I work through the Zeniths, I'll post up a full "Anatomy of the Zenith Carbeurettor" in all it's gross detail as soon as I have a bit more.

I will admit that in many ways, I like the design of the Zeniths a lot better. I especially like the entire accelerator pump system a lot better, the roller on the linkage is more elegant than the Weber system.

I'm also planning a ball bearing mod for both the front and back of the shaft and the accelerator pump roller. I'll post all about it as it becomes more clear.

-Dan

[kodioneill]

I didn't read all the posts so forgive me if this was asked and answered. Does the car have a set of points? If so, check the condenser.

[daniel911T]

Originally Posted by kodioneill

I didn't read all the posts so forgive me if this was asked and answered. Does the car have a set of points? If so, check the condenser.

When I bought the car it did! It was supposed to have CDS, so the lack of that was a major contributor to poor running.

Now I have an MSD 6AL, Blaster SS Coil, and Pertronix Ignitor. My sparky sparky is quite healthy.

-Dan

[daniel911T]

Update!

The Webers were untunable in their state. Due to shaft leakage it was impossible to set idle mixture. It was a shame. I parted with them and sent them to a much better place: the tender mercy of Performance Oriented. Paul tells me that they were fixed back to perfect, and are now giving life to another lucky 911 out there somewhere. Happy trails old Webers!

I finally got my Zenith rebuild done, and once tuned in, they are absolutely stunning! I don't know if it is the difference between carbs that are good vs. carbs that are too tired, but the running is just shocking!

The idle on the Zeniths is a little bit burbly, but there is no hesitation when you mash the throttle, the engine response is instant and strong! It pulls smoothly from idle past redline without any dead spots. The rev limiter ends up cutting off the fun a lot of the time because the car is just pulling harder and harder all the way! There is still some fine tuning to be done, but... wow.

I've been living with the Zeniths for a couple of months, and I've driven a few thousand miles on them. They cruise great, accelerate and decelerate great, are extremely responsive, and respond predictably to tuning.

My impression at this point is that the Zeniths run way better than my old Webers ever did. I would love to compare them to a set of good Webers to get a fair comparison, but with my limited data, I like the Zeniths a whole lot better.

__________________________

Other news:
The Webers had been giving me hell for a long time, even on my old motor with the serious heart trouble. My old case # started with a 6105XXX and was a 911/07, which is a '70T motor. I checked and double checked the jets in the Webers, and they were the recommended jets for that motor, but it ran rich as hell all the time.

I solved that mystery today. I was tearing down my old longblock and I noticed that the heads were all cast in '68. That made me wonder.... When I finally got the heads off and measured a cylinder: 80mm. The motor was a '69 2.0T with a '70 2.2T case. The Webers were probably fine on the old motor... I just needed to jet them a lot leaner for the 2.0.

This would also explain why my present 2.2E(ish) motor feels like such a demon!

Anyway, this is probably the last word in this thread. I just thought it was worth letting everyone know that:

1. Zeniths on early cars, think 2.7 or less, run great!

2. If everything you've tried doesn't address the problem, disassemble and inspect. You may not be addressing the correct problem!

Thanks for reading!

-Dan