Webber 44s - uneven suction?

So you get your snail and you warm the beast up and undo the linkage and go about setting the idle speed and balance and it all goes about as it should except all but one of the four throats come in at the same value, let's just say the flow number is 7, to within a line width. But one throat on one carb comes in at 5.5. I think I saw somewhere that this means the throttle plate on that throat is just a scoosh too closed and the reason is because the plate &/or the shaft to which it is connected was made wrong. I assume there is but the one shaft to carry both plates, and so there is no way to adjust the relative position/tilt of the throttle plates once on the shaft. (A) Is this the right diagnosis? (B) If so, can this be fixed? Or maybe a better question is: (C) Does it need to be fixed?

On my Weber DCNF carbs I have air by-pass screws that can be used to balance the air flow between throats. You probably have something like this too.

Kelly:

(A) Is this the right diagnosis? NO - it's NOT the throttle shaft

(B) If so, can this be fixed? Or maybe a better question is: (C) Does it need to be fixed? Not the problem that you described.

See Mike's post above, then go out and get Bob Thomlinson's book on how to live with your Weber carbs without hating them (CB Performance) and find the section on tuning, especially wrt air bypass adjustments. Setting the air bypass on that throat takes about a minute, tops, and you can dial it right in.

I love this forum!

I learn something new EVERYTIME I visit this site!

OK, can do. I have this book. One thing I think I read in there (been a while, will have to look again) is that the little air jet and lock nut thingy just about NEVER needs to be anything other than closed. Not sure where I heard that one. Anywho, I'll do my homework and fiddle w/ the rascal and see what happens. Of course the deal here would be that the one throat w/ the low flow will in fact gain flow by adjusting this jet outward. I believe all of the ones on my carbs are currently screwed down tight.

And PS: wrt how to live w/ these "fine and delicate instruments" and not hate them is a concept devoutly to be wished. I am not there yet. All these comments about Delortos (?) being sooooo nice are starting to get my attention.

PPS: I recently heard (source: Cory??) that some folks actually drill holes in the manifolds and connect the two inlets together w/ tubing (maybe route across the engine and communicate the pressure to all four throats??) to be sure the pressure is equalized for all. What does the brain trust here think about that idea?

I heard someone say "well, tuning Webers isn't rocket science" --- think that was Cory too!

I've plumbed all my webers together into a single reservoir and get my MAP pressure from it for my programmable ignition.

you can fine tune each barrel with what you talked about.

http://www.google.ca/search?hl=en&q=tuning+IDF+weber+carburetors&btnG=Search&meta=

Rocket Scientist Kelly:

I was gonna tell you what page to look on, but I can't find my book, here (it's probably up North) and I can't remember the location of the air bypass screws on a Weber, so start researching.

It is infinitely more difficult to "connect all the ports" on a dual-port engine than on a single-port version, so, therefore, only a hearty few have attempted it (with eh? results, too, I've heard). The best set-up I've used is a single Holley 2-barrel on an EMPI manifold, but it was all designed to work together. Merklin had one similar and he loved it.

Also, the way the Webers (and Dellortos, too, for that matter) are designed, they probably wouldn't like all of those additional power pulses coming back UP the manifold as the other cylinders are doing their thing and transmitting their business across the connector pipes.

MUCHO better would be to do two things: 1.) spring for a "Jet Doctor" horizontal discharge kit for your Webers from CB Performance. That should take care of 90% of the jet-clogging problems you might have. You'll still get one every so often, but, to be honest, I've only have two truly clogged jets in the past ten years. Not bad. I have never run my carbs without the horizontal discharge conversion, so I have nothing to compare, but they just go and go and go.....

Then, 2.) put some high-temp wheel bearing grease on the top and bottom rubber gaskets for your air cleaners to positively seal out any crud that might try to find it's way around the filter. You don't need a ton - just smear a small bead along the gasket and let it squish in as you put the filter in and lid on.

BTW: NEITHER of these tricks will keep water out if your engine cover doesn't have drain holes in the bottom of the inside wings. I guess that might be 3.), wouldn't it?

gn

Gordon, just to clarify, I think you are talking about two different things. Cb sells the "jet doctor" which raises the point under the air filter where idle air is drawn: http://www.cbperformance.com/catalog.asp?ProductID=1507

Then there is the "weber update kit" which changes the main jet discharge to a horizontal tube:http://www.cbperformance.com/catalog.asp?ProductID=508

The jet doctors are less than $20, the update kit is $140, and includes new accel. pump diaphragms and venturis and gaskets/O-rings.

Kelly, you can definitely open up one air bypass to bring the idle air up to snuff. I think it is a 7 or 8mm locknut, and then a stubby flat screwdriver to open it a bit. You should be able to adjust it while it is running with the snail in place. Make sure the snail is sealed real well, cause any air leak will cause it to read different in that cylinder. It is number one, isn't it, IIRC? This adjustment works for idle only, as soon as you crack the throttle air is no longer drawn through this orifice.

I agree with Gordon, if your air filters and bases are clean, and your fuel source is clean, the biggest problem is water in the carbs. You really need to address this on Speedsters, not an issue at all on Spyders. I like the smear of grease method, it works.

I would NOT make up a balance tube for a dual Weber setup. It is a waste of time, these things are not that hard to tune well, and then they should stay that way. All it would do is make it harder for you to set the individual idle mixtures/speeds, and MASK the problem, not solve it. The only exception to this is if you have EFI and a manifold air pressure(MAP) sensor. Otherwise, don't overcomplicate things. And fix your linkage to eliminate ALL play. Set it and forget it.

There is a slight possibility that your intake manifold gasket and/or carb-to-manifold gasket is leaking on that one cylinder slightly. You might want to check that out as I know you've had at least the right side carb off before.

The real solution to intake manifold leaks for me was Vanagon Waterboxer gaskets, port matched by hand cutting, Mr. Xacto knife is your friend. Use Loctite 517 anaerobic gasket maker on both sides, a very light smear on both sides of the gasket, along with their spray primer. You need thick steel washers on top of the manifold(one has to be ground into a D shape to fit), the 11mm STEEL manifold nuts(not brass), and thread locker. Or go like Gordon and go gasketless, I am not sure what he used there. DO NOT EVER use the CB gaskets, they are soft and will squish out and leak, guaranteed! Get the swivel thin-wall socket Gordon got, and torque them to 18-20 ft. lbs. Let them dry overnight, and say goodbye to manifold leaks.

K&N makes grease for the air cleaners. You can get it on Amazon.

I continue to be amazed how much Amazon has expanded beyond books.

Yes, I thought about a possible gasket leak and will double check that using the flamable squirt method. Meanwhile, I have torqued up the manifold nuts (not easy, as you say) but have not gone to steel nuts and washers yet. I'll try the air jet thing on the one throat, and see how that goes. I have applied thin grease at the airfilters, and am running w/ Al baking pan rain hats. I am pretty sure the snail is fit in there tight.

Still looking for just exactly the right tool to make R&R of the fwd idle jets a reasonable job vs the total PITA it is otherwise.

I looked at the Jet doctor thing that raises the air intake for the idle circuit up into the air filter space. Seems simple enough. The "horizontal tube" thing Gordon mentions is new to me -- will have to look more deeply into that.

Txs guys for the added info here -- all good stuff. Not sure when I'll get to fiddle w/ this -- after the Pumpkin Run II I guess.

Sometimes, propane, ether etc will only show a slight rise in RPM's if you have a vacuum leak.

Use Aerosol Carburetor Cleaner. If there is a leak, the engine will stumble and it is much easier to detect than a slight rise in RPM's.

Danny's right - I've been overcome by Senior Moments but spending blissful time in ambiguity.....

I have the horizontal discharge tube conversion on my Dels and I remember it costing about $140 or so. I've never run without it and I think it works very well indeed. As for the "Jet Doctors", nope, I don't have those so can't really comment on them good or bad. I DO smear the air filter ends with wheel bearing grease each time I remove them.

If you go gasketless on the intake-to-head manifold interface, then I used Locktite 510 per Jake's recommendation. Remove the carb from the manifold and then remove the manifold from the head. Get a sheet of glass and place a piece of 400 grit wet/dry sandpaper on the glass and then, using the glass/sandpaper as a surface plate, sand the bottom of the manifold so that the mating surface is flat. You should see after a few seconds where your high/low spots are, so keep on sanding until it all evens out. Be careful to keep the manifold flange flat against the glass/sandpaper. Once it's all the same texture, it's flat and you can clean it and re-assemble. I assumed that the head mating surface was flat because (a.) it's machined and (b.) it's impossible to get that surface flat without removing the heads, so I said "screw it". Read the Locktite 510 tube for coating/assembly instructions and you should be fine. It gels in the absence of air, so any excess that squishes out will slough off (eventually) and not hurt anything, plus you can run a slightly thicker film to fill in any potential voids on the head mating surface.

My biggest problem with my manifold gaskets was that my port openings are BIG, leaving very little mating surface between ports so the gasket center would get sucked to one side and leak between ports. VERY hard to find with a can of ether/etc., from the outside because the leak is on the inside. CB gaskets didn't last long and I finally went this route - OK so far.

Don't faint at the cost of the Locktite 510: A tube about the size of a toothpaste tube is $38, but it's GOOD STUFF!

wrt hand lapping on a flat, a machinist once showed me to do this using a broad figure "8" pattern vs. circular or back and forth. And yopu need a good flat, and pane of glass shopuld be the ticket. Keeps you from tending to emphasize one edge over another, so it seems. That said, there is little chance I'm going to jump right in and do this, believing I have OK gasket seals just now. But ya never know when a tear down like this may be needed. Still don't know what the horizontal tubes GN has are and what they do, but figure I'll find out one of these days . . .

Did you click on the link I posted above, Kelly?

Glad to hear your gasket suck problem is solved, Gordon. My ports are very large also, leaving about 3/32" of sealing area in some spots. Seams like either my or Gordon's method should work for all.

Kelly.....When and if you remove the carbs, lay a straight edge on each and every sealing surface. I chased a leak from a bolt hole that was slightly lower than the rest of the flange, and seemed ok to a casual glance....The figure 8 on a pane of 1/4 inch or thicker glass is the ticket for lapping parts at home....Hope you find the problem is nickle/dime......

Plate or float glass would be good. It is flatter than ordinary window glass.

Speaking of glass, it is actually a very thick liquid, not a solid.

Another thought on Kelly's low cylinder problem. If using carb cleaner or propane doesn't show a leak anywhere, then there is one thing left to do. That is swap the carbs left to right. Should be no big deal to move the fuel inlets and swap the linkages to the other end. Then see if the low "cylinder" migrates with the carb or stays where it was, at #1 cylinder. Then you'll know if it is cylinder or carb related.

Of course before I did ANY of that, I would first do a valve clearance adjustment/check, just to make sure.

Kelly, somebody with a Speedster has GOT to try this. You all have manifolds that put all the jets and adjustments on the outside, which is a royal PIA for all of you. CB Performance sells two types of manifolds, the regular and the space-saver. Now someone has to buy the space-saver and see if it fits with a standard shroud or not. You all have the regular type, which puts the adjustments on the outside. The space-saver manifold turns the carbs around so you can get to everything. Number 3169 is the regular and 3267 is the space-saver. I think the space-saver is a round port, because my manifolds are welded and ground out forming HUGE ports. I am sure that is what I have, I have my build sheet and have never seen any other carbs mounted like mine. Somebody will have to be the guinea pig on this.

Here's the link: http://www.cbperformance.com/catalog.asp?ProductID=532

Any takers? $70 for the pair to make your "Weber time" easier!

This is pretty random, but we've had carbs where they have backfired violently and slightly bent the throttle plate. If you are taking them off to switch sides, sure wouldn't hurt to take a look at that.

angela

If I suspected a weak cyl.,I'd do a compression/leak down check on that cyl. before pulling carbs.


~WB

Me too.

Well, I certainly have a lot of advice here. Next step after all of this will be a complete engine overhaul. Pull this, swap out that, get new manifolds, like it was something for a lazy Sunday afternoon. Hmmmm. I'll go one step at a time and let you know how it turns out. Gonna be a while, since leaving town this week for business and visits.

Half of an update: The balancing mentioned above was in prep for the Pumpkin Run II (which thread you can see in Events) and so I set out on that chilly Sat morn w/ the car as described above. There was some mild poping and coughing evident on the way out, and the engine was doing some "hunting" at even and modest throttle on level road. It was getting annoying running up the interstate to Alan's. But run up the road I did. And then I ran the PR II, sometimes hot exercising the sway bars and other stuff a bit more than normal. The whole trip was about 300 mi, I guess, +/-. Somewhere along the way I noticed that the engine was running a lot smoother. There were two gas stops along the way. I can't say what happened exactly, but whatever was still bugging the engine seems to have disappeared. I know: whatever is wrong, the root cause if Webers are attached always has to do w/ the idle jets, and so I guess one was a little out of sorts, and for no reason known to man, righted itself, and so is now running correctly.

PS: I have not re-checked the air flow in all four throats w/ my snail yet, but plan to do so soon. If still one is unbalanced relative to the others, will try to open the little air correction jet there, as described.

Motor popping, then runs better after a long run tells me that the carb(s) cleaned themselves out. ~Alan

OK, I went and looked at the horizontal jet kit from CB at around $140 or so. These are CB parts vs. something from Weber, I figure. anybody here have experience w/ this mod on Webers, 44s in particular? Gordo says he has 'em (or something like 'em) in his Dells, and says works fine. What I wonder is what does "works fine" mean? CB says all the usual marketing BS about more torque and more HP, but what else do you get out of this effort and expense? And how much extra ooomph? 2%?? How about more tractability? Mains coming on sooner? Later? Quicker response? The question is, who has done it for Webers and knows what the difference is and can tell about it? As far as I know the mains in my 44s "work fine" too. Only real problems w/ the arranngement in my car are the persnickety (?) idle jets, and how they can ruin a nice day for cruising now and then. I do not think this kit will have a thing to do w/ that problem. Who here knows the truth? Has this kit been around a while, or is it something pretty new?

Kelly:

The CB horizontal discharge tube kit (not jets - that's a different circuit and you use your original jets) has been around since at least 1997 (that's when I bought mine) and they have a lot of road time on different engines to prove them out. They work on the idle circuit only (it has no effect on the Main jet circuit). The biggest reason I bought this kit was to avoid idle circuit jet problems and I was apprehensive that the "Jet Doctor" kit would provide the same level of avoidance and optimal air flow into the velocity stacks.

What do I mean by, "Works Fine"?? Well, I've been running them since I first got Pearl on the road (1999) and have had exactly two incidents of clogged idle jets. One is for sure (it looked like a shredded Redwood log in one jet), and the other I'm not too sure of, but I'll count it anyway. I've gotten into the habit of greasing the air filter ends and I haven't had any trouble in years. The last time I had a clogged Idle jet was when I was still living in Tiverton, and we moved from there four years ago. I have way more dirt roads here in Beaufort (parts of it are like a third world country) and haven't had any problems here at all.

Performance-wise, people tell me that I've got a pretty stout engine - one of the quicker 2,110's around, whatever that means. I seem to have a LOT of mid-range torque, which comes on around 2K rpm and stays very strong up into the 6,500 range. Glorious power in the 4K - 6K range for the track, but LOADS of use-able torque in the 2K - 4,500 range for the street. Now, some of that comes from the Engle 120 cam, some from the Berg exhaust, some from a lightened flywheel, some from the 40mm Dells and some from the massaged intake manifolds (it's a holistic approach to engine design) but I'm sure that the horizontal discharge tubes help in there somewhere. All I know is that it leaves 1915's and a lot of 2,110's in the dust. A lot of the time, and the car weighs 2,000 lbs. Imagine what it might do if I dropped a couple of hundred pounds??

One problem I've had since day one is a very minor dead spot in the mid range that I've attributed to the lack-luster performance of Bosch 009 distributors and their Whusy advance curves. If I crank the advance up to 36 degrees at 3000 rpm the flat spot goes away, but then it pings on 89 octane gas, so I've backed it off. Everyone I know who has traded up to a Pertronics distributor has eliminated the dead spot (because Pertronics runs a more aggressive advance curve), so that's on my list of upcoming "must-haves".

I have not wheel dyno'd my car lately, and that would be moot for this exercise because I have no "before and after" data to offer. The latest data I have is with a "G-Tech" system and that was telling me 153hp - whatever that means coming form a G-Tech, although Chris has done both 4-wheel dynos and a G-Tech on his old Eclipse and the data comparisons were interestingly close (but I still don't know what to believe with a G-Tech. Can it be that easy/accurate to use??)

Anyway, lots of words and not a lot of additional data for you. If all you want to do is avoid clogged idle jets and yet minimize cost, then the "Jet Doctors" might be worth looking at. Just remember this: Moving the top of the velocity stack up close to the inside bottom of the air cleaner lid has to be carefully done to avoid restricting the intake flow and thereby "choking" the engine. There is a minimum gap needed between the stack and the bottom of the lid. It's mentioned in the Thomlinson manuals, but I can't remember what it is. Check it out and go from there.

Good luck, gn

gn,

Txs for the additional data. Frankly, I am more confused than ever now, since I thought this kit was for the main jets. Guess I can't read very well. The only way any mod could help the idle jet clogging issue would be if it eliminated that fitting w/ the too-small hole in it. I have pinged CB to provide more info, and I can do more research about the details -- I am a detail kind of guy. Also, I am just storing this info up against the day I may have to go into the carbs and redo stuff. Rigth now (as in today, and yesterday) the engine is running smooth, so jets must be clear for the moment. Whooopeeee!!

I looked on the CB site for info on the Jet Doctors, and lo and behold, I already have them. I guess even they can't stop everything. I guess I'll investigate Gordon's Discharge Tube (lots of possibilities there, Vince) kit.

I may be wrong, but I believe the horizontal discharge tube "update" kit has NOTHING to do with plugged idle jets, at least on Webers. It has to do with drivability and ultimate horsepower. If your car is running great, I wouldn't bother unless you REALLY want to get that last bit of performance.

On another note, I found a VERY good online article on Weber tuning:

http://www.carburetorclinic.com/tuning_the_weber_idf_carburetor.htm

And by the same guy on cleaning and initial setup: http://www.carburetorclinic.com/setup.htm

Lane, think hospital clean!


On the horizontal tubes, original article from Hot VWs:
http://www.cbperformance.com/Jan2000.asp

Thread on euro vw forum about CSP update kit, which is supposedly a modified CB kit:
http://www.volkszone.com/VZi/showthread.php?t=430117

Shoptalk forums short thread on CB update:
http://www.shoptalkforums.com/viewtopic.php?t=104107

The first one Danny lists is the best.
Mark Harney knows his shit and explains it very well. It's too bad he retired from the business.
Kelly, your carbs were never cleaned prior to install. If you haven't pulled them off and pulled them apart for a proper cleaning you will fight with them until you do.
You might think your engine is running well now, but once you get your Webers dialed in...:):):):)

Terry,

Well one of them has been R&Red and cleaned so far. During the early going in my "education" I got a deluge from an overnight rain storm that actually resulted in a hydrolocked cylinder, which experience also carried water and debris into the float chamber. great fun -- happend at Carlisle, so within three minutes of discovery, there were about a dozen able mechanics bent over the back end applying the fix. After pumping the water out of the cylinder, there was some idle jet cleaning done then that helped, but the whole thing was still hinky afterwards, so I pulled that carb and cleaned all. Things ran fine there for a while. Have had several in-situ jet cleanings since. It is a real PITA for a Speedster, but I am getting better at it. I have been advised to pull both carbs again, do a proper cleaning and checking, and especially gauge the jets to be sure they are: what they say, or what they should be for my motor, and are the same left to right. The builder swears this was all done initially, but you never know.

PS: Gordon's favorite fix (SeaFoam) has also been used and I can say has had beneficial effect.

I can add a saved link, if there's a need for more info, mainly exploded view. (Danny's links were good) What are the "specs" on the SeaFoam?

Sea Foam is a cylinder/piston fogger/lubricator most commonly used for Marine purposes, like when you put your boat to bed for the winter. I would pull each plug in turn and give each cylinder a blast for 2-4 seconds, replace the plugs and let it sit for the Winter. They also have a water dispersent in an aerosol can (I usually use WD-40 for that), a gas stabilizer (I use "Stabil" instead of the Sea Foam version) and a couple of forms of dry-gas, all with boaters in mind.

I have NOT used their dispersent and stabilizer products - all I've used is the cylinder fogger and thought that I did the job well. It is usually available at Boating supply stores and marinas and I just use it per the label. You can on-line order it from West Marine.

gn

Thank you for that explanation. Never owned a boat, but did help bro-in-law winterize a old wooden craft in San Diego area years ago. Forgot the names of all the supplies we used. Never had to winterize anything around the house here either; just doesn't get a sustained "hard" freeze for too long.

i had the same problem and it tuned out to be both manifolds were cracked. Took us a while to figure it out but Henry sent me new Manifolds asap!