Need help in resolving carb problem with dual webers

1. Clean the jets in that carb again.  The idle mixture screw should not be all the way in and should have some affect on idle when turned in and out.  If it does not, something in the idle circuit is clogged with crud.  Tis is a pretty common condition and one that is usually cured by an "open it up and go through it" cleaning.  Lane Anderson has become a pro at this with his '44's.

2. While you have the jets out, remove the mixture screw (be careful - some of those screws have teeny-tiny o-rings that have to be removed when the screw is removed) and blow some compressed air into the idle mixture screw hole.  20-30 psi should be fine.  Don't put your head over the carb when doing this as it tends to blow everything straight up into your face.

3.  Remove the carb top cover and check the float level.  If you don't have the specs on how to do it, check back here and I'll help.  For that matter, many of these builders just pull the carbs out of the box and install them without ever setting them up.  You should go through BOTH of those '44's and make sure they are both adjusted and set to spec BEFORE running them for real.  If you don't have Bob Thomlinson's book on Weber carbs, get it.  It'll save you a lot of grief in the future.

4.  This could also be caused by a leaking intake manifold-to-head or manifold-to-carb gasket.  That can be found by spraying carb cleaner (use the little spray tube) around the base of the intake manifold and carb when the engine is running to see if the idle changes (faster or slower) while the spray is present.  This is a longer shot than 1-3, but shouldn't be ignored.

Good luck,  The Speedstah Guy from Grafton

One more thing.......what size engine is this, and does it have "big valve" heads (like 044's or something)??

Thanks.

I feel for you, my friend.  I have battled occasional misbehavior from my 44IDFs for years.  Gordon's advice is spot on, particularly the bit about the float level.

FWIW - you might also check your accelerator pumps for proper activation and fuel dispensing.

I'm just saying...

Thank you for the information. I have blown air through the mixture jets and still no change. I do not see any change when I spray the carb cleaner around both ends of the manifold. However, I did notice when I was balancing the carbs with the air syncronizer tool that the left carb when facing the engine is a smaller barrel size than the right side carb. The side that will not adjust has the larger barrels. Is this a possible issue. Not sure if one carb is an idf40 and the other is an idf44. Does the 40 and 44 correlate to the barrel diameter?

Renfrance

Good point.  The ethanol in today's fuel dissolved the diaphragms after a while.

The carbs MUST be the same model / size....   If not, you're fighting a loosing battle....  I can't see Gene Berg sending an engine out configured this way....  Make absolutely sure they are both either IDF 40s or IDF 44s....

This was a CMC car factory built in 83 so the previous owners may have changed one of the carbs. Definately the left carb has a smaller bore where the stacks would fit on than the right carb. Could both still be 44IDF's and have a different size airhorn?

Forgot one thing. Which would you suggest if I change carbs? IDF40's or idf44's.

Renfrance

I checked the information provided by the previous owner. It states a Gene Berg 130 hp Brazilian AS41 engine case counter weightedforged crank 69.00 mm, Gene Berg connecting rodsCIMA/Mahle pistons rings and cylinders 90.5 mmtotal seal second piston ring, chrome moly steel pushrods, solid rocker shaft kit, swivel foot valve adjusters, lightened 200 mm  doweled flywheel, duaul weber 40 IDF carbs with GB linkage, Gene Berg 300 high performance cam with ported/polished cylinder heads with dual valve springs, fully balanced pistons rodscrank flywheel, Gene Berg crankcase breather, Monza 4 tip exhaust with J tubes, 009 distributor with compufire solid state ignition, GB oilpump with spin off filter and GB fuel regulator.

This is all I know about the engine. Perhaps this may help.

Thank you,

Renfrance

I checked the information provided by the previous owner. It states a Gene Berg 130 hp Brazilian AS41 engine case counter weightedforged crank 69.00 mm, Gene Berg connecting rodsCIMA/Mahle pistons rings and cylinders 90.5 mmtotal seal second piston ring, chrome moly steel pushrods, solid rocker shaft kit, swivel foot valve adjusters, lightened 200 mm  doweled flywheel, duaul weber 40 IDF carbs with GB linkage, Gene Berg 300 high performance cam with ported/polished cylinder heads with dual valve springs, fully balanced pistons rodscrank flywheel, Gene Berg crankcase breather, Monza 4 tip exhaust with J tubes, 009 distributor with compufire solid state ignition, GB oilpump with spin off filter and GB fuel regulator.

Renfrance

My mistake. I found out in the information sheet provided by the previous owner the carbs are Weber 40IDF's. However, one of the carbs has a larger air horn than the other carb. Any idea why?

Renfrance

I suppose it's possible someone put different horns on one side. The carbs should have 40 IDF or 44 IDF stamped somewhere into the edge of the lower mounting flange. Otherwise, you can measure the carb throat (not venturi) diameter.

The "air horn" (aka velocity stack) could just be a different size because that's what they had and they thought no one would notice.  It might affect the balance as you would get different velocities of air flow.  I doubt that it's your problem, though.  If the throats down in the carbs are the same size, that's more important.

The symptoms you describe sure sound like what I've experience intermittently lately.  I still believe I'm getting occasional clogs that work their ways through.  I may order some replacement accelerator pump diaphragms just to be safe.  Like you, I have yet to actually see a clog.  I have had the best results lately by making sure the floats are correct at upper and lower limits, and that the inlet valves are clear.  'tis a puzzlement.

Thank you for the information. I have blown air through the mixture jets and still no change.

You MUST blow thru the jet passages per Gordon's advice.

Yeah, make sure you have everything CLEAN and all o-rings, springs, etc. Float height should be 11mm without gasket, 10mm including gasket, 25mm on the drop. CRUCIAL to get both sides the same. It is possible that one idle screw is broken or a seat is damaged. If so, it must be sent out to have the seat fixed. Really you must take the tops off and clean the bowls, accel pump, and all passages. Then reset everything, and only sync the carbs when the engine is fully warmed up. Get the Tomlinson book, and go to Harney's carb clinic on the web. Really good info there.

http://www.carburetorclinic.com/

44 IDFs call for 10mm with gasket in up position and 32.5 in dropped, again with gasket per the Tomlinson book.

40's Lane

The drop measurement is not as critical as the "cutoff" anyway. Believe me, the gas is flowing back in plenty fast at my setting. Harney recommends 25 and that's where mine are. It is more important to get them exactly the same I think, the way mine runs speaks for itself. All sizes of  IDFs should be set the same way.....

Thanks for the reply. I have searched for the Tomlison book to buy online and no luck. Any idea where I can buy a copy?

sincerely,

Renfrance

 I went through the exact scenario last week with my 2017 and finally today i dialed it...

I did all the cleaning, float setting etc.

 what size are your idle jets? 

Mine stumbled if I went too small on the  idle/low end circuit jets. Started with 45's then 50's. Both were not clean at all off the bottom..then 55's which were better.. barely stumbled...and finally 60's. Those were nice through the lower range..however a bit rich on the A/F meter so 'reamed some 55's to 57 and now it's close to a spot on mixture....and the best that webers could be.

What I'd give for a set of Del's..sigh

Renfrance,

Book:

http://www.cbperformance.com/catalog.asp?ProductID=4 

Hey Ren, what Mike said above. It is a good book, but like I said, Harney is a great reference. I would say read the pages online, try to work it out. The Webers are really simple, once you tinker with them a little.

Today I went for a ride with my daughter, and midway through, plugged an idle jet. Hasn't happened in quite a while. Anyway, leave it running, pop the hood, and start closing the idle mixture screws. The one that doesn't drop the rpms is the one....back on the road in less than 5 minutes. Some big white chunk of crap(white crap=moisture) was plugging the jet. I really believe it is the ethanol in the gas, as the car was sitting for a couple weeks prior to this. I would say you almost want to put Stabil in with every tank...

Other than very occasional plugged idle jets, I'll take the Pepsi challenge with any Dell powered car.

I have finally given in and am now using alcohol-fighting Stabil with every tankful on both the speedster as well as the wife's 1998 Honda.  It's amazing how Congress caved in to the corn growers and pushed this alcohol-in-our-gas upon us, only to have it cost us all MUCH more in now-needed repairs and additional additives to fight the stuff that shouldn't be in our gas in the first place.

Mine are back to their misbehaving ways that were the norm just prior to the trip to the mountains.  I'm tired of tweaking them and will ignore them for this weekend.  I may order a rebuild kit and disassemble/blow out/rebuild them to see if that helps.  What are my chances of doing that without messing up the mixture adjustment that Danny put on them a couple of Carlisles back?

Lane---sorry you are still fighting the Webers.  I'd suggest a pair of Dells--they will change your life---ask Gordon.

I haven't touched my Dells in 12,500 and was always tweaking the Webers before.  Maybe someone here can offer you a deal?

Lane, The adjustments will be "out the window"....  That said, Danny can walk / talk you through the procedure....   If you need to borrow a snail, mines available....Or for a more than nominal "fee", (beeer, seeeea foood, etc.) I'll pull a weekender and help set them up...  Pay no attention to the two mechanics to the left.....

I have a snail, but far be it from me to discourage you and the lovely Miss Margaret from coming to the coast.

Jack - The Dells are a good long range solution, but not in the budget right now.  I do intend to contact Art Thraen and get some price info - that is, assuming I don't sell the car first.

Lane---I don't imagine that you would recoup the price of Dells when you sell but if you are hanging on to your Beck (Most of us vote "KEEP IT"!!!) the enjoyment factor may be worth it.

Good luck whichever way you decide!

Lane, call me. It can't be that bad. I know there isn't any money in the toy fund for carbs. Webers can be low maintenance just like Dells. Don't let the naysayers sway you!

I agree with Danny about the Webers.  If they're set up right (and that should cost under $50 from CB), you understand what's going on with them (actually, not all "problems" with Webers can be attributed to the jets), understand how to service them if they seem "sick"  and don't mess with them once they're tuned in, I believe that they are just as reliable as Dells or anything else, except, maybe, a small, single throat Holley.

When I had my Healey, lots of people said exactly the same things about SU, oil-damped carbs; jets clog up, oil dampener didn't work right, things leaked, etc, etc......   I rebuilt and set up a pair of those once, tweaked them for about 30 minutes and never touched them again for five years until I sold the car. 

They were just perfect for quite a while after Danny dialed them in.  Over time it is as if the fuel system has been infiltrated by schmutz that is now intermittently clogging some of those tiny passages in the carbs.  I could have gotten some bad gas, but I changed both fuel filters with no improvement.

Hmmm...  I wonder if the breather setup I have is allowing some foreign matter to get into the carbs.  It is connected to each air filter inside the filter.  There must be a source of contamination from somewhere.

I think I can eliminate the ignition system, as the car seems to run fine on the mains, just not on the idle jets - which is most of the time around town.

Danny - I will call you when I have ordered and installed the rebuild kits.  I have learned how to balance them and set the idle, but I am not so confident on adjusting the mixture.

There are usually a LOT of differing opinions on how to set the mixture screws, but this is how I was taught:

For the following adjustments go 1/4 turn at a time giving the engine about 15 seconds between each adjustment to react to the new setting.

I usually start out at a baseline from the following:  Slowly and gently screw the mixture screw in until you feel it bottom out.  Do not force it, as you might damage the needle or seat.  Once it has bottomed, turn it back out 1-1/2 turns as the base to start at.  Do this for all four mixture screws before proceeding below.

Start the engine and run for 15 minutes or so to warm it up.

From that baseline above, start screwing one screw out (richer) 1/4 turn at a time til the engine starts to stumble from being too rich. Then, counting the number of turns you make, screw the screw back in 1/4 turn at a time (leaner) until the engine speeds up slightly or dies from being too lean. Stop there and remember how many 1/4 turns you just made.  Now screw the screw back out half the number of 1/4 turns you just screwed it in.  For example if you screwed it in 8, 1/4 turns you would screw it back out 4, 1/4 turns.  It should be very close to being right.  Repeat this for all four mixture screws and you should be done.

I usually (at least on my own car) note how many 1/4 turns I ended up at, out from a too-lean position and what that was versus bottomed out and write it down somewhere in my tool bag.  Then, if I want to make it slightly leaner or richer I can turn it in/out 1/4 turn at a time and still make them all match, OR return them all to where I started later on.  I don't get into altitude changes enough to warrant changing jets so the above will suffice.

Just remember to be patient - you're looking for very subtle changes in how the engine is running at idle so, don't rush it - watch (and listen) carefully.

Just got home from "Carbs and Carbs" (carburetors and carbohydrates) that takes place every few months an the Italian restaurant owned by the son of one of my Cars & Coffee friends.  One of our core group is a fellow with several very nice cars including a '67 (I think) Aston Martin DB6 with three Weber side drafts.  We, along with some of our local Tour de Lemons guys (Fiat 124 Spider with olive oil cans for certain body parts), discussed my worsening problems.  He's thinking that one of the inlet valves may be sticking, which makes sense when you consider how I temporarily resolved the issue before the trip to the mountains.  He also had at one time replaced his original Webers with new Spanish-made ones like mine.  He never could get the car to run right and wound up rebuilding the originals.  Yet another argument for Dells, but I'll try the rebuild first.

Well, I hope you can get to the bottom of it, because I'm not coming back down there.  I'm officially reverting back to a full-fledged Yankee and getting involved with the LeMons folks up here.  Maybe we can field Saab 99 Turbo - II!

Ok Lane, standing by. I have Spanish Webers too. They are just as good as the Italian ones, and far superior to the Empis.

Did you get my Weber instructions? Scroll down a bit, they are on this page, along with a bunch of other great info: http://www.spyderclub.com/viewforum.php?f=19

I also warm my cold-blooded engine up for at least 15 minutes. A short, spirited drive usually does it for me.   

I'll print them off and use them after I've done the rebuild.  Thanks.

You can still give me a call if you need some moral support, Lane!