Weber IDF / Dellorto DRLA Troubleshooting
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- Опубліковано 26 кві 2016
- Finding a mid-range constant stumble. Weber and Dellorto dual throat carbs are very similar in design and operation. In this case these carbs were running great and suddenly started acting up on a road trip.
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I've learned a lot from your dellorto carb videos. Thanks for sharing your knowledge from years of tinkering with these!
+Tim Gingerich Bleeding, cursing, grinding my teeth, ( my dentist loves them ) night mares...... But when there On! Life is Good. :-)
Nice job GZ, those are some very versatile carbs for many applications .
+Rusty “rustyglovebox” Glovebox Your right about that. Everything from Harley's to Small block Ford V8's. Not to mention the lowly VW. Working sweet again though.
...It always works perfect when your done... Thanks for the video!
+vw64manyrd yeah,.... but then you wake up! LOL
Love my Dellortos , probably my favorite carb. One cylinder does pop at warm up . Assuming plugged idle jet. It's nice you can remove them from the top! Had to install 30 mm venturis to run on my motor .
+Stevie C. Sweet. Had mine over 20 years.
as always great info
+DriveShaft Drew :-)
Thanx for the video, always good info. I noticed you didnt use any sealent around the base of your carb(where the stacks are) where the air cleaner housing goes.we use a enclosed housing, not just a straight air filter. just curious?
Thanks for the vid!
You bet!
I got a question. I got a 1904cc with 90.5 cylinder heads, dual valve springs. Engle 120 cam, 40 idf carbs with the stock set up. 135main jet. I’m having huge problems. I was told I need to go down a jet size because it’s running super rich. It puffs black smoke, spark plugs are black. But yesterday the carb backfired and caught on fire. (Usually a lean mixture problem) anyone have any advice? I’m at sea level. I tried using a fuel regulator too. No luck
So I have a new set of hpmx's and i dont get a squirt (accelerator pump) on the first pump ,it falls on its face , if you let off give it another pump it shoots fine
Check the spring under the accelerator pump diaphragm. Also remove the check valve in the bottom of the float bowl and make sure the ball inside is working properly
Great videos EZ! I have a single weber 40 and your videos have helped tremendously. I have a four into one exhaust that I'm redoing and when I took off the collector, just for a goof I checked the exhaust pressures out of each individual pipe. #1 is significantly lower at idle, but picks up the pressure and they all match when I get rpms above around 2k. Is that normal? I have a .006 on all valves with 1.2 SCAT ratio rockers. Thanks much. D-man
That's an interesting observation...... I suppose if it doesn't sound right or run correctly I would do a compression test on all 4 cylinders and see how it compares. Also, and maybe first I would take my carb synchronizer (flow meter) tool and see if it matches the #2 cylinder. Sometimes the throttle shaft isn't perfectly straight or gets twisted a tad. That's when I use the tiny air bypass screw at the base of each cylinder to even things out. If you have a laser temp gun and it shows a lower temp at approx. the same distance from head on that cylinder it would indicate the same thing. Or a clogged idle jet. Just play around with it and watch all my IDF carb vids and you should be able to figure something out. I'm surprised your not getting the popping and snapping that typically comes with a lean condition???? Let me know what you end up with?
Compression roughly 120 all around. Spark good each plug. It was running rough after a tune up and before I realized it was my valves and not my carb despite my mechanic saying my "valves were good", I blew my muffler messing with the mixture screws. Yeah, probably my poor technique adjusting them with too much RPM but it wouldn't idle running at standard 1.5 turns out and the idle screw .75 turn past contact. After the muffler blew I spent a few days on your videos. On your valve gapping video you mentioned your gaps being a little off made you think it was a carb sputtering issue. When I checked them, they were all totally shut except #3. Old owner said he liked his gaps at around .001 to .003 due to chromoly push rods and less noise. I set them all at .006 and runs 10X better. Sorry for the dissertation, but is it possible my blown muffler caused enough pressure to get back into the engine to twist the throttle shaft? Pretty sure it helped close the gaps. Also think the mechanic who jetted the carb for me has the thing over jetted. Gas mileage was ridiculously bad. It does take forever to get to operating temp (my external cooler w/fan and extra oil sump). He replaced the accelerator pump, drilled out my .070 idol jets to .075 mm and went with F7 emulsion tubes (not sure what was in there before). Engine is 1915. I'm surprised he increased the jets since he set the mixture screws two full turns out. Also, how do you use the air bypass screws to make #2 different from #1 when you run single carb?
@@F18Dman My apology I did not retain the important fact your running a single carb. Let's start over.
I have no explenation why one cylinder would not exhaust as much air as the others... all things being equal.
I feel your pain my friend. It is not uncommon for someone to inherit problems from the previous owner even though he swears up and down it was running perfect until just recently.
The biggest problem is intake manifold heat when outdoor temps are below 70 degrees and the humidity is high. The fuel comes out of suspension and raw fuel doesn't burn. Most folks keep increasing the jet size to compensate. If your carb base is cold and frosting with ice it will not operate correctly at Idle speeds.
Single IDF carbs became famous and popular in desert race cars that are "Racing" across the desert and those engines usually have high compression and race fuel.
The second most common problem is flat sport or "Bog" off idle.
This is from trying to use the throttle plate screw to adjust idle. I will copy and paste something from Redline Weber to try and guide you.
Before I forget. IMHO muffler backfires will not typically harm your carb linkage. Also, many people try to take one carb from dual carb set up and expect it to work as a single carb. Thinking that eliminating dual carb linkage will make life easier. Another issue is the spark advance curve must be correct for your engine build. Camshaft duration can influence this set up.
Very few people ever get a single IDF carb to run well in all conditions and get decent fuel MPG.
IDF Weber carbs were orginaly made to be used on smaller displacement cylinders as a Port on Port design. All this info is in the Weber Book. But most folks just want a quick simple answer to there question.
IDF Carburetors
Low Speed Circuit Tuning
It is most important to verify all linkage and levers are installed without binding and the linkage opens to full throttle and is allowed to close to the Idle Speed Screw. This is the number one and two reasons for tuning errors, improper linkage installations and over tightened linkage nut, causing binding in the linkage assembly.
The Individual Runner carbs, IDF, have individual Idle jets and mixture screws for each barrel. They also have an additional air bleed screws and lock nuts. This is not used for idle adjustment or idle quality. The settings for these screws should be closed.
Standard IDF Settings:
Speed screw ¼ to ½ turn in after contact with lever maximum.
Mixture Screw 1 turn out from lightly seated.
“Lean Best Idle” Procedures
After confirming the linkage allows the throttle lever to seat against the Idle Speed Screw. Back off the Idle Speed Screw, then turn the screw in until it contacts the throttle lever and turn it in ½ turn. Turn in the Mixture Screw in until it “LIGHTLY” seats, then back it out 1 full turn. Loosen the 8mm wrench size nuts on the “air bleed” screws, turn in the air screws until it seats then tighten the nut.
a. Start the engine, it will run slow and like a tractor. As long as it will stay running, the idle speed is not important at this point.
b. First, turn in the mixture screw until the engine runs worse, then back out the screw ¼ turn at a time. The engine should start to smooth out. Continue to back the screw out ¼ turn at a time until the screw does nothing or runs worse. Then turn it back in to the point where it ran best. You want to tune the engine by sound. Adjust each mixture screw to the best, fastest and smoothest running point. Do this procedure with each mixture screw.
c. Now you may adjust the Idle Speed Screw. It should be sensitive and only require ¼ turn in or out to achieve the idle speed you like.
d. These carbs are commonly used in pairs, this makes the synchronization important, be sure to bring the high flowing carb down to the low flow carb. Then bring them both up to “proper” Idle speed. The Idle Speed Screws are not opened more than ½ turn in.
e. After synchronizing multiple carbs, reconfirm steps b. c. & d.
“Simple Rules for Calibration”
If your mixture screw is out more than one turn like 11/2 turns then your idle jet is too lean, go up one half size on the Idle jet.
If you mixture screw is not out one full turn, something like only 1/2 turn out from seated then your Idle jet is too rich, go down one half size on the idle jet.
This is all based on the important fact that your speed screws are not open more than ½ turn if they are then that is also an indication that you have a lean Idle circuit. You are cheating by opening the throttle plates and exposing additional progression holes in the transition.
Pump By-pass Valve:
The pump by-pass valve is designed to allow fuel into the pump circuit and when depressed, by-pass a percentage (hole on the side of the valve) of the fuel delivered to the accelerator pump nozzle/jets. We have included the zero by-pass valve in our jet kit. This will deliver all of the available fuel to the engine and not by-pass fuel back to the fuel bowl. This will increase the duration and volume of the pump shot with the original pump jets. To decrease the duration and increase the fuel volume we have included in our jet kit the larger 55 pump nozzle/jets. This is for maximum fuel delivery from the accelerator pump circuit. The accelerator pump by-pass valve is located in the bottom of the fuel bowl, one is required per carburetor.
More Tuning & Adjustment
1. Most Critical! Be sure for initial carburetor set up all air by-pass screws should be in closed position. These are not commonly used in standard carburetor adjustment.
2. Set the idle speed screw at ¼ to ½ turn in after contact with throttle lever. When doing multiple carburetors all linkage should be disconnected. All carbs should be bench adjusted to same setting.
3. Set the idle mixture screw to one turn out form lightly seated. When checking the seated position to make only light contact with seat, aggressive seating will damage needle and seat of carburetor,
Adjustment if possible should be to find smoothest idle with each mixture screw on all carburetors. Some prefer to do one barrel of each carburetor then come back and do the second barrel
4. Start engine as long as engine starts and runs do not turn up idle speed first.
5. After preliminary lean best setting of idle. Check carburetors for synchronization. Commonly done by checking lead or front barrel of each carburetor.
6. You will always want to bring high flow carburetor down to match the low flow carburetor. If this cannot be done you will need to recheck bench assembly for binding throttle in high flow carb. Once you have matched both carburetors you will need to set the idle to the desired idle speed setting. This will be done by adjusting both carbs up or down the same amount and re checking for synchronization.
7. Make one last check of lean best (smoothest running position) idle on all mixture screws one last time.
8. Best idle should end up with the mixture screws at or near one turn off seat. Check rule of thumb for idle jet selection on the other side of this page.
REDLINE
1225 W. Imperial Hwy Brea, CA 92821
1-877-405-4345
REDLINE is a division of WORLDPAC
The REDLINE Difference
www.REDLINEWEBER.com e-mail redline@redlineweber.com
Hi Ez, thanks so much for the Dellorto videos, really helpful :) can I ask: Does it matter if fuel is fed into the bottom or top of the banjo on the first carb?
On my left hand dell I have the fuel going into the bottom of the banjo and out of the top then onto the other carb.
Is that ok?
Thanks
You will be fine. There is just a screen inside that fitting on both carbs. Thanks for watching
Thanks :)
hey ez! love the vids
i have 36mm dellortos
a constant fuel drip in the number 1 barrel(forward left side)eventually washed out the valve seat on the 2litre ...???
The infamous Delloroto Drip. I never did figure out exactly where that lead plug is they refer too. I wish EMPI would have done a better job on those Super "D" carbs. EMPI always gets so close but seems to fall short.
Hey Ez: thanks for all of the videos and great info. I'm running a 1776 (in the process of rebuilding top-end) and it has the following: 69mm stroke, Gene Berge balanced crank, 90.5 cyma pistons, ported heads with .40mm inlet and 35.5mm exhaust, and Cam Engle W-110. Question, I'm running Dual Weber 44 IDFs, which i believe to be over carbed for the application but would like to try and dial in anyway. Can you recommend jetting for this setup or where you'd start? Currently I'm running 50's and 135 main. Cheers.
Jetting isn't the issue as much as to large of venturi's. Your describing more of a racing set up than a daily driver. Save those 44's for a 2110 or larger. 30mm venturi's work real well for 1776 but it will cost a lot to convert
Thanks!
Cool
+wtbm123 :-)
I'm having fuel pressure problems. I'm going to put all new lines on my 73 Super. Just want your opinion, would you use an electric pump and regulator. Or use stock pump and a pressure regulator. Thanks !
I'm tired of stock Chinese fuel pumps. I have been using electric for years without problem. Must use a regulator after the pump and keep pressure below 3PSI follow all directions that come with new pump.
@@TheEZGZ Thanks !
EzGz, I need you!!! 48 ida 60idles 150 main 200airs 37mm chokes Empi carbs. 5520 Msd with adjustable spring dizzy. Ok, whew! My problem is a stumble under load on my 2054 betweeen 2800-3000rpm. Which is my cruising speed. Floats checked, pressure checked 3lbs, tuned at 7 on snail gauge both sides. Timing at 10 degrees and 30 at 3000 rpm
Those 37chokes will kill you unless your running a really hot cam and high compression. Your numbers look good. You might try 180air correction jets to fatten it up. You also need good fuel. Double check your wires and make sure they are not cross firing. Correct heat range spark plug????? Try and autolight spark plug I think its a Autolight 425 Just a few thoughts for you to work on.
thanks Ez, it's 8.5:1 compression with Engle 110 cam. I have 190 airs. I seem to get a lot of smoke when I give the engine gas. was considering F5
I have 190 airs I can use I mean
That definitley is to much carb for that engine. I'm running 34 chokes on my 2 liter and it is to much. I wish I could put some idf 40's on your car just to show you.smooth and econimical and still hit 5500 rpm witch is. about it for a 110 cam. It will rev higher with good sp;rings but your really not making more power after that. 3000 Rpm should be your sweet spot. You can get smaller chokes for the 48's but then you have to do all the jets. You would need at least a 2275 with big valve heads for your set up to work like it is.not to mention nice exhaust. Thats all I got for you my friend. good luck with your project. I'm going to make another vid on this
thanks EZ, A1 sidewinder exhaust. so just try the smaller airs?
my bug need some help it idles to high have to push the clutch in when to lower the idle
For some reason that just doesn't make sense. Need more info
Hi easy Jeezy I like watching your videos and I was wondering if you can help me out in deciding what size IDF carburetor that would be suitable for my 1200 cc Harley Davidson Sportster I found a local shop that can help me out with this project they can build me a custom intake manifold for the carburetor I just need to find out what size I can use I think idf's are the coolest carbs you can put on a Harley
40 IDF
AIR CORRECTION 2.00
EMULSION TUBE F-11
MAIN JET 1.15
PUMP JET .50
IDLE JET .50
VENTURII 28mm
Try and get it to set level. Should be fine with gravity fuel flow but if u use pump less than 2.5 psi
See if these folks will sell you a right side only manifold and keep both cylinders separate
www.cbperformance.com/product-p/3168.htm
@@TheEZGZ Thanks a bunch EZGZ, this is something ive been wanting to do for some time now but the thing is nobody makes a manifold for weber application for a sportster, so it will be a total custom job, thanks to some guys at a custom bike shop, they can fabricate me a manifold, and i will make sure to inform them to keep the cylinders seperate, i also plan on useing 3 inch stacks too, this should be awesome thanks so much:)
do you have a video on how to sync dual 36 dellorto's thank you sir you're the best and how to wire up a electric fuel pump
I've forgotten exactly where it is but if you have the time check out some of the vids in the play list
ua-cam.com/video/uYNil8zC6Iw/v-deo.html
How tight do the jets need to be?
Goodintight but not to tight. Honest is this something you have to be told?????? Over the life they will come in and out a lot. Jets are replaceable. Carb threads are not. Just use common sense.
My dellortos early in throttle stumble floored they roar can’t figure out I need EzGZ
Your going lean. Ether your idling on the progressive holes or you need more sqiurt from accelerator pumps. Make sure you have a nice clean squirt to begin with.
Clogged holes, cracked 0-rings on idle adjustment screws or other place's. Need to start some maint exploring. Wide open don't mean squat. You could stick toilet on top and tune it for wide open. That transition from idle to main takes some practice. I think I cover that. Doesn't sound like you have the snapping and popping. That's a good sign but I still think you have a lean spot. Might be just a partial blockage. Keep looking. You'll find it!
Hello been watching your videos on carbs. Have an issue. Have dellordo carb. And doesn't want to idle. Running duel carbs. I have taken out the idle jets cleaned them out. But still doesn't idle. And it on both barrels. Any pointers?? On what do do? Thanks if you can help!
And it's not back firing. Runs great when opened up.
Idle jets are the small ones and top and then you have the idle needle valves on the bottom side. Right? If they are squeaky clean then you will have to remove the manifold from at the head and check those gaskets. You want thick fiber ones not the stock tin ones. Float level and of course basic tune up: Plugs, Points, Timing, Plug wires and don't forget precise air flow synchronization on all 4 barrels with the linkage removed.
www.cbperformance.com/product-p/0101.htm
Those idle needle valves should be 3 and 1/2 turns out to start and thats pretty close for most engines. All the idle circuit jets and adjusters have O-rings that must be in good shape with no cracks. Metric o rings can be found add most ACE hardware stores
Fuel level is good. We had the carb apart flushed everything out. Jets are totally clean. This is a sand rail buggy. Also has new fiber intake gaskets on it. But after cleaning it all up. Still there is no change on the idle jets when turning them all the way in. No change on the engine idle. So something must still be clogged up? So?? At a loss?. New plus and wires all so. Any other thing it could be??
The o rings are in great shape also on the needle jets and idle jets. No cracks.
Hello, I have a question. I currently have an 1835 in a 1956 beetle. I constantly have back fire/popping. I have duel Empi 40 mm carbs and am seriously thinking about going to 1 Empi 40 mm carb. Is this possible to use one of my existing carbs? Thanks
Jeff
Don't do it. It won't work well at all. Those are good carb choice for 1835. You have a lean condition. Clogged idle jet or a vacum leak. It is very hard to work on in the car I know. Make sure the accelerator pumps are squirting the same. Make sure the linkage is the same and both leave the idle stops at the exact same time. Get a flow meter to make sure both carbs are pulling the same. YOU CAN DO THIS, .will love them when you get them dialed in. DO IT
Thank you sir. I/we appreciate you sharing your knowledge on VW's. I will keep working forward hopefully eliminating the popping. I appreciate you.Jeff
If you can get it to run while popping. Remove a wire from the distributor 1 at a time. If it runs worse that cylinder is firing. If there is no change that cylinder is where the problem is. Sometimes a bad plug or wire can act the same. If your points close up it changes your timing too. Just slowly check out the whole system. Good Luck with your project
EZGZ, I really appreciate all you tell me/us......I removed all wires, each ran worse (good thing) I put a flow meter (Snail gauge) on all 4 tubes. They are all within 1/4 ( Not sure what that means though). My popping has reduced quite a bit though, thanks to your support and useful information. I do have a question, I have 1 1/4 velocity stacks on each carburetor, my air filters are 3 1/4 tall. Would it help if I remove the stacks or put taller ones on.......I am so so close I feel good with the direction things are going.....
Do Not remove the stacks. They actually help low and mid range performance. When you use your snail meter you have to take off the throttle linkage at one side. DO IT. Now at idle use your snail meter and try and get them the same. Don't worry about every stack. Just pick the same one on each side of the engine. When you get it the same and only then reconnect the throttle linkage and make sure they leave the stop when you push the throttle. Use the point where the throttle wire connects. Don't not push on the rods close to one carb. Sloppy worn out linkage needs to be REPLACED. Your almost there buddy.
I just keep it simple stupid and run Kadrons.
Thats good enough for most people