Getting A Good Clean Idle From Your Carbureted Engine - Here's How Idle Systems And Circuits Work

Repairing and tuning carbs is easy once you understand how they work.
All of the carburetors we commonly use, Holley, Edelbrock, Rochester, etc. are all of the downdraft variety and all share idle system circuitry that is very similar.
Here's a rundown of how they work, are routed, and how things like air bleeds fit into the picture.
#classiccar #musclecar #engines
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[@uasparts]

@8:30 Torch tip cleaners! How you been around this long and not utilized torch tip cleaners on carb jets and circuits, uncle Tony! 😆🤷‍♀️

[@UncleTonysGarage]

Torch tip cleaners are serrated. I want to clean the passages, not bore them out.

[@uasparts]

@@UncleTonysGarage using appropriate sizes, of course. You want the serrations to measure slightly smaller diameter than the hole you are aiming to clean, of course. I failed to mention that. Another plus with tip cleaners, the crud ends up embedded in the serrations instead of pushing the crud further into the circuit you are cleaning. 👍🏾

[@ACDC5540]

Makes it run a smidge richer nbd

[@uasparts]

@@ACDC5540 it can for sure, if you overdo it, perform it with force, or are inexperienced.

[@gibbsey9579]

If you have a close look at torch tips you will see that the serrations are not sharp, they are rounded and will not increase the hole size unless you force a tip in that is bigger than the hole.

[@alsmith9298]

A demo would be great for us kids. This is good stuff.

[@craighansen7594]

Don't overlook a good blast of compressed air. When you are sure all the passages are clear, hit them again with carb spray followed by air nozzle. I highly recommend a full face shield or at least safety goggles! Even a tiny amount of carb spray on your eyeball will give you a really bad day!

[@adamrodenberg1557]

Metal guitar strings also work great for cleaning out those small passages/holes. They come in many different gauge sizes. They are very stiff/hard to bend. Find a friend who is re-stringing their guitar and they'll probably give you the old strings free.

[@interestedlen8823]

👏👏👏

[@ketobeast8489]

Bread ties too

[@Broken_Yugo]

The wire brush wire is a trick I use too. I find whenever you're working inside an unfamiliar carburetor it pays off to inspect the thing for a minute to figure out the circuits, if you know how everything is supposed to work you can test every function before assembly, more or less guaranteeing success.

[@optimusprimer4392]

Bread ties are my best friend when it comes to idle circuits perfect wire

[@brianandglendaharkin9457]

Our AP5 Valiants in Australia had the single barrel Holley on the 145 Hp slant Good clip Tony . MOPAR boy from down under 👍🏻

[@silkysixx]

I feel like the ultimate beginners' guide to getting your carby to run right would be a strip, rebuild, adjustment, install, and calibration of a Carter/Ball & Ball single barrel. Any intention of putting something like that on the channel?

[@joeteejoetee]

GREAT TIPs Tony. Getting new mechanics to find and learn from the schematic for their carbs is a key tip!

[@burguul.]

Best uncle ever. Dude rocks for sharing all this og hot rodder knowledge. Thank you 💪

[@irocitZ]

Thanks for posting these kind of videos, I need all the help I can get. I've had and will most likely always have at least one carburetored car, stuff like this is helpful big time.

[@ShakeYourFist]

Great video with lots of good tips. I have an Ultrasonic cleaner at the shop. They doughnut cost the world, and if you do a lot of Carburettor work, are worth the investment. Way back when I lived in the USA, there was a gallon bucket that you could soak a carburettor for a few hours, and it really came out clean. For the Ultrasound, I have found that 20 litres is the minimum, anything less, and doing the throttle bodies is a compromise. I hope that your next video explains the idle-transfer slot, and enlarging the hole in the butterfly-valve. All the best from Germany.

[@HumveeB]

Hey Uncle Tony, love watching your videos! I want to say it helps ease the pain of being in my hospital bed in South Carolina. I faithfully check daily for your new videos…. From a fellow lifelong classic car lover, keep it up! I know you help and uplift many classic car loving people from their life challenges.! Brad in SC (though grew up 27 years in northeastern NJ) Keep on! 😊👍🙏🏼

[@fastinradfordable]

Smooth recovery for a smooth brother man.

[@glockman8091]

Excellent advice UTG

[@dongeorge4037]

Always good and useful information.

[@kenleppek]

Stripped bread bag tie is my go to.

[@edge2sword186]

Nothing beats a Guitar string for cleaning those passages.

[@kuyamakel]

I used guitar strings to poke through holes. Nice video.

[@marcgucciardo1942]

They are great at poking holes into my fingers 😂

[@lgude]

At 80 I’m not likely to have to rebuild another carby, but your videos are often solving mysteries I’ve been wondering about for years. Like carbies or freak ignition problems I couldn’t fix. In 70s I found it was so cheap to get a new carby from J C Whitney that if I got stuck rebuilding I would just buy a new one. I remember a 190 Mercedes that was never quite right. J C sold me a new one for $30 and it did the trick. Keep ‘em coming, mate.

[@gordocarbo]

I miss those old jc whitney catalogs had some neat junk in them. They were selling clear dist caps many yrs before the catalogs of speed shops did

[@treninness7112]

Great video UTG

[@Mynextproject_74]

Thanks for the info!

[@MsKatjie]

I always get something outa it. Thanks. Even when one reckons he knows it!

[@haroldgetchelljr3264]

Very good video Tony

[@North700]

Thanks UTG

[@Moletastic69]

Removing the metering block and prying out the little lead plug out of the top, in the Slant 6, Holley Model 1920 Carbs, to clean the idle circuit, JB Weld a cover back over it! Now I know!

[@ercost60]

Loved that ciggy smoke wafting in front of the camera at 0:55

[@Experiment-cp1gj]

I have bought a ultrasonic cleaner just because I get tired of buying carbs for my small engines I can get 3 cleanings give or take till they are completely junk. I know non ethanol,tru fuel, it’s all crap nowadays av fuel is good but expensive. I use guitar strings they work great. I have also done a few Holleys and a ultrasonic cleaner will pay for it’s self in no time if you have a lot of carbs around.

[@stevemino142]

Best channel on KZbin good video

[@HYDESCRAZY]

You are the man..a strand of wire or copper wire,if thr real bad I'll just nip the wire with cutters to make slashes in the wire to help remove heavy buildup or oxidation.

[@warrenlucier5796]

I take the spring from a motorcycle fork seal snip it and stretch it out and then it can be used to clean small orifices. I used to overhaul and clean a lot of motorcycle carburetors.

[@sydneychase780]

Ok in the old days we would deal with really disgusting carb clogged. We would disassemble and soak in carb dip then boil the carb, not using the good pots. Blow out with air. Usually probe the passages 1st. Also i have used a small household steam cleaner looks like a electric tea pot, (my wifes suggestion) fair amount pressure. Looks like new when done. The E10 gas will leave deposits of dissolved rubber from hoses. Really hard to get out, these procedures will clean it. Had this happen to my performer recently, steam cleaned, runs like it did 20 yrs ago! Good luck, God Bless!

[@deankay4434]

There is fuzz on gaskets in a carb rebuild kit. I have had 4 or 5 that would not idle to react to screw changes. Rev the engine up to 2K, wad a good cloth shop rag and cover the top of the carb as it dies. Stopping just before it dies, check for proper idle screw settings from seated, backed out 2.5 - 3 turns both, cleans them right out by suction. I use safety wire to check circuit, but rubber tip air blower to feel the air pass thru. Chemicals, Sea foam has never worked for me ever. Berrymans Chemtool B-12 will. The solvents are strong enough to open a varnished jet or circuit. True with anything, like a radiator. If a number of tubes are plugged, chemicals will hit the debris and stop. It can't clean it. The radiator shop will boil it! An older guy who owned this shop for 42 years, say watch this. So a week mixture of sodium hydroxide & h2o, is heated to boil. He puts on a sealed cap no pressure release, inlet hose adaptor is picked and he turns on a pump that has magnets coupled to a centrifugal impeller and feels the core tubes. Cold! Yes, these are plugged but since solder doesn't melt until 450-510 depending on tin ratio plus the hot tubes expand, the radiator grows, watch. Little by little the core tube became real hot all the way to the other tank. He just felt with two fingers, fast, checked them all and shut it off. He put on welding glove, removed the hose and cap a ran the solution thru the inlet and would shine a light (When end Tank type) holding it up at an angle and you could see the liquid come out one by one until it reached the top. Hose off, sprays some chassis black and hook with a radiator handle and let it dry. He was done in 8 minutes easy. DK, ASE master since 78.

[@mrkultra1655]

Thanks Tony

[@87speedshop27]

I use guitar strings to clean carbs. Works great

[@artjones2498]

Torch tip cleaners work good

[@jmatthew007]

Thank you for this, I think it's exactly what is happening to my father-in-laws corvette that has been sitting for a while, it runs but doesn't idle and just stalls out.

[@gordocarbo]

If his choke is working right check the float levels, make sure theres no vacuumleaks

[@fairlanephantom]

Thanks for pointing out manually cleaning the idle circuit. I was chasing the mixture screw position with bigger jets because the book says to go bigger if you need to back them out too far. But in the end it never really changed needing to be 3 turns out. Whenever it acted up by not responding to the screws, I'd blow it out with air and it would be adjustable again. But with how often i seem to have to do that, it would make sense to get back in there and clean the rest of the passages. The car in general runs great, but it's at idle little issues pop up.

[@fairlanephantom]

Update: Went took the carb off and did a fresh kit with carb spray and a compressor.and got in the holes with guitar strings. Done in less than an hour and now the car starts at 1.5 turns, I never got it under 3 turns and I've had the car for 8 years. Thanks Tony!

[@mannyR4098]

Guitar string works good too.

[@stevenmitchell5612]

Could you please address having a really big cam and needing to open the throttle blades for more air and what to do instead so you don’t get into the intermediate circuit? I think I have that issue and don’t know what to do.. kinda afraid to start drilling butterfly’s. Thanks

[@rickhaile2190]

Depending on the size of cam,and if you are running a Holley carb. the easyist thing to try is turning the carb. upside down and reversing the secondary idle speedscrew. Back off your primary and open up your secondary screw. If this does'nt work you'll need to open your idle air bleed.

[@scotcoon1186]

Rick Pewe and company would get it running high rpm then stuff a rag in the top of the carb, the vacuum spike often moved enough gunk to get them off the trail.

[@obsessedwithcars219]

Thank you for all the content Uncle Tony!!!

[@Nathanmr19771]

Good info. I’ve been thru most of these models so know enough to be dangerous lol. I wondering if you go over the dreaded flat spot fix on carbs during part throttle/ from idle circuit to part throttle? I’ve encountered this on most models from new out of the box to ones that have been sitting and haven’t really got that transition perfected 🤦‍♂️ One carb I’ve been using FST 650 has been only one that hasn’t caused me issues

[@kerrynaylor8520]

I still can’t get a consistent clean strong idle with my dual Holley 600s on my 72 “GTX”….. after resolving multiple issues with my 50 year old carbs, the only thing I can see that may still be a problem is my throttle shafts are slightly loose in the baseplates. Can this cause a high irregular idle? (My problem). How do I fix the play in the shafts? You have given me solutions to MANY other issues in your awesome videos- thank you!!! Also, how should my idle mix screws and throttle be set for a good idle with dual quads? (How is slaghammer set up??). With my throttle blades shut (idle screws backed off completely) it still idles at 1100 rpm. Mix screws are all 1 turn out. 1.5 raises the idle to 1500…

[@cyberburnzy]

My 84 Toyota has a fuel cut off solenoid at the top of the idle circuit. It wasn't getting power and was staying closed. It turns out a fusible link wire was down to a couple of copper strands. I fixed that and now you can hear the solenoid open up when you turn the key to IG.

[@fastinradfordable]

Put updraft carbs on a slant 6

[@rctopfueler2841]

the good ole boys taught us if it wouldnt idle or balance to warm it up a bit then you went W O T hold it and close the choke at same time right up until it was about to die, release and repeat and it 99 percent worked to get it to idle again, so im not sure what it did but it worked

[@rctopfueler2841]

@@321CatboxWA i have but not a mopar or a ford, the gm motors do not backfire like those 2 do..

[@randymacsgarage]

Tony a while back you rejuvenated a battery with your welder how is that battery holding up? Thanks

[@williamhowland1171]

UT I love you bro, God Bless you bro 🙏💕

[@AtZero138]

Carburetor Mystery Corner... Think it thru.. Small adjustments.. Keep on wrenching folk's @∅🇺🇲

[@DuckyHunter812]

Laughed my butt off at your clip on D&D Speedshop's 100,000 subscriber video. Y'all should add a little 1 or 2 inch youtube plaque to the right sleeve of the next 1000 shirts sold.

[@ewconway]

I had the exact problem with my Holley carburetor that sat on my 383 in my 1969 Dodge Charger. The meeting screws did not have any affect on the carb no matter what I did with them. Another great educational video. 👍

[@nFlames2]

I have seen engines with tight cam Lobe-Separation Angle one has to crank up the idle speed screw way too much to idle. And the carb is opened to the point the idle circuit is no longer in play & metering screws make no difference. What I have done is drill or 3/32 - 1/8 hole thru the primary butterflies as an air bleed to be able back off the idle speed screw. Once i have done that the primary butterflies are at a point the metering screws are adjustable.

[@stephenh.bunkybyrd2024]

Thanks

[@Jake6837]

Tony I'm watching this right now. If liquid can't clean a passage. Use guitar strings. They tell the gage on the strings.

[@cheechmagee8512]

Hey Tony, can you show us how to tune some 660 center squirters? I’ll be putting some on a tunnel ram.

[@richardcranium5839]

our school shop teacher showed us a trick worth mentioning. back out the idle screws 3-4 turns. swap 2 plugwires 180 degrees apart on the distributor(remember which ones!)start it and floor it 3-4 times. it will backfire. shut it off and reverse those plug wires back to their original positions. start it and floor it while manually closing the choke untill it dies once maybe twice. then readjust the mixture screws. as he explained the backfire creates a pressure wave back through the carb loosening up a blockage then running it with the choke will suck that dirt through the high side which is larger and it can easily pass. if it works fine if not you only spent a couple minutes and you know without a doubt you gotta pull it.

[@Mohawk62]

Just watched DDs 100,000 sub vid, nice job Tony! It will never go to their heads. Lmao! Nice video on carbs. I have used what I call micro drill bits, I found them at a hobby store to unplug those small passageways. Anyone who has worked on any N scale model railroad trains, knows what I'm talking about. Again, nice video!

[@richardcranium5839]

that's fine as long as you dont enlarge the size of the holes

[@marclobato9690]

Wow rebuilt hundreds of carbs. Tear them down. Dunk them in Berrymans. For a while. Blow them out with shop air. Pipe cleaner and small gauge bailing wire like he said. Run that through the holes. Put it back together. Throw the 5 gas in the tailpipe and tune it. Nuf said!

[@alrui]

What happened to Stuby & better still the slant turbo project?

[@phillipsprague3275]

What also works for these tiny passages is the acetylene torch cleaners these are ridged an and readily available plus they are durable!

[@jasonkaiser5150]

Use those all the time.

[@terrencebuller7676]

Thanks for the tips and tricks Tony. Take care 👍

[@witnesszer0]

i use a safety wire it is really strong and wont deflect like a thinner wire

[@dewreckdeberjack9618]

Used guitar strings can fit the bill nice.

[@James_Hande]

Back in the day our first plan of attack was spraying carb cleaner. Then rev the motor at the same time trying to smother and almost stalling then remove the rag and raise the R's. If that didn't help carb tear down. Spray every thing with carb cleaner and try using air pressure. Last case scenario is the wire trick you talked about.

[@jasonkaiser5150]

Every Carter bb2 never seems to run right I have rebuilt them Myself, bought them new, just never seems right. My terminal quad was great. My two barrel holly 318 started and idled after sitting for 5 years little fresh gas ran great. Am I the only person that has no luck with the bb2?

[@KB19910]

I have a davinci carb on a 383 stroker. Car starts and runs for a little then dies. Pump the throttle and it will fire back up. Sometimes I have to wait a few mins. Then pump and fire it up. You think it’s the carb?

[@andrewoplinger4759]

What about idle passages on a quadrajet? I got one of those with a bad idle circuit.

[@Txchickensnake]

Porcupines quilts. Won't damage brass. A old voodoo carb God showed me this and I have a collection now.

[@RustyShackleford6371]

Found mine every time I got off the highway would idle low. I found timing dropped. Thought I didn't have the distributor bolt tight. Drove around more was fine. Jumped on freeway again timing dropped. Pulled distributor gear is worn away.

[@reginaldbowls7180]

Can we get a full rundown on the carter BBD?

[@charlis4262]

tell us about the lean burn system from the 70s all so the electronic spark control system

[@richardcranium5839]

that would be a 2 hour video. unless your are factory restoring just delete it

[@MurphyTheBandChild]

Another very informative carburetor video from good ol' Uncle Tony. If I could offer some minor constructive criticism, I would look into getting some kind of dedicated microphone for these kinds of videos where you're just sitting at a table and talking about a subject for extended periods of time. It may just be me, but the volume seems to be a bit low and the audio sounds a little soft and/or muffled.

[@jonbertocchi173]

hey tony, i have a weber 32/36 carb. i tuned it and achieved a smooth idle but when i put it into gear the idle gets really rough and sputters like its dying. any suggestions?

[@Goldenhordemilo]

the starter turns the pistons making a vacuum liping off the top of fuel drawing it in.

[@davidlobaugh4490]

Any chance you could do moto carbs vids?

[@freedomparts5869]

tony can we see a slant 6 build with 3 weber side drafts?

[@jonathangehman4005]

Another priceless knowledge drop from the best car channell on KZbin

[@landondc4739]

I got a truck engine that will run fine when warmed up, blip the throttle and it idles like trash. Turn engine off and restart immediately and idles great. Blip throttle again and goes crap. When it is idling like crap, some liquid is coming out the tail pipes and although it is hard to tell, I think the timing increases as well. Am I having a carb issue within the idle circuit or is this an ignition issue maybe within the mechanical advance?

[@bennyharper862]

Well, what works for me is to have someone stall the heck out of the engine and adjust the secondary metering system until it does not stumble or stall when you give it the gas

[@waynee1357]

Uncle Tony what happened to DB Cooper?

[@genehart261]

Gotta' love a carbureted guy in a fuel injected world!

[@happyhermit6899]

Guitar strings.!!!!!!

[@markschmalenberger8301]

That's my go to choice. They're cheap and come in increments like cylindrical feeler guages,excellent. 👌

[@daveharris7734]

Key words clean em out. Related My bike "carbureted" and .guv gas o hol. Plastic screen in tank gave up and a piece ofit lodged in my cab. I couldn't find it or about 3 others. I'm a firm believer in sonic cleaners. Ubetcha.

[@martinadams7949]

welding tip cleaner works to clean too

[@stuckinmygarage6220]

Did we miss the link to last week's?

[@egodeathplease]

Tip cleaner from oxygen acetylene torch

[@met454]

So funny that I’ve used the brush bristle and the bread tie in the past for the same issues! 🤣 Mainly on small generators. 👍🏻

[@boss351gt6]

The tech videos are my favourite right after the burnout ones =)

[@philedwards1460]

I can screw my idle screws all the way in and the idle keeps going up. Summit carb. Plugged?

[@pottypete5593]

Does mig wire work ?

[@phillippearce9680]

👍

[@jimmungai1938]

I’ve never had to do that before but I would use a torch tip cleaner and take the one that fits down in there and you know how you got the smooth portion of the tip cleaner taken file too far take a sharpening stone and file two flats on each side of the tip cleaner and then you twist it around and will actually help dig through there I do that all the time with a roller I run for asphalt are water sprayers clog up and it’s the same thing basically and anyway yeah you just take your fingers and twist it back-and-forth like you know anyway this is six in a row Jim I go by six in a row Jim I have a 91 dodge pick up with six in a row under the hood yeah it runs diesel fuel

[@RudeMoparDude]

Tony✌🏼Kathy, you 💨 again!? 😮 need to quit again myself🤘🏼🔧

[@RobertsGarage]

👍👌

[@gordocarbo]

Out ehtanol laced gas in ca sucks. Dries out eveerything inside to a crisp if you let them sit a long time. Growing up a car could sit for yrs and fire right up

[@rondpert5167]

I was running a tripower on my big block Chevy (because hey, it's a tripower) and had idle problems. You could adjust the idle to 800 but it would tend to stall on the road. It idled better at 1000 but after driving it would always creep up to 1300. So now I have a 4 bbl Holley (from a rebuilder) but it seems to have the same problem. The motor is basically stock with a bit of an aggressive hydraulic cam.

[@tl5108]

Wonder if it’s something with your distributor? It set up to advance at very low rpm?

[@rondpert5167]

@@tl5108 8 degrees BTC

[@williamrogers.]

Poke out the jets with a strand from a wire brush. 😉

[@bob8776]

My bread comes with plastic clips instead of twist ties so I guess I'm going EFI...

[@petar443]

0:23 WHERE is the link ? You've forget it ?

[@sydrider6023]

This is all easy to do once you have located the circuit passage going up and the one going down and the transfer horizontal one. Carb cleaner is strong and will normally clean these little tunnels. Multi barrel carbs have two idle feed circuits.

[@danlindeke2561]

What was the carb 20 years ago that looked like square box,Predator?

[@firebird77clonefirebird89]

Demon?