Carburetor Idle Mixture Tuning

Подписаться 8 тыс.

Просмотров 59 тыс.

50% 1

Carburetor Idle Mixture Tuning. In Part 2 of my series I show you how to properly tune your idle mixture circuit on your carburetor using nothing more than a tachometer and vacuum gauge. I also show you the proper fuel pressure and how to adjust your fuel pressure should it be too high or too low. All of this is done using an Edelbrock AVS2 650cfm carburetor but the same theory applies to Holley, Quick Fuel, Brawler, Demon, etc.
WATCH PART 1 FIRST. If you haven't seen the first installment on how to properly install an Edlebrock carburetor check the link below: • How to Install an Edel...

Авто/Мото

Опубликовано:

18 июл 2021

Ссылка:

Скачать:

Готовим ссылку...

Добавить в:

Мой плейлист

Посмотреть позже

Комментарии : 51

@splooshes2 Год назад

you helped me understand a decent amount in this bro thank you. I still don't know shit but I'm learning so thanks!

@SpeakerKevin Год назад

I installed the pressure gauge in the spare outlet on the pressure regulator, works great.

@leedan9887 Год назад

Like your car man

@vernm6189 2 года назад

I run my fuel press. at 6.5 without any issues, with the same 289/306 engine. @ 14" manifold VAC. 1st on Race Day !

@carlosmolinares4329 Год назад

Me encanta la mecánica

@DjTragik951 Год назад

First thing is to adjust air mixture screws then the RPMs? When I set the mixture screws to about 17 in m. My rpm is about 1400 then when I bring the rpm down so does my vacuum it goes to about 15” m. I’m still trying to learn how to adjust my AVS 2 carb

@truckandroll989 Год назад

Out of the box the carb is going to have some baseline settings. Assuming your fuel pressure is good, engine is fully warm (choke open) id likely get rpm set first and then start adjusting IMS. Adjusting them will affect idle and also vacuum. You are shooting for highest vacuum at desired idle rpm.

@bluecollarfox916 3 года назад

What’s your opinion on ported vs manifold Vacuum for the vacuum advance signal? With my n91 cam in my SBF I’m unable to get it to idle at a high enough rpm without opening the throttle blades too much and exposing the transfer slots. Guess I could open the secondaries but I also noticed I was able to get a leaner idle mixture with more advance at idle (manifold vacuum signal). Just what worked for me so far. Love the content.

@truckandroll989 3 года назад

So Ive run both. From my recent research it appears in most cases Ported is preferred except in a situation like yours where you need the extra timing for improved idle quality. The other option would be to modify your distributor to limit total advance so you can run more base timing. Lets say your average distributor adds 20 degrees and you typically run 14 initial… whelp thats 34 total. With a big cam you may want 18-20 initial but not 38-40 degrees total. There are ways to modify it so it stays at 34 total but it definitely involves more tinkering.

@bluecollarfox916 3 года назад

@@truckandroll989 awesome thanks. For its staying on manifold vacuum haha.

@trailerparkcryptoking5213 Год назад

MANIFOLD VACUUM for those with a brain!!! You noticed it increased idle rpm which allowed you to lower base idle and cover up those transfer slots. Don’t drill your throttle plates, crack open your secondaries just enough....

@360escapades Год назад

Very good

@sergiogarcia3719 2 года назад

Apresiate it

@jm-ve8ry Год назад

What about briefly hooking vacuum gauge to ported vacuum just to make sure that at idle, you have no vacuum. If idle speed screw is turned in too far you'll start to get vacuum at the ported spot.

@truckandroll989 Год назад

You could do that if you wanted

@indarbhamra4480 Год назад

Hi, what kind of vacuum gauge do you use, if possible please provide a picture. Thank you. Love your blog. Best regards from Kenya.

@truckandroll989 Год назад

Any of them really work. Preferably one with a larger face so it is easier to read. Here is an example www.amazon.com/Hromee-Carburetor-Pressure-Diagnostics-Leakage/dp/B08P4P97H2/ref=mp_s_a_1_1_sspa?crid=2UVQX0FET4VKU&keywords=automotive+vacuum+gauge&qid=1661361259&sprefix=automotive+vacuum%2Caps%2C121&sr=8-1-spons&psc=1

@corydillon9864 2 года назад

What was the brand or part number for the fuel guage

@truckandroll989 2 года назад

Fragola performance is the brand. Got it off of Summit Racing. Part #: FRA-900001

@sergiogarcia3719 2 года назад

I am runing 3.5 psi on my 1406 edelbrock and is not working properly is the presure low i need 5.5 to run beter

@truckandroll989 2 года назад

Yea I would turn it up and that should help. Between 5-7 is good

@darrellsomers5427 Год назад

Way to low the more the better never seen one as low as yours

@armygreenfj3924 2 года назад

Hey I just bought the edelbrock AVS2 650. Im in the process of rebuilding my 350 with the edelbrock e street top end kit for my 75 blazer. The fuel pump i ordered is a edelbrock mechanical fuel pump rated at 6psi do i still need a fuel pressure regulator?

@truckandroll989 2 года назад

It certainly doesnt hurt to add one. Edelbrocks are pretty susceptible to fuel fluctuations. You could try a fuel pressure gauge first to see what it reads and determine after that if you want to add a regulator

@armygreenfj3924 2 года назад

@@truckandroll989 thanks

@josephmclaughlin9787 Год назад

Yes because sometimes the pumps flow more then Advertised

@armygreenfj3924 Год назад

@@josephmclaughlin9787 or sometimes the gauge is reading wrong.

@CruisinComPTon Год назад

Is it better to do this with an air cleaner on or off?

@truckandroll989 Год назад

Ideally on but thats usually hard to do just for access sake

@garyweber7139 10 месяцев назад

Many classic cars specify the car is to be in drive if it's an auto trans when tuning, just remember to chock the wheels and don't rev it.

@truckandroll989 10 месяцев назад

Yes, this video was specific to a manual so neutral is fine but yes for an auto. Or have someone hold their foot on the brakes

@omarespinoza1804 2 года назад

No issues without a fuel return?.

@truckandroll989 2 года назад

Nope none at all. I believe you can run this either way

@omarespinoza1804 2 года назад

@@truckandroll989 good to know.

@Mr1974dust Год назад

Is it really 100 degrees in your shop if so im sorry .

@truckandroll989 Год назад

Lol it very well could have been! Tall ceilings, no fan, and Utah summer heat can be no joke… despite us being at 4500ft elevation!

@Mr1974dust Год назад

@truckandroll6466 Where do you live Im in sanpete County ut mt pleasant

@truckandroll989 Год назад

@@Mr1974dust i am in SLC

@darrellsomers5427 Год назад

Never seen a raal cam make 25 inches if vacuum lol

@davidkeeton6716 Год назад

Stone stock, grandma ride cam. Go up to 285-294 duration range you are probably going to see 10-12 at best.

@JetBomb-xx6ye Год назад

Best thing usually to do is to take it to the professional

@truckandroll989 Год назад

Lol but why? With the initial investment of a couple tools theres no major secret. Between this video and a few of my others I show you how to get your carb setup properly without the need of a “professional”. Moreover, nowadays you are more likely to find someone who can tune your EFI but is a bit rusty when it comes to a carb. Following this same logic I tuned my 65 C10 before taking it to Westech Performance (Engine Masters, Roadkill, Steve Brule, etc.). They told me my AFR (carb tuning) was perfect and just addressed timing when dyno tuning. It isnt rocket science.

@gypsy6211 11 месяцев назад

Professional? It's a carburator. You walk into an autoparts store and ask for a long fuel filter for a quadrajet, they'll give you what looks like an oil filter for an ATV. Professional carb tubers? There's very, very few left in the country, they've all retired or passed. Today's 'Professional' isn't much more than a computer reading, parts cannon loading, tech.

@JetBomb-xx6ye 11 месяцев назад

@@gypsy6211 yeah im sure you know by the sound of it 👌

@AP-wt9yh 5 дней назад

@@truckandroll989 ...and here I'm watching this and other carb videos 'cause can't find a "professional" to do the carb job for my 1405 edelbrock mounted on a 318 LA mopar in my 1982 CJ7 jeep. Thanks body, I'm new to the carb world.

@truckandroll989 5 дней назад

Youre in luck im in the process of rebuilding a 360 LA. 650cfm carb tuning videos to follow just waiting on some parts from summit. Its torn down right now :)

@bottmar1 11 месяцев назад

I don't agree at all with turning the mixture screws in a fraction from highest idle. That is how all the carbs. were set at the factory in the 70's. There was a hell of a lot of rough idling engines because a worthless lean setting back then. When left this way you will end up re-adjusting them more often because even a little contamination in the idle circuit will create a leaner condition causing a bad idle. A slightly lean condition will cause a rougher idle than a slightly rich condition. Turning the mixture screws out a quarter turn rich gives you a fudge factor against a lean condition so you won't see your customer back in your shop as often. I have adjusted mixture screws a little rich for 53 years and don't have see my customers as often. They like that better. (And no, to you guys that think you will gas foul the plugs. You are wrong)

@truckandroll989 11 месяцев назад

I dont think thats bad advice. One could argue you can still shoot for highest vacuum but perhaps not lean them out past that point?

@bottmar1 11 месяцев назад

That's better then setting them the government E.P.A. method but barely. I new what the E.P.A. guide lines were by noting the mixture screws position when adjusting the new cars back the seventies after I pryed those damn plastic caps off and found them about a sixteenth or slightly more turned in from highest idle speed. I put the kibosh on that and turned them out from then on 1/4 turn. I'm glad you seem to understand the value in my method. So many RU-vid warriors take the "book" method to heart but you are more flexible. Thanks.

@truckandroll989 11 месяцев назад

@@bottmar1 and so i better understand the issue back then (and likely now) was the small orifice created by the lean IMS setting was prone to being further reduced by debris which could cause the need for further adjustments/lean stumbles off idle, etc. I doubt a 1/4 turn made a very big difference in AFR/idle speed/vacuum but it sounds like it reduced the need for more regular maintenance.

@bottmar1 11 месяцев назад

That is correct. You get a little more time between adjustments without runabilty problems. Catch cha later.