carbs for dummies...

[Big Rig]

my carb is out of tune and i've been messing with it for a week now, but can't get it adjusted correctly. my first problem is that i don't even know what the screws do, so maybe somebody could start by explaining that to me. i have a carter carb with two screws in front.

is there a tool that can help adjust the carb properly?
~Pedro

 

[69 Bronco]

Pedro,

First the two screws in front should be air and fuel mixtures.
Turn them in less air/fuel turn them out less.
I would get a tach of some sort so you can set the RPM and and monitor it as you adjust the mixture.

That is how I did mine according to my hanes/chilton book.

That is the hard way and I am sure someone here will have a better way.

 

[Doyle]

I use a vacuum guage and tune for highest reading. With the engine off turn the screws all the way in until lightly seated, back them out two turns off the seat, start motor, try a quarter turn at a time keeping screws the same turns out until you reach peak reading.

 

[Gummi Bear]

Yours looks like this, right? Except with a black sticker where the red one is on this.

What Doyle told you is good stuff. A vacuum gauge makes tuning them SO much easier. I learned to do it by ear (and badly at that), using a vac gauge sure helps.

Here's a link to your owners manual:
http://www.edelbrock.com/automotive/eps_intro.html

There's a whole section on how to tune your carb.

 

[Big Rig]

thanks, guys. can i get a tach or vacuum gauge at my local auto parts store or will i have to order it from summit? how much should i look to spend on a quality tool?

 

[Ed74]

Hi Pedro,

I just recently had my carb rebuilt by a local store in San Diego. For about a year I have had problems with my carb running either to lean or too rich. I also had absolutely no throttle response and horrible gas mileage. Therefore, I finally decided to take my carb to San Diego Carburetor, on University Ave. The owner performed a spectacular job! I it was costly but well worth it. It turned out that my carb had to be rebuilt and re-calibrated to work properly. Also, I needed a heat tube installed to heat up the air within the carb. Now I have perfect throttle response and better gas mileage. I am running approx. 12 miles per gallon. Let me know if you would like more info.

Take care,
Ed

 

[broncnaz]

thanks, guys. can i get a tach or vacuum gauge at my local auto parts store or will i have to order it from summit? how much should i look to spend on a quality tool?

You can usually get a cheap vacuum guage at any autoparts store I one that is just like regular auto gauges you can get a big vaccum/ fuel pressure guage but I think they coast a lot more.
As for a tach again you can get one at any parts store some automotive electrical testers have them built in. But I like to install a tach on all my vehicles so I buy the regular ones to mount on the steering column. I'd check summit racing as they have a large selection if you want to go that route.
Timing can have a lot of effect on setting the carb so make sure your timing is set properly before messing with the carb.