Dummys guide to carburated engines

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Kipprc

Kipprc

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Please excuse my ignorance. My old man isn't much of a mechanic and I came up in a time without carburetor's. Can somebody point in the right direction so I can read up and talk intelligently about the subject? I have a 1970 Duster and I am trying to figure out this engine and the components that allow it to run. Before I add EFI I need to learn about carburetor's. How they work and how to adjust them. Its only right to understand what I have before I move on or upgrade. I want to know what is under the hood and what it does. There is so much space If you can point me to a book, video or a guide for the Mopar small block engines, I would appreciate it.
 
Carburetors are like a box that you
Open up and let the magic out. Honestly we all make up terms on the fly to sound really cool.
Lol! Plenty of HP books on specific carbs and other books on general repairs. Carbs are not magic. Very simple actually. Good for you for trying to understand how they work!
 
You may figure carburetors out and decide NOT go with EFI. Just because its newer tech, doesnt necessarily make it better, or easier to work on. Definitely NOT cheaper that's for sure. I prefer carburetors and an old skool timing light. JMHO, but other than this little 3" x 5" rectangular screen I am typing on that doubles as a phone, TV, camera, computer, Eff all that computerized ****. Theres a place for everything, a computer belongs in your pocket or in your house, not under your car hood.
 
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Agree that the HP Books Holley Carburetors and manifolds has a very good section on the fundementals of a fixed venturi carb.

On-line, you can go to one of the Chrysler Technician's pamphlets and A/V presentations here:
Master Technician Service Conference - Chrysler's Training for Mechanics
1966 is a good one, and pre-emissions which keeps things simpler. But the 1970 is OK too.
They are also available at mymopar.com in a different format. I like the imperial club because its not-for-profit, no ads, etc.

I'm also going to suggest at least glancing at an overview of the ignition system because timing and fueling work together.
This one from 1969 is as good as any Ignition System Analysis (Session 259) from the Master Technician's Service Conference
 
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I recently did this exact same thing with my father. I wanted to learn about carbs and help my father (with his Mopars). The best thing I did was buy a decent carb off eBay and watched a video for rebuilding that precise same carburetor number. Mine was a Holley 3310-3 (4 bbl with vacuum assist). There’s lot’s of videos out there and, the trick kit (to rebuild with) + cans of brake cleaner were not all the expensive.
 
Kipprc said:
Please excuse my ignorance. My old man isn't much of a mechanic and I came up in a time without carburetor's. Can somebody point in the right direction so I can read up and talk intelligently about the subject? I have a 1970 Duster and I am trying to figure out this engine and the components that allow it to run. Before I add EFI I need to learn about carburetor's. How they work and how to adjust them. Its only right to understand what I have before I move on or upgrade. I want to know what is under the hood and what it does. There is so much space If you can point me to a book, video or a guide for the Mopar small block engines, I would appreciate it.
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Like the above post mentioned, I'd see what carb you have (Holley? Edelbrock?) and look at videos of how to rebuild it on youtube. Things that don't make sense, ask. In short, the vacuum from the engine pressurizes the carb from the top causing fuel to flow. The amount of fuel flowing is determined through jet size, amoung other things. But I think it's easier to learn about one carb than to try to learn of them all. Then, a lot of your knowledge will cross over to other carbs
 
David Vizards books on induction are very good. Lots of intake and car stuff in there. HP Books is the publisher. They are a little pricey now that Supershops doesnt sell them for $9.95 a piece.....Ooh, that dated me.
 
Thank you folks. I do appreciate it. I got some of these books on order and I will order more. If you have any other suggestions, I am listening.
 
Kipprc said:
Thank you folks. I do appreciate it. I got some of these books on order and I will order more. If you have any other suggestions, I am listening.
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You should go into the fuel systems forum here, and search for anything that Mattax has posted and read all of that, and the links he has posted. There are HUGE mistakes in those books and if you don’t know what is right or wrong. Then you adopt poor tuning methods and incorrect understanding.

12many also has an excellent thread on power valve tuning in that forum that is worth the time to read it.
 
I have David Vizards carb books too. He does a very good job of breaking down what a carb does. It's easy to follow what he's saying with lots of diagrams and pictures.
 
One problem is, that carbs "vary." Something like a tractor/ outboard/ small engine carb is much different than a U.S. automotive engine carb. I say that last, because the traditional Brit/ other carbs are also different, they work more like a bike carb. "That is," the throttle is a sliding cylinder which pulls a tapered needle out of a jet in order to control fuel ratio as the throttle opens. some of these have a vacuum arrangement.

Even with US carbs, different ones are ............different........Older Ford/ Holley pretty much all used power valves. Carter/ others/ GM Quadrajet and Carter thermoquad used a vaccum piston(s) with a spring, to push a tapered metering rod up out of a jet to control fuel, "the power circuit.' Holley (and others) power valve is a vacuum diaphragm which opens a little poppet valve, allowing more fuel in addition to the main jets.

The nightmare electrically controlled carbs of the late 70's and 80's before EFI.......the designers should be taken out and shot........many times.........over and over.......with pellet guns
 
My dad had a 1981 ram 150 with a slant 6 and an overdrive 4 speed. It had a feedback electric carb, distributer without vacuum advance, and that lean burn computer on the air cleaner. It would run ok then run rough. Sometimes wouldent run at all.

I removed the electronic advance distributor, lean burn computer, and carburetor. Then I dewired it and rewired it for a regular electronic ignition box, installed a holley model 1920 1 barrel carb that I cleaned up and kitted out. A 1970 pass car air cleaner, and installed a vacuum advance electronic distributor I pulled out of the junkyard and rebuilt. After that the truck started easy, and ran great every time.

My dad wanted to keep the old carb, computer distributer and ****. I looked at him like he was nuts, and said what the hell for. Then I picked the carb up, made the toss halfway across the shop, made a perfect basket right in the trash can. Repeated it with the rest of the pieces we removed. I told my dad, that's where all this crap belongs.
 
Take some pictures and find out what you have. Holley has a "list" number on the top facing front of the carb. Carter has the number on the right ( passenger side) front base, Carter TQ number is on the left rear base. That car is 50 years old, hard to know what is on there now.
 
66fs said:
Take some pictures and find out what you have. Holley has a "list" number on the top facing front of the carb. Carter has the number on the right ( passenger side) front base, Carter TQ number is on the left rear base. That car is 50 years old, hard to know what is on there now.
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I have. I made post about it in another section to try and get it identified. As of right now no luck. Whatever it is, it works.
 
moparmat2000 said:
You may figure carburetors out and decide NOT go with EFI. Just because its newer tech, doesnt necessarily make it better, or easier to work on. Definitely NOT cheaper that's for sure. I prefer carburetors and an old skool timing light. JMHO, but other than this little 3" x 5" rectangular screen I am typing on that doubles as a phone, TV, camera, computer, Eff all that computerized ****. Theres a place for everything, a computer belongs in your pocket or in your house, not under your car hood.
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Cmon Moparmat, save him the aggrevation we all go through with carbs. Stuck float bowls, ethanol laced gas that destroys rubber and gaskets and ends up in the float bowl. I had one last big fire with a carb and vowed to never put myself through that bullshit again.

Modern EFI has its ups and downs but in my opinion is far superior to fine tuning than a carb will ever be.
 
Sorry mini, carbs it is for me. I can look at mechanical stuff and figure it out. This electronic injection stuff nope. Only reason I have it, is because my daily driver and my wife's daily drivers are both newer cars with it. Personally I hate it.
 
It's TRUE that the blue holley book has some blips, the editor just have been an "expert" lol the red one is great though for getting you started in aiding the basic tuning and function
 
mini said:
Cmon Moparmat, save him the aggrevation we all go through with carbs. Stuck float bowls, ethanol laced gas that destroys rubber and gaskets and ends up in the float bowl. I had one last big fire with a carb and vowed to never put myself through that bullshit again.

Modern EFI has its ups and downs but in my opinion is far superior to fine tuning than a carb will ever be.
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Holley?
 
Kipprc said:
I have. I made post about it in another section to try and get it identified. As of right now no luck. Whatever it is, it works.
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Ok, saw that. Get a book on Carter AFB carbs. Weber and Edelbrocks are just clones. Nice carbs. Is it giving you problems?
 
Chrysler Tech is Carter oriented.
The fundamentals are the same so its not a big deal for introduction to how they work.
Carter used a second bleed in the idle circuit they called an 'economizer'. Another difference is the use of a balance tube insead of a vent. These are getting into a level of detail well beyond basics.

The Imperial club has a some Carter manuals on-line.
At some point you will need to open one up. When you see the parts and follow those instructions, there will be no explanations about what they do. You put the two together; the parts you're holding and what you read about how they work.
Eventually you'll make changes, maybe just small ones like adjust idle mix, and observe what happens.
 
I've seen & heard horror stories about the after market EFI systems out there. I was toying with going EFI on my bracket car & was looking into it about the same time. I talked to a fellow bracket racer who had EFI on one of his cars & the other still had the carb on it. We talked for a while & he told me that depending upon where all I planned on racing that my best bet was to stay with a carb because of the tuneability. I have built so many Holleys over the past 50 years, that can probably do it in my sleep. Right now, I'm experimenting between a 4779 4 point idle circuit, a 4779 2 point idle circuit, a 750 Street Demon, & a 750 Race Demon. The power valves in them have been blocked & my fuel regulator has a return line on it. I've made 7-8 hits on each carb & so far, the 4779 4 point carb has run the best. I will continue to test them until I find the one that performs the best.
 
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