How to rebuild automotive carburetors
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*CFM, and how much do I '''need'''? (Cubic feet per minute of air/fuel mixture) | *CFM, and how much do I '''need'''? (Cubic feet per minute of air/fuel mixture) | ||
| − | + | [http://www.4secondsflat.com/Carb_CFM_Calculator.html Handy CFM Calculator] | |
*Spreadbore vs. squarebore -- which one is required? | *Spreadbore vs. squarebore -- which one is required? | ||
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==Holley Carb specifics== | ==Holley Carb specifics== | ||
| − | [[Image:Holley.jpg]] The | + | [[Image:Holley.jpg]] The model 4160 Holley 4 barrel carburetor. Along with the model 4150, its design has changed very little since its introduction in 1957, and the design and tuning techniques still work on most of the newer ones. Easy to rebuild, easy to tune, and having LOTS of aftermarket repair and hop-up parts, the 4bbl Holley may be the best choice for you! |
==Rochester Carb specifics== | ==Rochester Carb specifics== | ||
[[Image:Rochester.jpg]] | [[Image:Rochester.jpg]] | ||
| − | The Q-JET,quadrajunk,quadrapuke,whatever you | + | The Q-JET, quadrajunk, quadrapuke, whatever you want to call it- if properly tuned- is one of the best carburetors available on the market. |
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| + | It does have its restrictions though. If you are running a fairly healthy cam profile that has a tendency to limit your vacuum level, the Q-jet power piston spring needs to be selected carefully- just as you would do a Holley power valve. Several companies do make different springs for this, but I can tell you from experience, if the cam is to big it can give you problems. | ||
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| + | With it's centrally located fuel bowl and the aforementioned power piston, the Quadrajet is a great all-'round carb for street machines and if your doing a restoration on a 60's or 70's muscle car, the carb just can't be beaten. Once tuned, it stays that way, with very little need for upgrades or maintenance. It's true, that it is a little more difficult to rebuild because of it's varied tuning characteristics, but that is the beauty of the beast, you can make it work on just about any engine design. With it's small primaries, you can cruise and get reasonable fuel mileage, or you can kick in those monster secondaries, forget about fuel mileage,and fly. | ||
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| + | Most rebuild kits come complete with instructions and application charts for whatever engine your working with, and you can always do what I do, hold on to the parts you didn't use before ,and use them on your next rebuild or experiment. Several companies have started making everything you need to tune the Q-jet to fit your needs, or you can buy a new carb from Edelbrock- and I do mean new, not reman- and not worry about spending all of your time in the shop. | ||
| + | [http://www.jetchip.com/ Jet Performance] also makes a great Q-jet. Their unit is a true bolt on and go product. I have used 3 of their carbs, which by the way come in stages to meet your application, and I never had to tune one of them. I bolted to the intake, and took for a test drive, and never had to tune from that moment forward. Again, if your running a nice little street engine with a little thump, you can't find a better carb, but if your getting into that monster pro=street stuff, then you need to look at carburetors that can handle the changes in vacuum circuits and the need for fuel. | ||
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| + | '''Quadrajet Tuning and Repair Parts''' | ||
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| + | [http://www.cliffshighperformance.com/index.html Cliff's High Performance] | ||
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| + | [http://quadrajetparts.com/index.php QuadrajetParts.com] | ||
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| + | [http://www.carburetion.com/index.htm Carbs Unlimited] | ||
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| + | [http://www.carbkitsource.com/ The Carburetor Doctor] | ||
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| + | [http://www.edelbrock.com/ Edelbrock] | ||
==Carter Carb specifics== | ==Carter Carb specifics== | ||
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To do a rebuild I like to get an old cake pan to work in. This makes it so if you drop parts they dont get lost. It is a good idea to take some pictures as you go through the dis-assembly process, they could come in handy for reference later. | To do a rebuild I like to get an old cake pan to work in. This makes it so if you drop parts they dont get lost. It is a good idea to take some pictures as you go through the dis-assembly process, they could come in handy for reference later. | ||
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Usually the top (air horn) comes off first, then the base plate. Be careful if turning the carb over after you have the air horn off as small parts could fall out. It is a good idea to look at the instruction sheet that comes with the kit so you know where all the check balls and other small parts that may fall out go. To remove the air horn there are generally 4-6 screws and some linkage that will need to be disconnected. These should be fairly obvious. Once off you can turn the carburetor over and remove the base plate. On Holley style carburetors with removable metering plates and fuel bowls these also need to be removed. Remove all needle valves and rubber parts from the outside of the carburetor. | Usually the top (air horn) comes off first, then the base plate. Be careful if turning the carb over after you have the air horn off as small parts could fall out. It is a good idea to look at the instruction sheet that comes with the kit so you know where all the check balls and other small parts that may fall out go. To remove the air horn there are generally 4-6 screws and some linkage that will need to be disconnected. These should be fairly obvious. Once off you can turn the carburetor over and remove the base plate. On Holley style carburetors with removable metering plates and fuel bowls these also need to be removed. Remove all needle valves and rubber parts from the outside of the carburetor. | ||
Try to preserve the gaskets if you can. A lot of the kits come with gaskets for several models of the same carburetor and using the correct gasket is critical. You can use the old ones to match the correct new ones. | Try to preserve the gaskets if you can. A lot of the kits come with gaskets for several models of the same carburetor and using the correct gasket is critical. You can use the old ones to match the correct new ones. | ||
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Once you have it torn down all the parts need to soak in your carburetor cleaning solution. I like to soak them over night. While they are soaking it is a good time to go over the instructions that came with the kit. These will go over the adjustments that will need to be performed. A good kit will also have a good exploded view to use as a guide. | Once you have it torn down all the parts need to soak in your carburetor cleaning solution. I like to soak them over night. While they are soaking it is a good time to go over the instructions that came with the kit. These will go over the adjustments that will need to be performed. A good kit will also have a good exploded view to use as a guide. | ||
Check all the parts to identify what you will be replacing. At a minimum all gaskets, needle and seat and the accelerator pump. Some will have additional parts as well. | Check all the parts to identify what you will be replacing. At a minimum all gaskets, needle and seat and the accelerator pump. Some will have additional parts as well. | ||
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