Hey, I just bought a white 77 Corvette with the L82 engine (for only 6K, good deal i think) , but ive had some problems with the fuel mixture. My mechanic told me that the floats are sinking a bit and its causing the car to run very rich. Im not sure if its related, but when i start it up and its cold, the car lags when i push on the gas, almost stalling. Also, the gas mileage seems to be suffering (probably from running rich). All confusing stuff because this is my first carberated engine. So here is the major question, i am able to buy a new edelbrock carberator, but im not sure what the differences are between them. Could someone explain what are the benefits from going to a 600 CFM, or a 650 CFM, or even an 800 CFM? Horsepower gains from extra fuel? or just more capability. Also, would getting a K&N air filter help me performance wise? just trying to learn about my sweet vette, info would be appreciated.

 

No reason to buy a new carb, fix the one you have. Your man told you what was wrong, sounds like you need a kit with floats, well under $100. Doug Rowe has a very good book on Rochester carbs, get that and a Shop Manual for your year. Ask questions, we got answers.
The numbers you are asking about are the flow numbers in cubic feet. The carb on your engine will do wonders with a fresh tuning. The numbers are capability, not a garontee, the carb will only flow what the engine can pull thru it.

 

if you have the original quadrajet on the car it may be a good idea to fix that carburetor. Edelbrock at one time sold a Q-jet but no longer sells them, the carbs they still sell are both performer (AFB)and thunder (AVS) carbs which are square bore carbs that will not bolt onto the stock manifold without a adaptor plate.

If you choose to use a edelbrock carb a 650cfm thunder is a good carb but a quadrajet is better for most applications.

i do not think i have seen a float "sink" in a q-jet built for a 75 or later corvette, the floats used before 1974 did have problems that were fixed after those years. you may want to get a second opinion to be sure your problem is not tune up related (ignition timing etc), if it is the carburetor rebuild or have YOUR carb rebuilt do not buy a factory rebuilt.

good luck and have fun with your new toy henry @ oles carb

 

if you are like me and have had little to no expieirience working on carburetors, then rebuilding it doesn't help much. When i finished rebuilding my carb it did help it alittle but it was just such a hassel have to figure out what every little piece is, which led me to buying a new carburetor(i even went one step further and built a new engine) which also led me to clearance problems and just having the headache of things not fitting the way they should.

Both sides have their pros and cons. Rebuilding your carb is good if you know what you are doing or atleast know more than i did because your engine is designed to run with that carb. But a new carb could be the way to go if you are like me and didn't really get much from the rochester shop manual, and caused me to not understand what certain things were or what the instructions were refering to.

i suggest getting the book and looking through it and seeing if you can understand what they are talking about, if you do then rebuild the carb. but if that stuff seems over your head, i'd suggest just bite the bullet and get a new carb.

 

Thanks for the info and ideas, im going to get the manual and take a look, ...ill see what i understand. Personally ive always been interested on learning how to work on older cars, so im going to probably give it a shot with a carb rebuild and then get a tuneup. Im off to find the book, but im still curious about the k&n air filter on carberated engines, does it help enough to buy one?

 

in my opinion an air filter is an air filter, put that money towards the book.

 

A KN filter in this case should be concidered a fine tuning change, get the other stuff fixed up, then deal with that.

 

If it is the original Quadrajet then I would suggust you do some research and find a reputable carb rebuilder in your area.
It will most likely cost you less than $150 for a proper rebuild... no need to throw away money on a new carb and possibly an intake manifold that will accept it.

There must be someone in your area that rebuilds carbs, just do a little research

If it is a Quadrajet and your mechanic said the "floats" (Plural) are sinking then I would guess he has limited experience with the QJ as they only have one float.

Please let us know what carb and intake is on your car. (Pictures would be great)

Welcome to the forum!

ps: this is what a Quadrajet looks like in case you are unsure

 

If you want to learn, go for the rebuild! A kit costs around $25 go for Echlin...its what the Guru Lars uses!, a new nitrofill float is $11 a new choke pull off is $22 a new fuel filter $2...not too much at all!

Get the book, pull it apart but take pics ( thats what I did so I could remember how it all went together ) The link to my 52 tear down pictures is here.
http://s46.photobucket.com/albums/f1...own/?start=all
If you scroll down to the last one and click it, it will start the slides in the correct order.

Clean it up, replace the parts and give her a whirl...you never know, you may suprise yourself.

Bob, How did you get your Q-jet looking so damn purdy?

 

Thanks Jotto... But I diddnt do it
I paid a local shop $40 to glass bead it, coat it and re-bush the main throttle shaft.
Then I bought it home and rebuilt it.
Runs great.

 

Very nice looking carb job. I didn't know a local shop could do that type of plating on the body.

 

Thanks for the photos jotto, very helpful, im going to start looking around and doing research on local places to maybe get a rebuild, ill try and post some pics

 

You need to find the right shop!
This is a small father & son shop and I was lucky to find them
They have been very helpful to me
Sometimes Ill trade an old core for some parts I need, jets/rods/power pistons, ect:...stuff like that, ya know!