Carb Help Please
Thread Starter
Racer
Joined: Apr 2005
Posts: 423
Likes: 20
From: Ontario
Carb Help Please
Hi guys,
I am going to try to change the carbeurater on my dads corvette (its a 75) for him, while he is away at work for the week. The one that is on it right now has a fuel leak, and I have another one now that has just been rebuilt. Is there anyone here that could recommend a website that has something that could walk me through how to change it. Any help would be greatly appreaciated.
Thanks
I am going to try to change the carbeurater on my dads corvette (its a 75) for him, while he is away at work for the week. The one that is on it right now has a fuel leak, and I have another one now that has just been rebuilt. Is there anyone here that could recommend a website that has something that could walk me through how to change it. Any help would be greatly appreaciated.
Thanks
Race Director
Joined: Dec 2004
Posts: 14,968
Likes: 2
Its' not really that big of a deal.
The Quadrajet has 4 main bolts securing it to the manifold. You will probably want to get some tape and label where the vacuum hoses go. Be careful with the electric choke connector; on older cars they are brittle from the heat and will break.
You will want to put a backup wrench on the main fuel inlet when you take the fuel line off. And you should use a line wrench to bust that loose. Not necessary all of the time, but they can be tight and a regular wrench can round off the fitting. You will probably need the same thing on the rear of it for the brake booster line.
Be careful when pulling the clips from the throttle cable. They can easily become a "OH ****, where the hell did that go?" when you take them off.
Just take your time, take notes and you will be fine.
The Quadrajet has 4 main bolts securing it to the manifold. You will probably want to get some tape and label where the vacuum hoses go. Be careful with the electric choke connector; on older cars they are brittle from the heat and will break.
You will want to put a backup wrench on the main fuel inlet when you take the fuel line off. And you should use a line wrench to bust that loose. Not necessary all of the time, but they can be tight and a regular wrench can round off the fitting. You will probably need the same thing on the rear of it for the brake booster line.
Be careful when pulling the clips from the throttle cable. They can easily become a "OH ****, where the hell did that go?" when you take them off.
Just take your time, take notes and you will be fine.
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Race Director
Joined: Jun 2000
Posts: 10,008
Likes: 644
From: FL
Originally Posted by chris75stingray
there are plenty of screws that hold the carb together.its probably an accelerator pump.
Be careful with rebuilt carbs. They are rarely jetted correctly for your application and in fact some are completely screwed up. Saw this in person with several carbs at the recent "Tuning For Beer" stop in NE>
Drifting
Joined: Nov 2002
Posts: 1,665
Likes: 1
From: Ontario
Originally Posted by Mickman
Any help would be greatly appreaciated.
Don't adjust anything on the old carb - if the new carb has problems you want to be able to put the original carb back on and have the engine run as well as it did before you started this project.
How do you know the carb is a leaking fuel? Did you look in the intake after the car sat overnight and see wetness? If so you have to remember that the wet fuel you see in the intake may be the accerator pump shot you get when you open the throttle blades.
If you & your dad need to fine tune the rebuilt carb once you get it installed here are some helpful links.
QJet troubleshooting by Lars
QJet tuning by Lars
QJet exploded view
Race Director
Joined: Dec 2004
Posts: 14,968
Likes: 2
Originally Posted by chris75stingray
there are plenty of screws that hold the carb together.its probably an accelerator pump.
None that I can think of....
Perhaps you mean a fuel line.
Be careful with rebuilt carbs. They are rarely jetted correctly for your application and in fact some are completely screwed up. Saw this in person with several carbs at the recent "Tuning For Beer" stop in NE>
Yeah, those rebuilds are a pain. I'm still wrenching on the one that came with my recently purchased vette. I keep eyeballing the hammer on the work bench.
A lot depends on the rebuilder.
Putting in a kit is not rebuilding a carburetor. Neither is tuning one. Remanufacturing a carburetor is bringing the carb back to factory specs.
Thread Starter
Racer
Joined: Apr 2005
Posts: 423
Likes: 20
From: Ontario
Thanks for all the advice guys. Right now, the car has just been fixed after sitting on blocks for 15 years. We have 3 carbs( 2 quadrajets, 1 holley), all of them have something wrong with them. The quadrajet that is on the car now either has a vacuum leak, or a fuel leak im not sure. Right now it is adjusted enough so I can move it in and out of the garage, but it does not idle properly, and stalls alot. I am hoping with the new carb on, things will be better. My dad is the one that has all the knowladge about it, I'm just trying to do something nice for him and fix it while he is away at work for the week. I just dont want to end up doing damage or something, I am only 15 years old and do not have alot of knowledge about this. I have a general idea, but I'm not completly sure. Right now everything is on hold because of the carb. We need to adjust the timing and such and we need a good, working carb to do so.
Instructor
Joined: Feb 2004
Posts: 210
Likes: 0
From: woodstock ga
if it has been sitting for that long, chances are that alot of the origional gaskets and rubber seals in the carburator are long gone. If gas has been sitting in the tank for that long the tank will need to be drained. After you get the tank drained with fresh gas it usually take a little running, although probally not up to par with how you want it to run to, losten things up again. Have fun, you will definitly learn by both reading about how things work and just tinkering with them.
Thread Starter
Racer
Joined: Apr 2005
Posts: 423
Likes: 20
From: Ontario
scotty13, the carb that is on the car now is already rebuilt, but its just the vacuum/gas leak that is the problem with it. All the gaskets and such were replaced already during the rebuilt.
Last edited by Mickman; Jun 16, 2005 at 12:31 PM.
Le Mans Master
Joined: Jun 2002
Posts: 8,339
Likes: 24
From: I can walk to MA
Nice Father's Day present - unless things go bad.
Just don't mess with the carb that (kinda) works now.
Actually - per Lars - 90% of carb problems are actually ignition problems.
Maybe not the case for yours, but I'd try to get the timing
all set up before moving on to curing carb issues. This is the
way to do it. If the carb allows the engine to run - set the timing up first.
Your homework: download and read all the carb/timing/distributor
papers by Lars at Corvettefaq.com
Next: get Dad to read them, too.
especially How to Set Timing and Quadrajet Tuning
Link: http://www.corvettefaq.com/lars.asp
Just don't mess with the carb that (kinda) works now.
Actually - per Lars - 90% of carb problems are actually ignition problems.
Maybe not the case for yours, but I'd try to get the timing
all set up before moving on to curing carb issues. This is the
way to do it. If the carb allows the engine to run - set the timing up first.
Your homework: download and read all the carb/timing/distributor
papers by Lars at Corvettefaq.com
Next: get Dad to read them, too.
especially How to Set Timing and Quadrajet Tuning
Link: http://www.corvettefaq.com/lars.asp
Thread Starter
Racer
Joined: Apr 2005
Posts: 423
Likes: 20
From: Ontario
NHvette,Yes, we have already set the timing before but it still does not work properly. and in regards to the other carb, That was my plan to leave it alone so that if the new one doesnt work, i can always put on the old one, and still be able to run it.