Carb is rebuilt but a couple of questions. I’m snug on the main 4 bolts but i keep leaking between the carb and the manifold gasket once the engine is off. Also is it normal for fuel to come out the top of the accelerator pump? I have a 1978 l48 4spd. I got the rebuild kit from carb doctor.

 

First thing I would do is put washers underneath the front two mounting bolts. Installing them without washers can mar the surface of and warp the airhorn as you tighten them.

Do you have a part number on the kit you used? Did you make sure to use an ethanol resistant accelerator pump? Did you make sure the gaskets line up perfectly from what came out of the carb? Does sit appear that anyone has been in the carb before? Lastly, what did you set the float level to?

 

You're leaking fuel past the needle & seat and have no fuel level control. You either have poor quality parts in the rebuild, a bad float, incorrectly set float, or a sticking float. The leak at the gasket has nothing to do with a leak at the gasket - you are dripping fuel out of the main discharge nozzles after shutdown, and the fuel is "wicking" out at the gasket and coming out the pump hole. Simply put: You have a poorly "rebuilt" carb that likely has more problems than what you have yet discovered... It needs to be torn down and properly set up with good parts. And where is your PCV hose..?

 

I have to take the carb off because I forgot to set the float level when I put a new one in. I’ll install some crush washer when I do. It’s carb doctor ck0145 and they said their accelerator pumps are ethanol resistant. Also found this gasket not sure if it goes under the spacer or between the carb and spacer

 

I forgot to set the float level when I rebuilt it. Didn’t even think about it. is there an easy way to adjust it?

PCV is another issue. Po removed it when he swapped valve covers to the wrong ones. I’ll be fixing that issue in a couple of weeks.

 

I have it adjusted now. I’ll have to try tomorrow. According to the rebuild manual it says I should be at 15/32. I got it to 14/32 (7/16) which also seems high still though. If it still leaks I might adjust it to 17-18/32

 

Best option right now is to send Lars an email and ask for his Q-Jet papers on setting up and tuning it. Reference your thread here so he knows where the request is coming from.
<v8fastcars -- at -- msn -- dot -- com>

If you really want top performance, consider sending the carb to him for complete rebuild and fine-tuning. What you get back will be top-notch and ready to bolt on.

 

thanks I’ll send him an email.

 

Do yourself and your pocket book a favor, send a bunch of photos to Lars of your carb. He will advise you on whether your carb can be restored. If your carb has been butchered, Lars will see it in a second. I always say that sending my Quadrajet to Lars was the smartest thing that I did for my C3.

 

It is good to try new things. You learn more by failure then success. Hope it works out for you,
I believe that gasket goes between the body and the bottom plate,
Use flat washers for the front 2 bolts. The crush washers will dig into the metal.

 

thank you

 

Hello again aaronjoshua92!

You have been given some great information regarding carburetors and from some people who know how to make the carburetor "Right" again.
Over the decades I have tried my hand at rebuilding my carburetors but occasionally find a minor glitch here or there after I re-install it. I am NOT a professional carburetor specialist but I know enough to recognize that there are times when it makes sense to hire a professional as this might save you dollars in the long run.

Lar's can bring your carburetor back to New condition (and perform really well) after a "Real" rebuild and get it set up on a running engine before returning it to you. If I were using a Quadra Jet carburetor he would be the man to rebuild it. I regularly learn lots while reading his responses to questions on this Forum. Questions like yours.

As far as I am concerned no car should leak raw gasoline anywhere. Seeing gasoline coming out of the accelerator pump is NOT a good thing. That makes driving the car a "No-Go" in my world, because it needs to be fixed before a tragedy occurs.

If it is an Edelbrock Carburetor then it likely means excessive fuel pressure caused by a faulty float or hardware associated with it. If it is a Holley, then you could be leaking gasoline through the accelerator pump's diaphragm and out the Accelerator pump housing. These are my "guesses" and they should both be easy fixes unless the carburetor has lots of miles on it.

As far as the vacuum leak under the carburetor I would put a couple gaskets together and coat them in grease before putting them on the intake below the carburetor. Just a slight covering of grease, don't use too much. The grease on the gaskets keeps them from sticking, and helps seal the joint slightly better. Another reason for vacuum leaks are broken base plates on the carburetors, it was very common to find them with broken bases from people trying to make it seal "better".

Over many decades I have accumulated several carburetors that all work on my engine combination. Take the good one and have a professional rebuild it for you. Just be sure that the person who rebuilds your carburetor knows that the carburetor is for use in a Corvette, and knows the tricks to make it work the very best it can. And Ethanol proof...

 

You do not want crush washers under the hold down bolts. You want plain flat washers.
Set float level to .300". Not the 7/16" you have mentioned - that's WAY too low.
Take that gasket shown in the photo above and throw it in the trash - that is not the right gasket for a '78. Use this gasket only:

The pump you have installed is not the best, but it's not your current problem - your problem is that you have failed to pay any attention to setup, specifications, and adjustments.

Lars

 

you are not wrong lol. I didn’t put that thin one in, I have the 1/4” spacer one in.

 

It's not a "spacer." It's the carb base gasket.

 

send it to lars

 

The Quads I have rebuilt over the years, 2 common things I have found. The float starts acting like a sponge causing the float to becoming heaver causing overflow problems. The second problem would run across is between the top section, and second section where they come together, In the middle there is a small expansion plug that drops out of place causing flooding. The rebuild kits from years a go would have a small epoxy kit, and a sponge looking cover you would slip over the epoxy and plug keeping it in place. I found rebuilding the quads one of the easier carbs to rebuild. GM used that carb on a lot of their cars. Ironally I have a quad in a box at home off a 77 Coupe de Ville. I rebuilt it it years ago, and never used it. All this is my experience.

 

Update:

I adjusted the bowl to 16/32” (1/2”) and started it today. No fuel leaking after shut down and from the pump rod. Thanks to everyone for the advice. I still need to adjust the fast idle and air/fuel mixture screws. I’m at about 1100 - 1000rpm when first started and around 550rpm once it drops. I’m going to take care of a few other issue first like valve covers and pcv before I adjust those.

 

That's really low on the float, and will not produce the best throttle response. I recommended a good setting for you in my post above, but I guess you have a better idea...

 

Like Lars said I would change it to the spec of .300”. If you’re getting fuel leaking out with a higher float level then you have other setup issues that need to be addressed.

As for your fast and curb idle speeds, they’re very accessible screws that can be adjusted in as little as 30 seconds. 1,300 for the fast idle and 800 without the car in gear are pretty good specs.