Replacement carb for 1977 L48

[Jeff Schuster]

Hi All,
The carb on my 'Vette has damage to the idle screw seat on the passenger side. Even bottomed, fuel still flows through the idle circuit profusely. I have decided to replace it. When I eventually rebuild this engine, I will likely do some head work and raise compression a bit. Perhaps a few other simple mods designed to raise the torque. In the interest of planning ahead, can anyone recommend a carb that will run smooth on the stock engine and also benefit a slightly more aggressive engine, too? Nothing too radical, just a little preformance boost is all I'm looking for.
Thanks for the help!
Jeff




Jeff's Garage

[Joe L.]

Re: Replacement carb for 1977 L48

Jeff-----

The idle adjustment screw seat problem is quite common. Many rebuilt carburetors suffer from it, too, since once the damage is done, it can't be "rebuilt out" of the carburetor.

For a 1977, though, I really don't see too many options. First of all, if you live in an area that has emission testing, you really can't modify the car too much. A change in the carburetor to another make/model, assuming that one was even available, will almost always throw you out of compliance on that basis, alone.

Also, even if emissions are not a concern, by 1977 emissions controls were pretty well "integrated" into the engine. This means that if you change a component like the carburetor, you'll have to change other things to make the engine run right. Then next thing you know, you'll be into wholesale mods and you might not like what you have when the "dust settles".

My recommendation to you would be to obtain as high a quality rebuilt carburetor for your specific application as you can find and one WITH A WARRANTY. I don't like commercially rebuilt carburetors; I find them to be a real "crap-shoot". However, at least with a warranty you can take them back if they don't run right and keep doing so until you get one that does. For your situation there really isn't anything you can do besides a rebuilt carb; the GM carbs are long-since discontinued and I don't think that there is any other new carb manufactured as a direct replacement.

[Joe L.]

Addendum

One other thought: if the carburetor that you have on the car now is an original carb (i.e. GM #17057202, 17057203, 17057204, 17057502, 17057504, 17057582, or 17057584 depending upon specific application), your best bet as far as preserving originality and value of the car will be to try to save it.

In that case, you might want to contact a VERY experienced custom carburetor repair/overhaul shop specializing in Q-Jets to see if they can do anything with the carb you have considering its problems. Some of the shops like this have developed innovative (and, often costly) repairs for valuable carbs. One such shop is Brad Urban's Carburetor Shop in Rancho Cucomonga, CA. Brad Urban, unfortunately, passed on quite some time ago. However, I believe his shop is still operating with experienced technicians using procedures which Brad developed. There are other Q-Jet specialty shops out there, too.

Keep in mind that even if originality and "numbers matching" are not important to you, they might be very important to whoever you might sell the car to someday. Even if you decide to replace the carb, if the current carb you have is original, you want to make sure that you save it and keep it for possible future use. It's worth a lot more than its core value on a rebuilt carb.

[Jeff Schuster]

Re: Addendum

Excellent thoughts... thanks, Joe!

[Jim T.]

Re: Replacement carb for 1977 L48

Jeff you asked for a replacement recommendation for your original. If you are wanting to drive and enjoy your planned performance enhancements you could use a Holley 650 #6210 spreadbore double pumper. I have used this carb since 1974 on my 68 327/350 and my 70 350/300. It was designed to replace QJets many years ago. It will bolt directly onto the manifold having small primarys and much larger secondarys.

[Jeff Schuster]

Re: Replacement carb for 1977 L48

Thanks, Jim!
I have heard mention of that carb before, and it is a option I plan to research further.
I appreciate your input!
Jeff