Absolutely!!!
Some folks will recommend using an o-ring the same size as the intake manifold stuffed down into the carb spigot (mounting hole) to seal the intake.
I personally cannot recommend this in any way, shape, or form. Using the wrong type of rubber that the o-ring is made of can cause the o-ring to swell, get soft, and eventually get sucked into the engine.
When in a pinch, I like to use a product called Seal-All or RTV silicone black or copper.
Some vendors also sell a intake manifold with a groove machined into it to accommodate an o-ring. Check out Pirate Cycles for one. IMHO this is the only reliable way to o-ring a manifold, and it is also the best way to seal the carb mount to the manifold.
If you are skilled with a hack saw, you can cut your own groove in your current manifold and use an o-ring from a kit sold at Harbor Freight. Just be sure to get the correct rubber that is gasoline and oil resistant. It is called Buna-N. Silicone o-rings will also work if you can find them, they usually are a light blue color.