Fuel leak

[Redlineshftr]

Hi I recently bought my first porsche. A 1970 911t. I cannot drive it yet because the right carb leaks fuel. I did notice that there is only gas at or below where the carb meets the manifold. The previous owner said when he drove it home it wasn;t leaking. But it sat for quite awhile in his garage and when he started it up one day he noticed the leak. Could it just be a deteriorated rubber o ring or maybe a gasket leak? thanks- Mike