My 914 has a 1.7 and was rebuilt with domed pistons and a web cam for carbs...I don't know the specifics on the cam right off but can ask my mechanic. I am running a 32 36 progressive which I know none of you like and am going to switch to dual 40 carbs. How much in horsepower will I gain if any? Thanks

If everything else is stock, you may have 80 hp.

This might help:
http://www.914world.com/specs/engnumbs.php

I'd say 80 - 85 is a good guess ...

Do you know how much I will gain by going from a single carb to duals?

The biggest gain will be in driveability. Off the line performance will be dramatically increased. Over all HP may only gain 1-2 HP. But down low you will notice more power off the line. Cold start may improve as well. The single webber also has a flat spot when the secondary opens. This will be eliminated.