because they suck... ok to be fair they work well on a street car, meaning not raced. If you want to go racing with them you'll need two. Not hard to tune, they just don't tune well. If you run a mild BB you'll need the 800 thunder.
I've won a fair amount of races in both Pro and N/SS with them. Doug
You ain't alone...
For carbs 'that suck', there sure are a lot of 'em out there kicking serious a$$...
