Originally Posted by brenx
Putting a vac sec could be done provided you don't want to use the engine to it's full potential.
There is a good bit of truth in this statement, however, it isn't as if it is impossible to get the engine to run at its full potential, rather it just takes a lot more effort and tuning than a DP. It is probably worth the wasted petrol and headache to run a DP unless you happen to be rather gifted at tuning.
I've ran some very strong engines on VS carburetors and with the right bit of tuning and time on the chassis dyno, you can make them run very, very well. Better than a DP? Probably not for drag racing. Your engine needs a lot more fuel added when the green flag drops and a DP does this quite well. By the time you build up a VS for the race track that can be competitive with a DP, you don't really have much left but a DP with only one pumper and a tuning problem waiting for you at every different track you race at...if you travel around to different tracks.
For a hotted-up Cleveland, a DP is a good idea for anyone who will be taking it to the track. OTOH, a good VS is a good compromise that will save some fuel economy and run very well on a lot of engines. I probably would run a DP on any solid lifter camshaft engine where the cam was an F246 or more and consider a VS carb for an H238 or less. Here, a good used VS carb runs $25-30 US. Put a $25 kit into it and you have a great part for peanuts. Besides, you can't really use all of the power you can make with a stout Clevo on the street anyway, so you may as well save some fuel while cruising or out on the highways.
I've built VS and ran against DP and it isn't that difficult when you learn how to tune them, especially for changing track conditions. Is it worth it for a drag racer? Not in my opinion.