You can get light weight springs around 4 ounces up to 12 ounces or there abouts. these help control how much the the needle lifts up. the heaver the spring the the richer the mix when you open the throttle.

Hey steveo wat exactly is invovled for a weber to handle boost stronger gaskets ?

whats this SU book called?

think i might need to expland my library collection to a total of 1 books

other then the cange of postition of the carby not a great deal.Stronger gaskets aren't as neccessary in 'suck through' than they are in a 'blow through', due to the fact that the carby has to hold more pressure.

The 'suck through' set up is much easier, because the carby doesn't require any major modification seeing that theres only air flowing through the carby.The main drawbacks are that the fuel-air mix must pass through the turbo. Since fuel is denser than air it will tend to separate in the turbo and puddle up. Don't expect instant off-idle throttle response. The turbo also becomes less efficient because it has to pump this heavier fuel mixture, and it is trying to do it's job after the carb has already caused a pressure drop. You basically have the carb causing a pressure drop and the turbo trying to increase the pressure. The efficiency losses translates into a hotter fuel-air mix in the engine which limits the boost you can run and your power.

The main reason i prefer an SU over a webber is because the SU is so simple and heaps easier to tune, and the results are just as good as each other.Webber has to be jetted correctly