Webber decision: IDA or IDF?

[CompClassics]

I work with Webers regularly on both big block and small block down draft applications as well as other side draft applications. The IDF series are more street friendly as they have a progression circuit that the IDAs do not have. That being said there are modifications, some IDA manufacturers offer them as standard, that help the transition between the idle circuit and the “Go” circuit. There are also manifold modifications that help this also. I prefer the IDA series as that is what the cars were equipped with in period. The nice thing about the IDA series is the fact that they are infinitely tunable and can work on fairly small engines all the way up to big big block engines, you just need a competent Weber tuner. The other thing that complicated any multi-carb installation is the throttle linkage, the throttle linkage is the MOST IMPORTANT piece of the puzzle you can install, especially the rod ends and levers! One cheap sloppy rod end or one lever that doesn’t have the same movement geometries as the rest will destroy and or frustrate an otherwise good installation.