How do you measure the size of a carb?

[grannyknot]

My set of triples are OER/SK's (Weber clones with a few refinements), just wondering how it is determined that a set is 40's, 45's or 50's. Is the measurement taken at the narrowest point near the butterfly valve or at the front where the air horn attaches?

I ask because I would like to purchase a set of air horns and those cool SS mesh filters that snap over top.

Carbs Unlimited (thanks Zedyone_kenobe) sell them as well as Peirce Manifolds but they all seem to come from one maker. They say they filter down to .009" - is that good? Is that enough or is it only for car shows?

I love the look, but I don't want to sandblast the insides of the engine for looks, I want the engine to last a long time.

Thanks,

Chris

Edited December 23, 2012 by grannyknot

[LeonV]

Measure at the butterfly end, if the number isn't casted in on the bodies somewhere. I haven't tested them myself, but the mesh filters aren't recommended. They are restrictive, at least more so than the bigger K&N-style ones. Again, how restrictive, I don't know.