That might be it. There was a guy selling them on ebay rebuilt and said he would include some kind of what looked like a round shim that went in the venturies and restricted it to a 500
I saw someone talking once about some small pieces you could buy to de: tune a 600 down to a 500.
Anyone ever hear of this and / or know where to get them?
I think Maybe a 600 would do you better with vacuum secondary's. don't know what manifold you have but from my experience with mechanical secondary's need a taller manifold to really mix properly. But that's just me.
