Cam too small, carb too big, converter too big, 36 degrees what? Initial? initial + mechanical? initial+mechanical+vacuum? What ignition setup? Stupid question, but did you make sure the plug wires are going to the right places and are not running parallel to each other?

Myself? I'd add a bigger cam. If the static compression is high and you run a small cam the dynamic compression can be high cause detonation. Double check that the carb isn't too lean, that'll cause detonation as well. Look at the plugs, if they are white there you go.