I have a carter afb 4131s (575-600 cfms) specs show , that I have gone thru and rebuilt . I have a full throttle surge that comes on around 5000 rpm when the secondaries are opening up. (just when you are getting into the secondaries) . everything is fine on the primary side. no issues there. also no issues with timing , distributor or any other electrical components . I just recently took off a holley 650 dp that worked just fine at full throttle. thinking that dp was just a little too much . I probally had this carb off the car and gone thru it dozen times but with no luck getting that surge to go away. here are what is in it now . step rods 16-404 brown springs and rod tall covers. .. tall jets in pri 120 - 352 have no clue what this is in orifice size. can't be 52. rear jet 392 . I went thru this carb ,soaked it, blew every orifice out a dozen times , set the floats to stock specs, new needle and seats. everything appears good there. squirters are working fine . this particlular carb does not have any secondary weights or butterflies in it all oem components. all gaskets are aligned up with the correct holes every where. since the floats are set to stock measurements , do you think that going up in the secondary jet may cure this ? or maybe setting the floats different ? I just don't know where to go from here.The engine is a fresh rebuilt 273 commando..... one step up in cam and headers new mech fuel pump . That's it. where should I look next?