I'm having a real bad lean problem with the 5200 holley I just put on my truck. It runs great on the primary but, backfires through the intake when the secondary opens. I just went through the dizzy new points, condenser, cap, rotor, plugs. The vacum and dwell are good, the vacum advance is working, and the timing I've ran from 4btc all the way to 12btc. I've done quarter turns on the air/fuel screw from a turn all the out. The sweet spot is about 3-3 1/2 turns. Still the same so I think it's got to be the jets. Anyone got any insight or suggestions??? Right now it's running a .60 primary and .50 secondary. Oh and yeah I even rechecked the float on the brand new rebuild I got from Langdon's. You never know ;-)
