popping through carb on a iron duke

[fun80cj7]

I have a 1980 CJ7 I recently picked up and it has a 2.5 Iron Duke motor. it was running really rough, it has a Weber carburetor on it and a header, so I replaced all the vacuum lines, gas lines, Fuel filter, full tune up, ignition, water pump, hoses, and check the timing gears and I still can't figure out why I am popping Through my carburetor, any help would be very appreciated

 

[Bent]

Back-fire through the carb can be caused by a mixture that is way too lean. If the Weber was ordered for that motor it should have the correct jets. If it was on a larger motor, take a look at the jet size. Running a carb on a smaller motor requires LARGER jets. Less manifold vacuum means you need a less restrictive jet to avoid the excessively lean condition. Also try disconnecting the progressive linkage (if it's a 32/36) and just run it on the primary bore and see what happens. When the secondary opens, the drop in manifold vacuum may be causing it to go lean.