Trying to get the motor to stop backfiring. When it started we decided to rebuild the carb. Just rebuilt the carb, and still backfiring. Reset all the points on the distributor and found a wire that was going to the distributor terminal was broken. We fixed the wire, and I also bought a vacuum gauge and it is reading ~30. All emissions are still in place. It is backfiring at idle every so often but not through the carb, it is backfiring at the exhaust. It previously was backfiring through the carb prior to the carb rebuild. Any advice?