Swapped out my 283 for a stock 350 crate engine. Had to pull it out to balance at 1800 miles. Nothing else changed or modified. Starts, runs fine, gets up to temp(180 deg.)while driving, after about 5 minutes it starts to bog, and then starts to backfire when ever I try to get into it some, and keeps getting worse. Will cruise, but nothing more. It was a year before it got back into the vehicle and restarted. I thought maybe it was running out of gas and causing a lean situation. Checked fuel flow from tank, new fuel filter, new pump. Carb looks clean inside. Up untill it starts to act up, it will do what ever you want, so I kind of ruled out mechanical issues. Other than the balance issue, it run fine before, and nothing has changed. I am running an Edelbrock Performaer carb, and Petronix in the distributor. If it was the carb, why start then. I knew I was going to tear it down, so I run a tank of Marvel Mystery oil thru it , and then topped it off and added some more. Can't imagine that would affect anything.Any suggestions are greatly appreciated. Thank you for your help.
