A friend of mine has an 84 Monte w/ 305 carb engine (4 barrel). Problem is it runs like s$&* It's been backfiring through carb and or exhaust. It bogs when you hit the gas and has been doing that before the backfiring. The carb was rebuilt a while ago which seemed to help a little and the timing was advanced which seemed to help too. Now it's running like this. Any suggestions about what may be the problem? Also when setting the timing there is a four wire harness behind the distributor. Does this make a difference with how it is running now. All suggestions would be appreciated.

 

The 4-wire harness should have been disconnected when the timing was set, then reconnected. Was it?

If not, there's your problem.

 

He didn't disconnect the harness when setting the timing. But what I don't get is how it ran bad before he messed with the timing at all. Could the carb be shot?