I just recently had an engine swap in my car. The orignal carbed 305 in my 82 blew a headgasket and was told it wasn't worth the rebuild. However since my car is a daily driver I needed an engine quick and the mechanics put in a 305 from an 89 caprice that had around 60,000 miles on it (yeah I know big improvement over stock). I don't think they really did anything to the engine though besides make sure it ran clean it up and drop it in my car. My car just really runs bad though, it seems to backfire a bit or just make a popping sound out of the exhaust if I hit the gas a little....and takes forever to warm up, plus there is a lot of gas smell. The engine idles at about 500 when it first turns on and it takes me a few times to start it up. I have no power at all either I figure my car might be running rich or something. What are somethings I can take a look at that I may be able to fix myself. Also the check engine light is on, but I figure that is because of the engine that isn't original.....but I was wondering if that could make my car run worse, the fact that the check engine light is on making the computer make my car run funny. I know thats a lot of stuff I wrote, but anything would help...I want to tweak with it a little on the weekend to see if I can improve anything instead of paying the mechanic to fix it.

 

Sounds like one or more cylinders aren't running.

Check your plug wires, the spark plugs themselves, and the distributor cap. Pull the codes from the computer, that'll give you some idea of what the Check Engine light is about.

 

Yup, prolly is what RB said.. my 305 did the same.