I just picked up an 89 Jimmy. I went to get it smogged today and it failed because the ignition timing is too high at 800 RPM and they said it should be at 600. Is there anything I can do to fix this or do I need to take it to a mechanic? Also the engine has been replaced with a 383 if that matters

 

Is it carbed or does it have fuel injection.If its carbed you need to lean your air fuel mix.You can adjust the timing also.Need more info about the year of engine and if and how its been modified.

 

pretty much all i know is that it is still throttle body injection like the original 350 and it has vortec heads. i probably should of got more info on it when i bought it, but i needed a vehicle right away so i bought this one. and it runs amazing. just this one thing i have to figure out

 

Are you in Oakland, CA? I thought they had strict rules about engine swaps...

Anyways, the ignition timing is a relationship between spark and pistion position. You said that it needs to be at 600rpm vs. 800rpm, that is a idle setting.

My $0.02 is take it to a mechanic.

 

Yeah California. As far as I know engine swaps are fine, just can't put a carbureted engine in a vehicle that didnt come with one.

 

You can advance the timing which will increase the idle speed.You have to plug or disconnect the computer cant remeber which hopefully some can help with that.If its not a timing issue it could possibly be tps.