Ok the other day i pulled off a 94 ls head and put on a 2000 ls head and changed out a busted headgasket so i can pass smog. I think i may have or must have stretched the timing belt either when i put it back on or off. Everytime i line the gears up and crank perfect, the timing retards itself about a half of a degree everytime. ( i did the timing like 10 times to make sure) my idle is kind of rough, it tends to rev back and forth between 300rpms and 800rpms when warmed up. The car doesnt bog/die and the powerband is smooth through all the rpms when driving it, it just makes me a little concerned knowing my timing is not 100% perfect. thanks for any input/experience

 

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