98 Cavalier Engines
 

Any help on this would be greatly appreciated. So the other day we were driving about 65-70 mph and my fiance went to downshift to pass someone and went from 5th to 2nd gear on accident. The motor revved really high and started making a really bad knocking noise. When we got home, I pulled the valve cover, pulled the push rods to see if maybe we bent one but when I rolled them on a flat surface they looked ok. So then I thought maybe a collapsed lifter. So put everything back together, started it, lifted the valve cover but didn't notice any of the lifters moving any different than the others. So worst case scenario I'll have to replace the motor again. If I replace it, what motors out of other cav's, sunfires, or even s10's will work?