so a friend of mine comes and asks me to help him with this 1991 mazda 626 4cyl 12v he just purchased with an alledged blown hg.... so i get to wrenching and all day im working on this car, once the head is off i take the hg and inspect t for heat spots, nothing. check the cyl walls, all fine. put on a new hg and torque everything down, button everything up and put it all back together. try to start it and nothing.... the previous owner over heated it pretty bad..... now my question to you mazda guys are, what the hell can it be??? ill pay if someone they can help me get my friends car running...

thanks in advance...

-pablo