I had the same symptoms with my newly rebuilt engine. The problem went away after a couple thousand miles. Go to autozone and get a high tourque starter they are not much more $$ than a reguler starter there is a slight diferance in them but I can't remember (something about where the terminals are)? You might have to work with them to figure out which one is high tourqe I don't think there books list them like that. I have a heat sheild but that just covers the solenoid it didn't solve the problem when the motor was new. Also change the oil frequently during the break in period. Pete