so my car hasnt been running good, has over heated once just because i was going up a steep hill and that was months ago, but thought i could be the head gasket. so did the compression test, was only able to do one because the cheap autozone tester broke, but cylinder one came out as 98. My question is could a head gasket being cracked lower the compression that much? i was thinking piston rings but i friend said it could be, i do over rev sometimes. car has 128k on it the motor is a sohc non vtec zc

 

Get a different tester and do it again. If it broke after one, I wouldn't count on it being accurate.