How can you tell if your car has a cam?

[holokosta]

So... Perhaps this is a complete newb question but...

There is a sneakin suspicion around my homestead and mechanic that my car may have cam in it... The reason we think this might be the case is because the car has had a fair amount of work to it, and when I had the opti replaced the water pump looked brand new as opposed to the opti, therefor saying that someone has already been down I that area of the motor. I have upgraded fuel system and injectors done and I'm getting a slight rumble at idle. Other than these things I would have no real idea. Is here anyway I can confirm our disregard our suspicions?