i had a rebuilt 400 install in my car it sound ok at first but the car had no power so a couple of mechanics told me it was a carbuator so i took it to a garage that deals with carbuators and they adjust the choke because the carb has a electric choke and the motoe has a manuel but anyway their now is a rattling sound in the back of the motor it almost sounds like a rod knock is their something else it could be the guy who install it said their was no compression in number 1 cyclinder and he lash the values any help would be apreciated thank you