318 rebuild noise

I have seen and heard this from many who ruined their motors installing the timing cover. The two lower bolts on the drivers side of the cover I believe could be your problem. If you put to long of a bolt in one of these holes it pushes through the cylinder wall, and the skirt of the piston comes down and hits it. When you loosen it up the noise will seeam to get less but it will still be hitting the cylinder wall which is now shot. If you would go to put water in this motor and this is what happed you will fill the oil pan with water. This is a common mistake on alot of do ot your self guys that either never had the right bolts or just through everything in a bolt bucket to sort later. The bolts are specific to their holes , I have seen guys take the power steering brackets off and use the same bolts they took out without the use off the bracket or washers, the bolts were to long and they ruined their engine. Good luck I hope this isn' the case. Drop the oil leave the plug out and fill the block with water. Wait alittle while and see if the water starts seaping out the pan. If so , this cannot be repaired with out sleaving the block .Sealers will no work hear because you have alread egg shaped the cylinder