Hi, im from washington and last June i purchased a 65' coup with a straight six in it. Ive been trying to get it started ever since. I re-built the carb and checked the gas lines and fuel pump. All were ok. One of my cousins owns an old duster and on his engin he has to have a cap over a hole in the top of the cover where the pistons are. On my engin im missing a cap that goes on the engin about 2-3 inches from the front of the piston block. I wondering if i need this "cap" for proper combustion to take place etc? Is this the case?