Tim:
I have a .72 that can't make up its mind if it likes the tubing installed or not. The magic number seems to be about 5". If I go any longer I have to insert a piece of hard tube in the end and cut it at an angle. Does not kill the engine, but it just seems to lose several hundered rpm's. First indication that the tube is too long (restricitve) is the oil slobber out the tube goes away.
Ed M.