I have two 40 year old snowblowers with Tescumseh engines, one a 7 horse power, the other a 6 horsepower. Can anyone tell me what RPM I should set them to the best balance between throwing snow and long life? What are the maximum safe RPMs for the engines? I had an engine that went to a high RPM because the governor failed. Someone said that the high RPM could have stretched the connecting rod. What is the likelihood of that happening? How would it affect the engine operation, assuming the rod does not break? Thanks for any responses.