Can bad vacum cause a tick?? or ping sound ??, all my vacum lines are dry rotted i think its time to replace. Truck revs fine no backing or anothing i was told that its one of 2 things bad cam or bad idle. I dont think it's the cam motor was rebuilt professionly and only has 111 000 km on the oringal 305. I cant afford to buy a 350 and have it rebuilt at the moment.