How much pressure is too much pressure that builds up in my gas tank on my 1986 Z28, 305cu with carb? Would it be ok if I alleviate the pressure by taking off the one way inlet valve that is above the rear axle on dr side and replace it with an inline air filter with and loop the gas line? This will let the tank breath in and out. Then I could disconnect the charcoal filter can and alleviate on less vacuumline.

 

What is your car doing that you need to vent the tank other then the factory did?