My 87 with air conditioning ( works fine ) , has the larger of the two sized vacuum balls and I would like to replace it with the smaller one . It has the one port hose . Reading in a previous post that Acuth1 answered , would the smaller sized one have adequate volume of vacuum to run my A. C. properly ? How do you know one has an internal valve and does it matter ?

It does make a difference. If you have the larger one it means you have cruise control, the smaller one is used for non cruise vehicles.

Potentially, the smaller tank may not be adequate for an extended acceleration pull when the ventilation airflow is being directed to the upper ducts. Nothing will be harmed if it runs out of vacuum reserve; The airflow will revert to the lower heater ducts. IMO, it's worth a try if you'd like to clean up the underhood area a bit.

Bill

Bill

I Have Always Been Told, SIZE MATTERS

IT sure does, Big Blocks forever,Small Blocks are for those that DIY it.

:poke:Balls or blocks,:argue:

On mine their is [ 2] . One large one on the drivers side fender well. One smaller one located on bracket near a/c area..