I think only the later cars have the valves that control vacuum...
Mine has the vacuum plumbed from ported and non-ported vacuum to the different sides of the diaphram.
At least that is what my car has (not that it matters as my vac diaphram does not hold pressure....).
If anyone has an early car (stock) - it would be good to confirm....
If you see http://www.dagsites.com/emissions.htm
There is nothing listed for a 1970 but you can see the progression in complexity from '72 through to '74.
Mine has the vacuum plumbed from ported and non-ported vacuum to the different sides of the diaphram.
At least that is what my car has (not that it matters as my vac diaphram does not hold pressure....).
If anyone has an early car (stock) - it would be good to confirm....
If you see http://www.dagsites.com/emissions.htm
There is nothing listed for a 1970 but you can see the progression in complexity from '72 through to '74.