[scott70]

Originally Posted by Cliff R

1970 factory Q-jets do not have a vacuum port for the distributor, at least not a direct one.

That year they were using transmission spark control of some sort, which didn't work well then and most of those components were removed shortly after the cars left the dealers lot.

Those parts are pretty difficult to come by these days if one is trying to put one back to "stock" for a restoration project. Can's imagine anyone would want to use it.

These days I get a LOT of requests to add ported vacuum to those carburetors and a select few others that didn't come with it. Just had one yesterday where the owner was unable to get the idle speed below 1100rpm's with the throttle plates completely closed unless he unplugged the Vacuum Advance from it's manifold vacuum source.

When ported vacuum is added correctly, like the factory did it we get FULL MANIFOLD VACUUM to the distributor with the slightest movement of the throttle right off idle. At that point the only real difference between manifold and ported vacuum to the distributor is no timing added idle and coasting with ported. In ALL other scenarios they are the same, even though some self proclaimed distributor tuning experts will try to tell you otherwise.......

I guess I should of asked you add one back when you rebuilt mine.