I didn't see those on my '78 when the throttle was off.

Bruce-

 

Where does that  advance port go to on the outside of the throttle body?  I must be getting a little leak from that, increasing the idle too much, so screwing the idle screw all the way  in doesn't get the idle to the right point.   I must have missed  closing that hole when the throttle body was being  cleaned & serviced.

It's the one that points toward the radiator. Vacuum from that front port should "T" to go to two places. 1) the distributor vacuum, and 2) the carbon canister control line.

 

I think I've got a spare throttle body in the shop. I'll snap a pic or two and label the connections when I get a chance.

I'm pretty sure that was the port I tested and found to have ported vacuum.  The one pointing toward the TPS switch was blocked when the BCDD opening was blocked off.

 

Plus, the PO must have re-plumbed the vacuum hoses from the manifold port.  That port had a Tee to go to the FPR, and the other to go to the distributor and (another Tee) for the carbon canister.  Similar variances were inside for the ventilation  vacuum hoses and blower motor.

Edited October 7, 20159 yr by TomoHawk

I finished blocking the BCDD holes, and I completely filled the BCDD cavity with JB Weld.  After installing, it worked fine, and I had the usual vacuum for the distributor.  The good thing about this is that I don't hear the sucking noise any more.  The noise sounded like sucking air through a straw, and was from having the BCDD valve removed.

Edited March 20, 20169 yr by TomoHawk

Some photos.

     

Edited March 20, 20169 yr by TomoHawk