Can anyone tell me what the vacuum fitting that is located at the rear top of intake manifold that has the small auxiliary nipple on the side is for? The larger hole in top of fitting is for the power brakes. It is a ‘68 engine in a ‘69 Road Runner 4 speed car. I will try to attach a picture.

This is what it looks like.
Thanks

 

It’s the small nipple on the fitting I’m asking information on. Anybody? Thanks in advance.

 

I don't know about the 426 but, I have a friend with a 68 Satellite. The 318 engine in that car has a similar looking fitting for the brake booster, the smaller barb is used for the HVAC controls. This was originally an A/C equipped vehicle.

 

Thanks dodgem880. My car is not a A/C car so don’t know if that makes a difference.