Question on 69 Hemi Roadrunner Air Cleaner - vacuum hose connection

[AR67GTX]

I've been helping a friend with reassembly and de-bugging his 69 Hemi Roadrunner with 4 speed and power disc brakes. One of his supplier/technical sources he goes to for rare parts said for a power brake car he needed a two-port manifold fitting behind the rear carb on the intake. Of course the big port runs to the PB booster but the smaller (3/16" ID guess on my part) runs from the fitting to a fitting on the air cleaner base behind the rear carb and the fitting just opens into the air cleaner. To me it's just a big vacuum leak - although at least it's sucking filtered air. I reset the idle mixtures on the rear - primary carb to compensate for the additional air at idle, lacking any other idea or understanding of it's purpose. It's sort of like an idle air bypass - maybe?

Is this correct? should it maybe have a check valve on it? Is it really a form of idle air bypass? Is there something else that it should connect too?

 

[Kowal]

I think you need this. The plumbing is described in the Dodge service manual. This isn’t my car but it is the picture that I used to get started on plumbing mine.

 

[Kowal]

I think you need this. The plumbing is described in the Dodge service manual. This isn’t my car but it is the picture that I used to get started on plumbing mine.

View attachment 710828 View attachment 710829 View attachment 710830

“This” meaning the green capped vacuum valve.

 

[Kowal]

Here is mine. (I never bothered correcting the choke on mine, not using anyway)

 

[69hemibeep]

The small port off the intake goes into the green valve port pointing towards the drivers side. The small hose to the air cleaner goes to a heat tube off of the exhaust manifold

 

[AR67GTX]

He definitely doesn't have that little jewel. What is the exact term for it - I did find some reference to a "choke preheater"? Is that correct.

Thanks for clearing that up. I kept commenting this just doesn't make any sense.

 

[69hemibeep]

The little green jewel is adjustable as to how much vacuume goes to the distributor . If you are missing this just plug the small port on the intake......Distributor Vaccuum Control, w/Manual Transmission
w/170 Eng. - # 2843 299
w/426 Eng. - # 2863 739

 

[Fran Blacker]

Not right P/N but could be a superseded P/N? Not mine. Beware.
https://www.ebay.com/itm/NOS-MoPar-...217157&hash=item215172245f:g:8sIAAOSwCNlb9FQk

 

[AR67GTX]

Thanks. After $700 repro air cleaner base plates, $100 + dashpots, etc, etc, that is almost a bargain.

 

[Kowal]

The service manual

 

[Kowal]

The little green jewel is adjustable as to how much vacuume goes to the distributor . If you are missing this just plug the small port on the intake......Distributor Vaccuum Control, w/Manual Transmission
w/170 Eng. - # 2843 299
w/426 Eng. - # 2863 739

Agreed...I ran without it for a couple years, no big deal, only added it in the drive to be reasonably accurate in the engine bay. The valve does actually work, you can feel it sort of at part throttle Cruise.