Smog pump and parts

[gws34]

More info needed for smog pump/emissions stuff....

Enclosed is a photo from someone original 75 bronco with the emissions stuff still intact (forgot which user). I have been trying for a long time to get my set up and ready for daily driving in AZ. I think I am close.

first question. I got a new smog pump/thermactor from O'riellys a few years back. The only option was with the air bypass valve that bolted right to the smog pump, unlike to stock one that was remotely connected with rubber hoses. I think that is fine? But this air bypass valve has 2 vacuum nipples on it and the stock one only had one i think, which one do I connect to and do I just plug the other one like I have done in the photo?

Secondly I still have not found the Vacuum differential valve. Does any have the original parts numbers for this one or know where to get it?

Thirdly in the vacuum diagram enclosed, number 12 the vacuum solenoid?? Does any on know what this is? where does it go on the engine? Does anyone know the original part number for it?

Lastly, in the stock photo the one ported vacuum switch has an electrical connection on it, I believe from research this was only from 1975 but what does it connect to electrically? And do i need this if the 76 and 77 did without them? I have found one NOS but the guy wants 140 bucks for it so if I do not need it then great.


Thanks you all for your help.

 

[gws34]

Sorry I added color reference to the photo and then did not reference them.
Purple is the vacuum differential valve.
Green is the "stock" looks to be replaced I think original was metal, but I may be wrong, Air bypass valve. Also does anyone have an original parts number for this also?
Yellow is the eletrical PVS
Red shows where my air bypass valve connects. If I can find the remote one, does anyone know where to get the hose connection that would go on the back of the smog pump.

Again thanks everyone.

 

[gws34]

Found info on the vacuum solenoid from this forum, Yea!!!

From another post it is part # D2AZ-12A170-B

in that post they found that it was a non replaced part what do I do if I do not replace that part? will it still work as stock or do i replace with something else.

And it look like this is what the electrical connection on the PVS connects to but does it get power also? anyone know how this wiring works? looks like?

Thanks

 

[Rustytruck]

my guess the vacuum solenoid is to cut vacuum to the diverter valve on deceleration. so if you eliminate that you will hear popping in the exhaust when throttle closed running down hill and may cause an over lean condition with the catalytic converters.. 1974 didn't use that solenoid and the vacuum control module they did use didn't stop this condition. What a mess of vacuum hoses that was. 1974 also didn't have catalytic converters like the cars did.

 

[AC932]

I found a post that says the PVS electrical connection does go to the vacuum solenoid. I imagine that one side of the switch gets keyed power, the other side goes to the solenoid. You probably just connect the other side of the solenoid to ground. Apparently this bypassed air going to the exhaust manifold at temps >220 to protect the cat.

Here's the post:
https://classicbroncos.com/forums/showthread.php?t=296659


EDIT: It seems like the vacuum differential control valve does the same thing, just on deceleration as mentioned above. Heres a link to the patent:
https://patents.google.com/patent/US3955364A/en

And a link to a ebay listing for part no. D52E-9E441-DA and/or D5AZ-9E441-D Vacuum Differential Valve:
https://www.ebay.com/i/302159888430?chn=ps&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&itemid=302159888430&targetid=930729196022&device=c&mktype=pla&googleloc=9007881&poi=&campaignid=10456153627&mkgroupid=100467642661&rlsatarget=aud-622524042678la-930729196022&abcId=2146000&merchantid=8547114&gclid=Cj0KCQjw6575BRCQARIsAMp-ksO8jlxUqPgWR74fPaZm4W2uwup0OsQT6XxctLKpwHEDjTfLYslOQJ0aAnX9EALw_wcB

 

[AC932]

Also found a post that has some pictures that might be helpful for the location of this stuff:
https://classicbroncos.com/forums/showthread.php?t=241123

 

[gws34]

Thank you AC932. Yes I had found the post that you mentioned in your 5:26 pm response. It has been very useful, but I think is part of another problem I am having with the vacuum advance. If you look at the vacuum lines going to part #13 either way that ported switch is activated it is always giving full vacuum to the vacuum advance, so my idle was always high. I found another diagram just the other day and I think it fixes that problem. I will post it here When I get a moment, and after I check and see if it solves my issue.