[Trevor78]

Haha I'm in Australia but feel free to have one! I picked up several junk heater boxes years ago, just for vacuum lines and retainer spares.

[GoreMaker]

Originally Posted by Trevor78

Haha I'm in Australia but feel free to have one! I picked up several junk heater boxes years ago, just for vacuum lines and retainer spares.

Oops! Yeah, you're too far 😂 I'll just use a pair of sealing foam layers to accomplish something similar

[Trevor78]

Those are all engine and emissions diagrams, the simple vacuum for dash controls come off the rear intake runner port.

Start a new thread, that sounds really messed up. Whoever carried out the carb swap obviously didn't know what or why they were doing it, which is nearly every carb swap.

403 olds intake vacuum checkvalve (2) by Ben, on Flickr

403 olds intake vacuum checkvalve (1) by Ben, on Flickr

[GoreMaker]

Originally Posted by Trevor78

Those are all engine and emissions diagrams, the simple vacuum for dash controls come off the rear intake runner port.

Right. All the heater box vacuum comes from that vacuum check valve, and gets distributed through the interior by the climate control unit.

Originally Posted by i4abuygto

I am trying to figure out the vacuum system as I do this. Perhaps someone can help me with what is necessary and what is not.

What you're referring to is the underhood vacuum system, which is completely separate from the heater box and climate control. In my case, I eliminated almost all of it, with the exception of a vacuum switch that sends ported or manifold vacuum to the distributor (depending on coolant temperature), the PCV valve (which goes to a dedicated port on the carb), and the charcoal canister (which j'ai goes to a dedicated pet on the carb). Beyond that and the heater box, I've blocked off all other vacuum because I no longer run a vacuum brake booster or any other emissions systems.

If you need info on the underhood system, you'll need to start a new thread in the Street Engine category of this forum

[i4abuygto]

Thanks guys, for your help.
I am not running any emissions either - 403 with better cam - headers - internals unknown but runs strong. Rear end has been upgraded to approx 3:25 gears. I just want to clean up the vacuum system so it is correct for what I have.
I will start another thread in the street engine section.
Thank you.

[Trevor78]

Some of those studs were threaded into the plastic of the box but if you snapped it then along with the nut was probably half eaten away with corrosion at that location. If part remains you could create a tube-nut sleeve, thread it onto the portion, thread a new stud extension into it with loctite. Then when tightening it all up just don't swing off it too much!