Apologies in advance for such a lengthy post..;p My vehicle is a 1985 Z28 305 TPI. I'd like to leave off any unnecessary air/smog equip from my engine; however, I'm kinda stuck by not knowing just exactly how to do this (given, this engine was missing alot of parts when I began this project). I've done multiple (and then multiple) searches throughout the forums, but I'm still not entirely clear on what to do given my present setup. Presently, I have removed the smog pump from the block. I have also removed the heat risers from each of the exhaust manifolds and capped their respective holes using 1/4 inch flare plugs wrapped in teflon tape. The plastic air diverter valve which was mounted on the front p/s of the block has 3 circular fittings which I assume various hoses connect to. Two of these plastic hose fittings on the diverter point directly toward the rear firewall of the engine bay and the third fitting (on the diverter) extends downward coming out from directly beneath the diverter. I have two heater(?) hoses both of which come out of the p/s firewall which faces the rear of the engine block. One of these hoses is of a molded shape resembling that of a question mark and it is attached securely to the face of the firewall behind the block. This hose pretty much extends straight downward and then it elbows at a 90 degree angle (changing into metal) and connects to the radiator. The second heater(?) hose that comes out of the firewall extends nearly the same exact forward length as that of the plenum; but, (the last few inches of this hose) elbows off to the d/s and seems to be designed to fit onto the lowest of the three (3) fittings which extend out from the forward-most p/s of the plenum. From what I have read in previous forums, I believe this is correct. As the middle (p/s) plenum hose fitting resultingly connects a hose which runs back underneath the plenum (over to the d/s) and connects onto the charcoal cannister opposite the battery. And finally, the uppermost (p/s) plenum fitting attaches another hose which connects to a pcv valve mounted in the p/s valve cover. Ok, but this is where I get stumped. I see no other hoses in need of attachment within my engine bay. (Aside from a couple much smaller vacum hoses). What I don't understand is how I can successfully preserve the option of heat w/i this vehicle by properly sealing off the air diverter valve? I can find no other fitting on the radiator that will accept a hose should I attach one to the diverter and try to bridge a connection. It would appear that the first of the two heater(?) hoses I mentioned serves that purpose. I see no air control valve within the engine bay, much less any hoses that would connect to it. The only visible fittings that I still see as being presently un-used (aside from the three (3) on the air diverter valve), is: 1) The threaded heater hose fitting located on the front of the intake manifold next to the Coolant sensor. 2) The nipple fitting (extending downward at a 45degree angle) which is located on the underside-d/s of the front face of the plenum. Btw, I also replaced the original water pump on this block with a new one. In so doing, I left the the square, threaded pipe plug w/i the top of the new pump (the same as the old) since the old pump was configured this exact same way. I'd really like to do the TB bypass that I've seen mentioned in other posts. Unfortunately, I'm not sure what I need to do to even begin to connect a first thing to another. I do know that I don't wanna mess this vehicle up any more then its already obviously been abused and neglected by its previous owners. I'd like to do this vehicle the right way and minimize the possibility of experiencing any unsavory "horror-stories" resulting from this rebuild experience. Unfortunately, Haynes manual(s) leave sooooo much to be desired. I'd really appreciate any help that anyone can give me on deciphering this particular engine set-up, given the objectives I'm trying to achieve. Thanks in advance for your time and consideration.

To bypass the T/B is simple, Take the hose that comes from the firewall and runs along the top of your RH valve cover and remove it from the T/B. Next remove the hose from the T/B to the front of the intake. Now, take the first hose you took off the T/B and see about what shape it would need to be to hook to the front of the intake. Go to your local auto parts store and see what they have in the size and shape you need (you can splice it to your existing hose in a straight area with a hose splice and clamps) also get 2 rubber pligs to fit over the now open hose fittings on the T/B to keep trash out of it.

The air diverter valve can just be removed and the pipe going to the CAT from it plugged up (you already plugged the injector lines going into the manifolds)
And if you want to get rid of that diverter valve, I'd be glad to take it off your hands.

if I do away with the air diverter altogether...wont' that render the vehicle to be without an operable heater?

I certainly wouldnt mind letting you take the diverter off my hands...no problem at all..

My only concern would be having a vehicle without any heat.

Perhaps I'm thinking of something else..hrm (?)

Lemme know, either way. If I'm mistaken, then you're welcome to it.

Thanks again for your prompt reply!

No, the diverter valve is just for the A.I.R. pump, you are thinking of the heater control valve which you shouldn't have anyway.
On the diverter valve, the port that points down went to the A.I.R. pump, the two that point to the firewall, one went to the manifold tubes and the other goes to the cat. converter. No coolant went into that valve at all.

If you route the heater hoses like I described you will still have heat but the coolant will no longer pass through the throttle body.