Back to basics with my 86 305

[Sovereign]

I want to remove what's left of the emissions components on my truck. What's still present is broken switches and sensors, dry rotted vacuum hoses, and hoses not even connected. Instead of arrogantly ripping it all out sure that it's not needed, I figured I better ask what needs to remain.

So, does any of it need to remain? I plan to keep vacuum advance, cruise control, AC, PCV, and would like to keep the charcoal canister to keep fuel vapor odor under control.

Looking at the schematic sticker on the core support, it appears I can remove all of the valves associated with the air pump, EGR, and heat riser valve. Is this correct?

What is the tip in vac switch on the firewall and can it go?

Is it possible to keep the charcoal canister functioning without the valves?

What is the distributor delay valve and can it go? I've only had older engines with vacuum advanced connected straight to the valve on the distributor.

What should I do with any electrical connections that I remove? Without a computer, there are no fault codes to be concerned with. Are there any functions that would be lost if I remove the tip in switch for instance?

I appreciate the guidance.

Thanks

[Dead Parrot]

If you still have the OEM air cleaner, keep the THERMAC system as well. Speeds engine warmup and helps prevent carb icing during cool foggy weather.

You may want to look at earlier charcoal canisters if you have a 80s setup. Some of those were one hose to tank(s) and one to a T in the PCV hose. (at least from memory from when you could still find a lot of squares in salvage yards. My 75 didn't have a canister.)

If you have AC, you need a hose for the vacuum controls.
Many auto trans need manifold vacuum for proper shifting.

Verify that the heat riser valve is open with zero vacuum.

[Just call me Sean]

There shouldn't be any valves on the charcoal canister. The one on my 93 doesn't have any and it's fuel injected.

[geezer#99]

Originally Posted by Just call me Sean

There shouldn't be any valves on the charcoal canister. The one on my 93 doesn't have any and it's fuel injected.

If you translate his terminology then he likely refers to vacuum ports as valves.

When someone enquires about removal of possible emission controls I always wonder what they need to pass smog tests in their area.

[Just call me Sean]

Originally Posted by geezer#99

If you translate his terminology then he likely refers to vacuum ports as valves.

When someone enquires about removal of possible emission controls I always wonder what they need to pass smog tests in their area.

I assume no testing, like here.

[Sovereign]

No emissions testing here. The cat is no longer on the truck and I have no idea how long it's been gone. Truth be told, I barely drive the truck. It's my toy and project car. I'm doing this to hold me over until I LS swap the truck. I'm hoping to clean up the engine bay and investigate some running issues. With the system not 100%, I figured it would be easier to just remove it the rest of the way.

The valves I was referring to with the charcoal canister are the ones on the engine that the charcoal canister tees into. I don't know if those valves actually affect the canister's operation or not. If not, great. That certainly makes life a little easier.

Thank you!

[hatzie]

You can keep the EGR system without any performance problems or cap it off.
The THERMAC system is worth keeping for those high humidity 50°-75°F days in the fall and spring when the throttle can ice up.
EVAP is well worth keeping.
PCV is worth keeping if you don't want to deal with the engine turning into an oily lump from seepage.
The Vacuum advance runs through the same thermal vacuum valve as the EGR inhibit. Probably worth keeping it as is... including any inline delay or residual valves. You can run without it but it won't perform better and might not perform as well as it does now. One of those "If it works. Don't fix it." things.
The air pump is up to you. It adds air to the exhaust to aid the catalytic converters in doing their thing. Subaru and Honda used a pulse reed valve on the exhaust hooked into the clean portion of the air cleaner rather than a pump if you want to get rid of the air pump. If you have no catalytic converters it's window dressing.

For those that say the EVAP can doesn't have a valve that's not correct in most cases
The 60's - 80's EVAP charcoal cans usually have a vacuum actuated valve to open the can to the purge hose. The valve(s) is/are connected to a ported vacuum source on the carb or throttle body. Unlike modern EVAP systems these cans don't have a vent valve that engine computers use to test the EVAP system integrity. The 1980's setups are unnecessarily complex with multiple vacuum valves on the can in some cases. If it's working I wouldn't mess with it.

Most 1970's EVAP cans had these three hoses.

1. Valved purge to a Tee in the PCV hose or directly to the manifold. Usually 3/8" hose.
2. Vapor recovery line to the tank(s).
3. Purge valve actuator on the can hooked to a ported vacuum source (above the throttle blades rather than below) to control when the engine vacuum sucks the fuel vapor out of the charcoal.

[SunSoaked]

^^^^^^ what he said.

My 85 had 5 hose connections on it. I converted to aftermarket EFI and ended up with ports on the cannister didn't need. One day at the junkyard I was looking at a 88 burb and noticed it only had three ports, due to being TBI so I snatched it and lived happily ever after.

[Sovereign]

Any reason the six hose unit on my truck couldn't be converted to do the same?

[Just call me Sean]

Mine only has two hoses.

[hatzie]

Originally Posted by Sovereign

Any reason the six hose unit on my truck couldn't be converted to do the same?

None

1970's Corvettes along with the B & F body cars used three hose EVAP cans.
Gets rid of a lot of unnecessary spaghetti under the hood.

If you ever worked on an 82-84 Subaru or Honda or the early Dodge Caravan Plymouth mini vans and Aires K cars with the Mitsubishi engines you'd laugh at the folks complaining about the 1980's GM Vacuum hose spaghetti.

My 1980 Celica GT and 1979 Datsun 210 were pretty awful too. The late 1970's through the 1980's Carbureted Japanese cars and the carbureted Mitsu-Chryslers had steel vacuum hose manifolds that routed the spaghetti around the engine bay. The 1984 Fuel injected Subaru Turbocharged engines were almost worse. Scary stuff if I'm being completely honest.