Bought another k5. Smog/Vacuum line removal question.

[shadowwalker_02]

My buddy picked this up recently and I was able to wheedle him out of it. It's a 85 silverado edition 305/700/208. The white one, the red one is my 78 k5. All the windows and doors work, inside looks cherry minus 2 things and the best this is no rust at all. However it also looks completely stock in the engine bay. It even has working ac! Not that I use it but it's nice nonetheless.

Before I go head first and start tearing all the unwanted smog/vacuum stuff out, is there anything i need to be aware of? I don't want to mess something up and have it not run. Any paticular thing I need to be aware of? It looks like it has cruise control that I will be removing.

The best part about this k5 is the awesome dashpad cover. The "Sad Sack Blazer"?

The smog stuff. I'll have to get a better pic tomarrow.

Anyone know what this is? It isn't connected at all.

 

[toomany]

That looks to be the smog pump hanging out under the alternator. Not sure on what you have for emissions out there, but you can pull it off and cap the lines if you don't have to pass any checks.

 

[diesel4me]

No belt on the air pump,so its "disabled" already anyway...

Sometimes disabling all the emission crap makes an engine run worse instead of better--the fuel air mixture and cam profile are designed to work with them...as long as the vacuum hoses are not cracked and leaking and the things they operate still work,I'd just leave it be...someday you may need to pass a "visual" test and regret having removed all the emission stuff..

Out of all the devices,the EGR valve and air pump are the two that detract from performance the most..the EGR valve can be left on and its hose plugged with a ball bearing,and the belt off the air pump will keep it from doing any after-burning ...

 

[CGT80]

I wouldn't mess with taking anything off. The other guys are right. That smog stuff won't keep you from making power. The POS small and inefficient engine will keep the power low. Mine is now a 406 gen I sbc and it has all that smog stuff on it, along with ported aluminum heads, full roller valvetrain, headers, etc., etc. It hauls butt and it can pass California Smog. The smog approved parts with EO numbers are expensive, so I could see if you wanted to do headers and not stay smog legal.

The air pump adds air to the exhaust so that the cat works better. There are two check valves that prevent the exhaust from backing up into the pump.

The air cleaner diaphragm only closes off the air cleaner to cold air when the engine is cold. Same goes for the heat riser valve on the exhaust, if you have one.

Charcoal fuel canisters adsorb vapor and then let the carb/tbi suck it back up. The engine is tuned to run with these in place.

There isn't much reason to remove the cruise control, especially if it works. Mine didn't work and I don't use it on vehicles that have it......usually.

The egr can help prevent detonation, but it could also cause accelerated wear, possibly in the cylinders near it. The ball bearing trick is good, or just cap the vacuum line to it. It is better to tune the engine to not need the egr to help with detonation, assuming the engine is built properly for the application.

If you are making a show truck or the parts are bad, then I could see pulling them.

I have an 88 K5 with a new stock gm tbi engine. It is kind of slow and falls on it's face by 4,000 rpm. It gets 10 mpg. My 79 C20 has the 406 and it pulls hard to 6,000 rpm and has far more torque at 2,000 rpm than the 350tbi ever makes. It is all about making the internals of the engine efficient and then making sure the parts on the outside get enough fuel and air in and out of the engine. The new 350 stock engine (long block) was $2k. I have around $8k into the 406 without the headers, but including carb, dizzy, water pump, alternator, wires, and plugs.

If I didn't have to deal with the smog, some parts would have cost less and I would have gone more aggressive on the engine, probably even supercharged, or just with a big block.

Edit: The 406 in the pickup gets 10 mpg on the freeway, just like the K5, and it is carbed and rated for twice the torque or better. The pickup also has a .78 overdrive vs. the .70 overdrive on the K5.

 

[paratrooper307]

If you do remove the smog equipment, make sure you keep it. If you do need to revert back to it later, you don't want to have to buy back all the parts, since it can get costly and some can be difficult to source.

 

[dyeager535]

305 should have the ESC setup (knock retard) among a lot of other things, and it's just best to leave it all alone. Removing EGR without messing with the carb causes a part throttle lean surge, removing knock function means replacing the distributor and with bad heads/high compression could lead to engine issues, etc. AIR really doesn't present a problem (especially since the belt is gone) to remove unless the converter is tied into it. Probably all sorts of thermal vacuum switches and what not tied into the choke and TCC. The emissions/hose routing really sucks that vintage, which is why TBI is such a smart swap, it cleans up the engine bay immensely.

Cruise I'm not sure why anyone would want to remove. That late its completely separate from everything else, and if it fails won't harm anything. Its damn nice to have, and if you don't pull all the other clutter underhood, it's addition (one vacuum line) isn't much at all.