85 305 in a k1500 - wont idle after smog removal

[SirRobyn0]

The emissions equipment being different for C/K10 and C/K20 is absolutely correct. It is also different within C/K20 based on GVWR. My 80 K20 did not come with cats or EGR because it is an 8600GVWR option, which pushed it into "heavy duty emissions" compared to a standard C/K20 that was below that rating and therefore fell into light duty emissions. California emissions are also different and have their own break points and differences.

That's right and for me my 84' C20 has a cat, air pump and of course an EGR valve, but does not have a feedback carb.

 

[bbgbouncer]

Thanks all for the responses. im a simple man. air, fuel, spark. all you need right? hehe. ok here are some picks of what I removed. the Dist Adv was originally hookup up to a vacuum that is temp controlled. it now goes to a vacuum directly on the manifold.

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[bbgbouncer]

more pics

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[SirRobyn0]

Thanks all for the responses. im a simple man. air, fuel, spark. all you need right? hehe. ok here are some picks of what I removed. the Dist Adv was originally hookup up to a vacuum that is temp controlled. it now goes to a vacuum directly on the manifold.

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Oh boy. It is kind of ok to move the dist to manifold vacuum, depending on who you ask.

The picture 4th one down that says "disconnected EGR valve passengerside exhaust. That is not the EGR valve that is the EFE valve, it takes the place of the heat riser you need to hook it back up properly or you may have problems with the way the engine runs, not when it is stone cold, and not fully warmed up but in between full cold and full hot.

You need to hook the canister back up. Without that you'll be sucking in unfiltered air into you fuel tanks and pushing vapor out under the hood.

This actually makes me a little bit angry. IDK what you were thinking just tearing that stuff off, but I'm glad you have the pieces.

Get the EFE, the canister hooked back up. Then put the distributor back the way it was. The ESC system needs the distributor hooked to ported. Once you have it running right again you can play with the distributor on manifold vacuum, but I don't think the ESC system will really like it.

I hope you have read though all the post here and now realize you can't treat a 305 like a smogged 350. Good luck let us know what you do and what happens.

 

[bbgbouncer]

thanks @SirRobyn0 i will work on hooking this all back up on the weekend.

 

[Bextreme04]

Very interesting. I didn't know there was that much variability in these trucks for the same engine size in the same production year, but now I do!


Nor was I aware of the differences among 305s... Makes me wish I still had the 305 from my Monte Carlo. I don't remember seeing dished pistons in that engine when it was apart, but my '85 305 definitely has low compression dished pistons in it.

That satisfies my learning for the day. Hopefully the OP will learn something in this thread too!

Another terrible difference between 70's and 80's engines in general is that even if the cylinder heads have the same casting number, the production was moved or castings changed without a different casting number. Some of them moved to mexico, some of them just got new castings with the same number, but 70's heads(in general) will have thicker castings that have more meat to port and 80's heads will be thinner and more prone to cracking. Sometimes the casting is also noticeably rougher.

I had a 1971 4 bolt main 350 from an A-body that I used as a donor for my truck last year. When I got it apart, it had dished pistons that were .038" down in the hole. With 76cc heads, that gave it a stupid 7.8:1 static compression ratio and a huge .085" quench with stock head gaskets. That's with a completely untouched stock 350!!! I can't imagine how bad some of these 305's must be.

 

[SirRobyn0]

thanks @SirRobyn0 i will work on hooking this all back up on the weekend.

I'm sorry if I seemed overly harsh in my last post in re-reading it I don't think I should have been. Yes you really should get the canister and EFE hooked back up. The EFE does need to go though the temp sensor so it opens and closes with engine temp. The distributor like I said you can play with hooking it to ported or manifold vacuum. While I'm a big believer that it should go though the factory check valves, if you have them in all reality it does not. You can connect it directly to a ported or "timed" vacuum source, and play with hooking it to manifold once you have the truck running properly again so you can see if you do or don't like the effect. Other than cleaning up some vacuum lines there really isn't a good reason to run without the canister, but if you really do want to go without it, at least get it set up to vent under the bed and / or filter it so it at least has that.

I'm really not trying to be preachy I just want you to make choices that will be good for the truck longer term. If you want to eliminate some of that stuff you'd be far better to do it one thing at a time so you can see the effects as you go.

 

[bbgbouncer]

i have hooked up most of the items. I dont have the air pump or decel valve connected (cant find them)

Still having the idle issue. I have backed off the choke idle screw and the idle screw. I had turned them in before. I have adjusted the idle screw one turn at a time. still wont idle. I will keep adjusting incase Im not being patience enough.

here is the Vacuum diagram from under the hood. the two items circled are the ones that were not connected. lines are either capped or eliminated that would go to them.

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[85K304SPD]

Maybe your throttle shaft holes are worn and need bushed. That is a pretty common problem. It sounds like something in the carburetor is keeping it from idling correctly.

 

[SirRobyn0]

i have hooked up most of the items. I dont have the air pump or decel valve connected (cant find them)

Still having the idle issue. I have backed off the choke idle screw and the idle screw. I had turned them in before. I have adjusted the idle screw one turn at a time. still wont idle. I will keep adjusting incase Im not being patience enough.

here is the Vacuum diagram from under the hood. the two items circled are the ones that were not connected. lines are either capped or eliminated that would go to them.

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Ok, so of course this could be a coincidental failure. For the moment don't worry about the air pump, that won't cause your idle issue. The decel valve is on the carburetor front side in front of the linkage. Make sure that is hooked up.

Check for any other vacuum leaks. Can you run the engine long enough to spray carburetor cleaner around the vacuum connections, carb base and intake to see if there are any vacuum leaks. I'll think a little on this and see if I can come up with more ideas.

 

[bbgbouncer]

@SirRobyn0 I dont see that decel valve. there is a valve on the backside of the carb by the dist. it is hooked up to a vacuum on the back of the carb. this was never disconnected. I added some pics of what the current state looks like. Still need to check for leaks.

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[peats]

All of this info makes my head hurt. My '81 350 has a vac line to the dizzy and a pcv line to the valve cover with a quadrajet. Been running flawlessly since i put it together 3 years ago. no power brakes and no choke. bare bones

 

[SirRobyn0]

If it had one it would be where I circled red.

To me it does not look like it ever had one or if it did it was a long time ago. So if I were you I'd toss it off the list of concerns.

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Where I circled in yellow, that is the mixture control solenoid. So this is a computer command controlled Feedback carburetor or CCC for short. You should probably take the electrical tape off and see why it is all taped up.

That carb in general looks well warn, but that doesn't mean it's bad.

Some questions:
Do you have access to a vacuum gauge?
Can you get it running and spray some brake clean or carb clean at the carb base and vacuum lines to see if there are leaks?
Are you able to shoot a video of running?

The only other thing I can see in the photos that I'm a little concerned about is this, in the below picture circled in yellow is the component. I'm sorry not being there looking at it in person I'm not 100% sure of what it is, but the end I circled in red looks almost like it should be attached to something. That wouldn't happen to be a large vacuum leak?

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[SirRobyn0]

All of this info makes my head hurt. My '81 350 has a vac line to the dizzy and a pcv line to the valve cover with a quadrajet. Been running flawlessly since i put it together 3 years ago. no power brakes and no choke. bare bones

IDK, what am I suppose to say to this? What's your point? A emissions era 305 is a different animal than a 350 and cannot be run with a simplified system like that.... It is what it is.

 

[bbgbouncer]

So electrical tape. I have looked at this. the plug has the locking tab broken. so I guess he taped it. it is due for new tape or a fix.
second yellow is the temp sensor that goes in the air filter housing. It is sitting there so that I can have all the hoses connected and air filter housing out of the way.

no vacuum pump but I will spray connections with carb cleaner once I get a second pair of hands to help. I will take a video and post that.