85 305 in a k1500 - wont idle after smog removal

[SirRobyn0]

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.

Oh ok thanks, I was in the back of my head thinking that's what that was but wanted to ask to be sure. Ok the electrical tape is fine then I just wanted to make sure the connection wasn't smashed I've see that happen.

Hit it with carb clean see if you can find a leak. Check the PCV make sure it isn't stuck open. Shoot a video if you can and the best of luck to ya! We'll get this figured out one way or another!

 

[peats]

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.

Just saying simplicity is where I'm at. "72k5, '81c10 and '83 k10 diesel.I simply won't buy something with all of that aged plumbing and emission BS

 

[SirRobyn0]

Just saying simplicity is where I'm at. "72k5, '81c10 and '83 k10 diesel.I simply won't buy something with all of that aged plumbing and emission BS

Ok, I don't disagree simplicity is great, I just don't understand how your comments help him fix his truck.

As an emissions era 305 owner myself when my 305 is done, I'll likely install some flavor of 350, or maybe even a 383, but I'm not going to throw away a perfectly good 305 just because it has some extra stuff to deal with. So should we just tell this this guy to install a 350, that'll fix it? That's about as helpful as suggesting an LS swap.

And just to throw this one at you I wouldn't buy 83 diesel because I have a pretty dim view of those. But if you asked a question about it in this forum I wouldn't come into just to tell you I think it's crappy engine and how mine is better. Not nice.

Can we call this side conversation done now. Thanks.

 

[peats]

'83 k5 short fleet with 67k was a small airport truck in jamestown NY. rebuilt trans, new tires, good brakes, shocks,exhaust and suspension and a Meyer power angle plow in working condition for $5k. used it all winter with no repairs or problems. I doubled my money regardless of your dim view. did i mention no rust. i'm not sure the original poster can't do what he wants to do. there is no computer on that truck. change the carb and a few other items . 305 or 350 it's still a sbc. that's the route i would take.

 

[SirRobyn0]

'83 k5 short fleet with 67k was a small airport truck in jamestown NY. rebuilt trans, new tires, good brakes, shocks,exhaust and suspension and a Meyer power angle plow in working condition for $5k. used it all winter with no repairs or problems. I doubled my money regardless of your dim view. did i mention no rust. i'm not sure the original poster can't do what he wants to do. there is no computer on that truck. change the carb and a few other items . 305 or 350 it's still a sbc. that's the route i would take.

YES there is a computer on that truck!!!! It's got a unit that controls the timing retard on the distributor and the mixture solenoid in the carburetor. Not all the smogged 305's had Computer command carbs, but this one does, and they all had ESC module which actively retards timing when ping is detected. To be clear this only applies to 80's smogged 305's not the 70's version. We are getting way off topic and that sucks in this case but I'm trying to help educate you a little bit now because it's clear you don't understand the differences between the 305 and 350 smoggers, and that's fine.

I'm not going to argue. If you have read the thread then you'd know stripping a smog era 305 will result in issues mainly pinging. Compensating for those issues will result in a lack of power and fuel economy. I have both personal and professional experience with the smogged 305's and while I'd hardly say I know everything I do know that striping them does not typically yield results the owner is happy with, unlike the 350. Yes they are both SBC, and back in the 70's were very similar but head changes to the 305 in 80' changed all that. Sure you wanna swap heads? as part of your desmogging.

Anything more and I think we should either take it to PM or start a new thread so the OP isn't bombarded by our side conversation.

 

[fast 99]

Agree with the previous post completely. It might be too late to help with this problem as the damage has already been done. A person really needs to understand the systems being modified. I know getting rid of emissions and replacing quadrajets is king here. It isn't always a good idea.

Let a sleeping dog lie.

 

[bbgbouncer]

A couple of videos.
1. Cold start. actually ran well for 1m 30 secs. (very surprising)

xc_hide_links_from_guests_guests_error_hide_media

2. Typical run. Starts fine. dies if the throttle not used.

xc_hide_links_from_guests_guests_error_hide_media

3. Starts fine. dies if the throttle not used.

xc_hide_links_from_guests_guests_error_hide_media

 

[Bextreme04]

Have you set timing? I would also suggest you screw in the idle mix screws until they lightly bottom out and then screw them out 1-1/2 to 2 turns each. You should NOT need to pump the gas at all to get it to start. It should be a single pump to the floor and then slowly release to set the choke and high idle cam.

It sounds and runs like you have a major vacuum leak. With that big of a leak you should be able to hear it sucking through the spot that is leaking.

 

[fast 99]

Really sounds like it's misfiring. Could be a vacuum leak, stuck EGR, or ignition? Haven't followed this thread from the start, have you gone back and double checked everything?

 

[Bextreme04]

I agree with the misfire also, which is why I was asking about timing and mixture.

What do the plugs look like? I'd pull at least one plug and see what it looks like.

 

[Strick]

I'll agree with some of these other folks. Ditch the worn Q-Jet and distributor. Install a new square bore intake manifold and carb along with a new OE style distributor from Accel or MSD. You won't have to worry about spark control modules, throttle position sensors or mixture control solenoids as well as the ECM when doing this. I just did a conversion on an '86 MCSS that had similar issues. When I put on the new parts it ran like a gem and the back tires magically smoked...
305 GM engines have caught a bunch of crap over the years. I've had a few and have had good service from them. IMO where GM failed was trying to "inject" a carburetor. All this ancillary junk was added to the fuel and ignition system on an engine that was initially developed in the mid 50's. I have done several swaps over the years in where I replaced the distributor with an old style 4-Pin module with vacuum advance and took the ECM Q-Jets and used them for target practice. I'd use an older style Q-Jet or perhaps a square bore Holley or Weber instead also.
I'd definitely plug the vacuum advance into a ported vacuum on the front of the Q-Jet you have now. This may help your idle situation immediately. Good luck and happy wrenching.

Strickland

 

[SirRobyn0]

Well I'm with @Bextreme04 and @fast 99 Sounds like possible vacuum leak, possible misfire. I'm think I'm in the large vacuum leak causing the misfire. When I'm in an environment where I can watch them more closely I'll try to see if I can see anything, but I don't think it would be one of the little vacuum lines I'm thinking like the brake booster or large plug off the carburetor. Working at home I'm sure you don't have one, but a smoke machine would make short work of location that leak.

 

[fast 99]

Try this, plug or remove every vacuum line, if it still runs poor/same then they are eliminated. That will narrow it down somewhat. If it runs ok, reconnect them 1 by 1 until the offender is located. I just did that on a current project. Found a bad charcoal cannister.

 

[SirRobyn0]

Try this, plug or remove every vacuum line, if it still runs poor/same then they are eliminated. That will narrow it down somewhat. If it runs ok, reconnect them 1 by 1 until the offender is located. I just did that on a current project. Found a bad charcoal cannister.

Yes, and that is a very good idea and the canister is often over looked as a possible vac leak source.

 

[RecklessWOT]

Yes, and that is a very good idea and the canister is often over looked as a possible vac leak source.

lol one more reason to get rid of that god awful thing