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so many question marks with my 81

Kaiser85

Kaiser85

1/2 ton status
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Mar 23, 2013
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Location
Tyler, Texas
Ok so i bought a nice 81. It originally came with the 305, but now has a rebuilt 350. Or at least thats what the PO claims... but ive already caught one lie.

Anyways..... this kinda idles like ****. Gotta jazz it up pretty good after a cold start. After that, it seems okay, but still not as smooth as i know it can be. It has a carter quad jet carb. I am very familiar with the principles of a carb. But mainly on dirtbikes. Ive rebuilt and tuned lots of keihin PWKs, FCRs, and CVKs..... this though, is foreign to me. It seems like on the pass side of the carb resides the choke. Looks to be an electronic choke with a single blade style connection.... problem is... theres no wires plugged into it. There IS a loose wire nearby thats got a broken connector, but it doesnt look to be the one that originally hooked up there.

Also, theres a rubber hose coming off the front of the carb with a bokt stuck in the end of.it. im kibda thinking it was originally meant to plug into the bottom of the air cleaner.... thoughts???

Choke???? Wire that was sitting atop the manifold right under it
0330131712_zpsb95ed796.jpg


Choke??
0330131711b_zpsee91a78f.jpg


This piece has no tension on it either way, and appears to do nothing... the other piece below it manipulates the flap over the primary, which is open 100% of the time, always... running, not running
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Like this
0330131711_zpsd9301567.jpg


Heres the hose with the bolt... classy. It attaches to the carb below my hand in the pic
0330131713_zps2065e301.jpg


Then theres this plugged up hose.... you can also see what i believe to be the choke, and the mystery wire on the left
0330131713a_zpse9bfa207.jpg
 
Thats a Quadrajet carb,not a Carter AFB...the choke is electric,and is not hooked up,without the wire hooked up to a keyed 12V source,it will never let the choke fully open,and it will foul plugs and flood,and thats why it idles lousy probably...the plugged off hose might be for a PCV valve,which is a must to have hooked up and working right,the smaller hose plugged off probably used to go to the thermostatic air cleaner "door" ...or maybe the choke pull off,which also must work to let it idle after a cold start without over-choking ...
 
Whoa..... "theres your probem right there...."

Thanks man. Ill get on all this.

When you say it needs a 12v keyed source, what do you mean. It needs 12v for the choke.to function? I very seriously doubt the wire that hanging there woukd actually operate anything if i plugged it up... its probably been cut or disconnected somewhere else. Let me make sure ive got this concept down-pat. For the choke to function, it need 12v of current running to it. Then, when choke is no longer needed, the 12v stops flowing to the choke, and the choke is no longer being used???? Is this correct? If so, what TELLS the 12v to STOP flowing to/operating the choke?

The large plugged up hose- what would that hook up to? An orphice in the valve covers???

The small plugged up hose- what would that connect to??
 
Under that black cover where the choke wire plugs on,is a electric heating coil with a thermostat spring that operates the choke butterfly...when its cold the spring contracts and closes the choke,when you start it,12V goes to the electric choke and begins to heat up the heating coil inside it,then the choke starts to open slowly..the thing gets 12V constantly any time the key is in the "run" position...also the choke vacuum pull off (behind the choke on your carb) opens the butterfly slightly to prevent flooding or over-choking after a cold start...

Looks to me like that bigger hose was going to the carb bowl vent,which usually goes to a vacuum charcoal canister in the fenderwell--the PCV valve looks to be hooked up,it goes to the valve in the valve cover,and should plug into the large nipple on the center of the carb up front on the base of it..the smaller hose could be for the vacuum advance on the distributor or the air cleaner door,or many other smog related switches maybe,depending on the year of the engine,etc..
 
Just my opinion, but i'd ditch the quadrajet carb...ive had them on 2 or 3 old chevys i bought, and that thing was the first to go. They can and do work, but I hate em. Just get a new holley or edelbrock and be done with it. Im sure others will chime in
 
This might help. This is non califuka auto trans 350 Blazer and single tank truck
0900c152800aef96.gif
 
Well give me a better description or a photo of the compartment. I already see one part missing on thermostat housing. I think some one hacked the de emission of it.
Does it still have original exhaust and air cleaner?
 
Its an after market air cleaner. Just a round housing atop the carb. Exhaust is long tube headers. And yes theres something missing on top the thermostat housing.

Id LIKE to not have any of the emissions stuff. I guess that is makes a nice smooth idle, but i know it can be accomplished to some extent WITHOUT that stuff. Im willing to just buy a new carb that doesnt have all the emmisions crap. If i was gonna go that route, what would yall do?
 
Ok your choke is probably unwound. loosen the three screws and rotate the center counter clock wise while holding the throttle open. once it closes the choke plate tighten the screws back. This will at least give a starting point. Check what you believe is the choke wire for power and plug it in. The broken part on the t-stat housing was a thermal vacuum switch. Since you want to remove the emissions controls you don't need it. The vacuum line with the bolt in it probably went to the factory air cleaner. My suggestion to correct the rough idle is to replace all the vacuum lines. Your carb is an emissions carb and was designed from the factory to run as lean as possible and therefore is very sensitive to vacuum leaks. Only replace the lines you need like pcv and vacuum advance, also the vacuum modulator line to the trans has rubber at both ends. last is the line into the cab to run the dash vents. Everything else you can cap off. (use vacuum caps)Then check your timing and adjust if necessary. If after all this you still have a rough idle then I would adjust/ rebuild the carb. Most Q-jet problems are from improper adjustments from backyard hacks. I have an 86 with all the emissions still on it and 11 previous owners per carfax. Anything and everything was wrong with this k5. Its taken awhile but I've finally got it dialed in. Happy Tuning!
 
The way I de emissioned a 1980 was got a plug for the themostate (or just get a chrome no hole). Cut a 1/4 metal plate for over the EGR valve. Left the electronic choke and got plugs for the other lines. If you want I will try to remember the ones and mark the diagram.
 
my .02...the choke wire as others have said is unplugged, the wire with the broken blade connector, usually has a locking tab to hold it to the spade on the choke housing.
The carb indeed could be a Carter quad....Carter did make quads as well as Rochester.
The Quad can be a great carb when it is properly tuned and is probably less maintainance than a Holley IMO. I haven't messed with Edlebrocks, but I believe they are similar in function to the Quad.
Many of the emissions hoses can be removed if given proper thought of what each device/solenoid/switch does. I had most removed from my 85 quad, drilled the jets out a couple drill sizes (like .003) and it ran great. Proper choke functioning is critical, as well as proper secondary rods etc for your particular engine.
By the way, check the block casting #, and stamped engine pad #'s to see exactly what your engine is.
 
Thatd be awesome metro. I poked aroubd a few minutes ago, abd will probably re-connect the disconnected hoses, and see what it does.

Alas, i was being hurried to the in-laws for easter
 
Been thirty years since I did it and this is from memory. I did the valve that is missing from thermostat housing. Where the blue is on fuel vapor canister is where I reversed the T and connected the outer line.
0900c152800aef96.gif
 
Take the air cleaner off before your next cold start and look at the choke blade. Then give the throttle a quick tap to see if the choke does anything. After starting the engine, watch to see if it moves and where it ends up when the engine is warm.

It should snap shut when the engine is cold and place the throttle on the "high idle stop". Then once the engine starts, the vacuum should active the pull-off to move the choke blade to "just barely open". As the engine warms the choke should open up and touching the throttle should drop the idle speed back down.

A choke that doesn't work right is misery.
 
It doesnt snap shut. Its always wfo. Always. 100% of the time. It never, under any circumstance, unless manipulated by hand, EVER is anything other than WFO....

..... EVER. :)

Heres where im at. Id assume since the PO didnt have the wire hooked up to the choke to heat the coil spring (it probably a dead wire) he just jank-rigged the choke.to be WFO alk the time. Thats my guess at least. The dude is one of those types that knows JUST ENOUGH, to fu(k $H!t up
 
Metrodps..... dude.... thank you!!

Okay ill try to be as descriptive as possible (from memory) and describe whats still in place.

The large hole with the big yellow zinc bolt crammed in the end is obvipusly disconnected. Looks like it was cut by the fan the other end.is still connected to the cannister, ontop the left fender-well. There is also a smaller black hose coming FROM the black cannister. It too is unplugged and just sitting there.

Ill report back this afternoon with some more intel.... it is my friday, im abput to make stuff happen this weekend!!!
 
Metrodps said:
Been thirty years since I did it and this is from memory. I did the valve that is missing from thermostat housing. Where the blue is on fuel vapor canister is where I reversed the T and connected the outer line.
0900c152800aef96.gif
Click to expand...
The yellow was the ones I deleted and of course the EGR was removed and blocked off by metal plate with gasket under it. Can you make sense of the diagram?
 
Yeah, so far so good. It may be easier with the mess in front of me..... where is the EGR located????

Also... the EFE TVS.. What is that, and where?
 
If it is an 81 motor it should be where #3 is at #1 should be the thermostat housing one and to the left on intake should be #2
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