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1985 K5 OEM Carburetor

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Old 07-11-2011, 01:09 PM
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Default 1985 K5 OEM Carburetor

My 1985 K5 won't pass smog because the carb is running to rich. Taking a closer look at the carb with a friend that is a mechanic. We noticed that not all of the electrical lines are hooked up to the carb. There are a few lines that don't seem to fit to any thing on the carb. So I would guess this is not an OEM carb on this K5.

The carb that is on it is a Holley Quadrajet 4 barrel w/ electric choke. My mechanic friend pointed out that the green plastic electric connector on top of the front of the carb controls the amount of fuel and was not hooked up, and none of the connectors hangout without a place to go seemed to fit.

So does anyone know the OEM part numbers for the carb that should be on this K5.

Engine is 350.

Or if anyone has some detailed pics of the carb and the wiring harness i can compare to mine to see what is missing or whats different.

Any help would be great. I love this truck and won't to get it back on the road/dirt. Thank you.
 
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Old 07-11-2011, 02:32 PM
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Could you take a picture of what you have & the connectors in question and post them here?

You likely should have the E4Mx carb which was a feedback type of carb with some electrical components to supposedly lower emissions. What really ended up happening with them is that the mixture solenoid would fail open causing a rich condition. Many people just tossed them in the garbage and replaced them with a full manual Q-jet to do away with all of the electrical nannies.
 
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Old 07-11-2011, 02:49 PM
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Thank you for the reply. I take pics tonight. What model of manual holley would fit. That sounds like the way to go. Does the E4Mx get better mpg than the manual?
 
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Old 07-11-2011, 02:53 PM
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You need a Quadrajet. Regardless of who made it (Holley, Carter, or Rochester), all Quadrajets will bolt up to your intake. Some may have different throttle/kick-down brackets, but in terms of how they attach to the intake, they all are the same.

If all you failed on is the emissions, I would adjust the carb to lean it out and see what it tests at. This can be accomplished primarily by turning the idle mixture adjustment screws clock wise. They are located on the very front of the throttle plate (lowest plate on the carb), one on each side.

If you failed as a result of having a manual carb where an electronic carb was originally, then you have to go back to the original carb.

As far as which works better... When the E4Mx (x is a variable here whether that be E, C, or ED for the actual carb designations) was working, it was a fairly efficient carb. But when not working, they were a nightmare. The manual carbs are much easier to get adjusted properly and keep adjusted properly, but may take periodic maintenance.
 
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Old 07-11-2011, 03:07 PM
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Thanks again. swartlkk you are a wealth of knowledge. I will check with the DMV on if I can get by with a manual carb. Have a great day.
 
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Old 07-11-2011, 03:10 PM
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I wouldn't bring it up unless specifically brought to your attention at the time of inspection. If all they are doing is reading tailpipe emissions and you have the proper catalytic converter installed & functioning, manually lean out the mixture and see if you can get it to pass.
 
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Old 07-12-2011, 12:06 PM
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The port circled in red is not connected and I there isn't any connector that fits it.
 
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Old 07-12-2011, 12:15 PM
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Is that your carb? If so, that is one of the E4Mx carbs. If you do not have a connector for the mixture control solenoid, it will default to a rich mixture. I'd toss a regular mechanical Q-jet on there, tune it up and then go in and see how you make out. Is there a connection to everything else on the carb?
 
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Old 07-12-2011, 12:41 PM
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No this isn't my carb, but i found this pic that was better then the one i took. This is the same carb that is in mine. I grabbed the numbers off of it (17083204). My wiring does hook up to a Tall oval connector on the front-right of the carb. I was searching the net and found this number 17085238 as a model that should be OEM on an 85'. Does that sound right? I think as you suggested putting on a manual carb would be best. Do you know the model number of a manual carb that would work for me?
 
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Old 07-12-2011, 12:53 PM
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It is very likely that your original carb had a different mixture solenoid than the one pictured, but did have the idle solenoid and electric choke. If I remember my q-jet models correctly, I believe that would make it the M4ME Q-jet. What was on your truck wouldn't call out a second to last number of 3 though as that was reserved for Cadillac specific carbs. 0,1, or 2 were Chevrolet. So your truck would have likely had a 170852x8 (where x is 0, 1, or 2) and would be an M4MED or M4ME carb.

Do you have a connector that looks like it might go to the mixture solenoid, but just doesn't fit? How many connectors are there & where do they reach on the carb?
 

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