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Which Carb will work?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by woodpecker, Mar 4, 2001.

  1. woodpecker

    woodpecker Registered Member

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    Okay,

    I've been blessed with the last year of stone-age technology (1986). No ECM, no "brain," no nothing EXCEPT little solenoids in the carb that control themselves (or so it's been roughly explained).

    I'm having enough minor carb problems that I'm conisdering replacing the carb. Problem is everyone trys to sell me a $500 carb with solenoids, etc. If my rig has no ECM, couldn't I put an old-fashioned carb with no electronics (except the choke) on it in place of the stock Q-Jet? There's no brain to link the carb and EPA stuff like the EGR (which is currently plugged off due to failure).

    Do I HAVE to put another super-expensive electronic carb in?

    Thanks for any input!
     
  2. gokartergo

    gokartergo 3/4 ton status Staff Member Moderator

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    Yes, I am in the same boat has you. Yes it is still computer controlled. I have rebuilt the card. And then had it professionaly done. And I still can't get it right. The only explaination I have left is it has a crack in it in the inside. The guy before me blew the heads off of the motor. So he drove it hot a lot. I put in a new crate motor. But can't get the carb to work right.

    Beccome one with nature..............Then marinate it...
     
  3. prjt_blzr

    prjt_blzr 1/2 ton status

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    You've been blessed all right just not in the right way. 1986 was the "pinnacle" of carb technology. The emmisions became so difficult to meet with a carb that the MFGs found it less expensive to run fuel injection after that year. If you do not have emissions in your area you could run a non-emmisions Q-jet on your motor. You will need to do a lot of tuning as the motor is currently set up to run with all the gee wiz stuff on it. If you have emmisions in your area you are stuck with that carb or converting to TBI. I've messed with these carbs before and they have a tendancy to crack internally and messing with the idle and low speed performance. If I were to do this again I would pursue the TBI option if 1987 had a similar application. It will be a lot of work but TBI is much more reliable than these POS carbs.
     
  4. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    79-80 Carb should work and suport all your emmisions crud to keep tha Nazi's happy and other than not haveing the mix solinoide it looks identical and will convert to electric choke.

    Diging it in the dirt with my K5's
    Grim-Reaper
    <A target="_blank" HREF=http://grimsk5s.coloradok5.com/>http://grimsk5s.coloradok5.com/</A>
     
  5. dyeager535

    dyeager535 1 ton status Premium Member

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    You'll be missing the TPS if you go to an older carb, which is necessary for the lockup, assuming you have an automatic tranny. You will also have to replace the distributor at the same time if you go to an older carb. There are ways to adjust/fix the TPS and MC solenoid, I can't think of any sites offhand that actually tell the correct dwell and such though, sorry.

    Dorian
    My K5 and Chev/Olds tech/links page: <A target="_blank" HREF=http://www.dorianyeager.com/index2.html>http://www.dorianyeager.com/index2.html</A>
     
  6. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    As far as I know the 86 only got the mix control solonoid in the 48 state version. The solonoid was controlled by a temp sensor in the water neck. Once it reached operating temp it leaned it out. The TPS model is the CCC (computer controled carb that did have an ECU,TPS and O2). This was used a lot on cars but I have as yet to see it on a truck. Maybe the 85-86 California emmision trucks had it but I have seen plenty of 86's without it. In 86 the tranny had a sort of TPS but it was a cable simular to a kickdown cable off an older tranny. It will operate fine on a standard carb. The only thing I'm not sure of is the lock up converter. I think that was vacum controled and still work with a regular carb. I think that carried through 91 on the old body trucks. it may have been different for the new body pickups that came out in 88. In 87 they went to true FI

    Diging it in the dirt with my K5's
    Grim-Reaper
    <A target="_blank" HREF=http://grimsk5s.coloradok5.com/>http://grimsk5s.coloradok5.com/</A>
     
  7. dyeager535

    dyeager535 1 ton status Premium Member

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    Actually its the other way around. (or should be, since I don't have absolute proof) Easy enough to prove though. Drivers side plug on the carb is tps. Passenger side plug is MC solenoid. Cars for export (Caprice, Monte Carlos, the like) with 4 spd OD transmissions (automatic of course) received ONLY the TPS. Since MC solenoid is handled by the ECM, and was to try and help with emissions (secondaries never did go computerized) it was not needed for cars that were going to countries that did not have emissions. TPS didn't/doesn't need the ECM to function in those cases, since it was SOLELY for unlock/lock functions, and could also be tied into the cruise control, which was also seperate of the ECM.

    Since trucks didn't have to meet car emissions standards in the US, GM stayed away from the MC solenoid in trucks as long as possible, as well as the TPS. Now I can't comment on '86 authoritatively, since I haven't owned one. I can on 1983 and 1984...neither has the MC solenoid nor the TPS. I would be surprised if in two years, they went from neither, to both, thus adding an ECM to the truck.

    The TV cable is what you are thinking of, and is a primitive kick down/shift firmness controller, that was handled electrically after our trucks met their demise in '9. That tranny is the 4L60E.

    Torque converter may or may not be tied in with the TPS on th etrucks, although it would make little sense not too, since the the cars had used TPS for lockup since '81 Federally.
    Temp sensor, among other things, like cannister purge probably, delayed tranny lockup until the engine met X temperature, to warm up the vehicle faster.

    Dorian
    My K5 and Chev/Olds tech/links page: <A target="_blank" HREF=http://www.dorianyeager.com/index2.html>http://www.dorianyeager.com/index2.html</A>
     

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