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Which New Carb Is Best/Easiest Replacement On A 1986 GMC 350 "M" Series Engine??

Discussion in 'The Garage' started by Dave1, May 2, 2005.

  1. Dave1

    Dave1 Registered Member

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    My old stock 4brl carb on my 1986 GMC 3/4 Ton 4WD pick up truck 350 "M" series engine appears to be leaking thru the bottom plugs causing very rich running condition at idle and low speeds. The butterfly shaft is sloppy and this carb has over 200K miles on it. I am thinking/wondering if I would be better off buying a new replacement carb than rebuilding this one.

    I have heard that a new carb can be bought for not much more money than a complete carb overhaul would cost.

    Any opinions for which is the best option?

    If new carb is suggested, which one would be a good bolt on replacement that would not require any mods or extensive tuning work to get it right?

    Thanks, Dave
    davisalf@aol.com
     
  2. dyeager535

    dyeager535 1 ton status Premium Member

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    IIRC, you can pull the carb and seal those plugs up without disassembling the carb. Just need a new base gasket. Been awhile since I had a Q-jet in my hands though.

    It's possible that's causing your problem, but in my experience it's not likely. For the cost of a base gasket and JB Weld, it would be pretty cheap to make sure. Those plugs ARE an issue, so you wouldn't be wasting time doing it, even if it doesn't fix your problem.

    Bushing primary throttle shaft is $40 around here at a carb shop, rebuild kit is about $20, new float maybe $10, lot cheaper than buying a "new" carb.
     
  3. Dave1

    Dave1 Registered Member

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    I am not a carb person so I would likely hand it off to a overhaul person or shop. I was told the cost would be $150-$200 for an overhaul. Don't know for sure but have been told I can buy buy a brand new replacement carb from Edelbrock for about $250. Seems like it may be wise to spend a little more money and get a brand new carb.

    I was hoping if I did go for the new carb that it would be a bolt on deal and not require any tuning, jetting changes, linkage changes, etc.

    Opinions???

    Dave
     
  4. PhoenixZorn

    PhoenixZorn 1/2 ton status

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    You can rebuild a Q-Jet for about $40.00 if you find the rebuild kit and do it yourself... Yeah, having someone else do it, you might as well buy a new carb... Holley's are easy to tune without taking the whole thing apart, and Edelbrokes are the opposite... you need to take it down to pretty much do anything tuning wise, but once tuned, they are great.

    On a side note, I have a Holley 600 sitting in the for sale forum of this site... check it out.
     
  5. Dave1

    Dave1 Registered Member

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    Are the new Holley carbs an easy bolt on application where linkage and everything hooks up just like on the stock carb?

    My rebuilt 350 "M" series engine is stock with no mods. What tuning would be required with a new Holley carb?

    How does the cost of a new Holley carb for my engine compare to the cost of an Edlebrock carb?

    Thanks, Dave
    davisalf@aol.com
     
  6. PhoenixZorn

    PhoenixZorn 1/2 ton status

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    The holley will be cheaper by far... for a stock engine, even a Holley 600 is "too much" carb, and you would want to go with a 550 or so... the Qjet is your best bet because it was designed to run on your engine as it sits right now. The Holley is very much a "bolt-on" product, needing about 15 minutes of work plus fine tuning for idle once you hook it all up. I will note however that the Holley fuel supply line (Filter hookup) is on the opposite side of a QJet, and you will have to reroute your fuel line.

    I know nothing about Edelbrocks other than they are expensive and hard to tune...

    On a side note, no matter what people tell you, you DON'T need a double pumper.
     
  7. beater_k20

    beater_k20 Banned

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    for a NEW carb... Edelbrock 1904 hands down. problem is finding someone who still has one in stock, as Edelbrock recently discontinued them.
     

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