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Is my carb worth keeping?

Discussion in 'The Garage' started by kj1963falcon, Mar 17, 2006.

  1. kj1963falcon

    kj1963falcon Registered Member

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    Hi

    I have a 75 truck with a big block and a Holley 4118. The only info that I can find on the web says that this is a 730cfm carb.
    I am a having problem at anything past half throttle. The truck starts up and runs fine, and as long as I keep it under half throttle or about 2500 rpm it is smooth and quiet. When I go past 1/2 you can hear a loud sucking noise and if it is cold or going up a hill it will backfire through the carb.

    I have been using the search tool and reading about people who had the same problem on the board. I checked the compression and the firing order and they both look good. The plugs were fouled so I went and got some new ones that I will install tomorrow. The PO installed a HEI and I checked and it is getting over 12 volts at startup and when running.

    I think that I may have found part of the problem I found a kinked fuel line right by the fuel pump that I am going to replace tomorrow but I am worried if I have already caused damage to the carb with the backfires.

    Is this carb worth rebuilding or should I just look into getting a new one and see if it solves my problem:confused:

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  2. 1-ton

    1-ton 1/2 ton status Premium Member

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    Sure,why not. Holleys pretty much live forever, as long as you keep rebuilding them. I would replace the power valve. Those have always been the week link on a Holley.
     
  3. ryoken

    ryoken Puppy Fabricator Premium Member GMOTM Winner

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    most carbs are worth rebuilding.. corrosion, warped bases and some other circumstances will make it not worthwhile.. but usually its just cleaning, replacing a few key items and making the proper adjustments...

    holleys are notorious for blowing power valves when they backfire...

    maybe hunt your yellow pages for a local carb shop or pull it and learn yourself.. not very difficult, its just paying attention to detail... and floats and kits are cheap...
     
  4. kj1963falcon

    kj1963falcon Registered Member

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    Thanks for the ideas.
    Maybe I will try to find a book or website that tells how to rebuild a carb and give it a try. I guess the worst thing could happen is it still won't run correctly , at which time I could take it in somewhere.

    Would a power valve cause the loss of power and symptoms that I am seeing?
     
  5. 1-ton

    1-ton 1/2 ton status Premium Member

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    Yes. That is why we sugested it, but other things can cause the problem as well. like vacuum leak, ignition problem.
     
  6. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    I had a 600 Holley on my jimmy a few years back and found it was mostly a big PITA to keep in tune. i was always fiddling with it, and off road it wasn't much to brag about. I replaced it with a 600 cfm edelbrock...and it was a lot better as far as staying in tune. The Holley did make noticably more power in the upper range though. The edlebrock also sucked off road...

    I think Holley's are great carb's for a car, but if I had to have a carb again I'd use a good Q-jet.

    Rene
     
  7. 468k5

    468k5 1/2 ton status

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    no it's a POS! box it up and send it to me :D
     
  8. 1-ton

    1-ton 1/2 ton status Premium Member

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    You are right about that. Holleys are very tempermental to the slightest weather change. They are great for racing because of how adjustable they are, but are not good carburetors for every day use, unless we are talking about the Holley Truck Avenger series carburetor.
     
  9. kj1963falcon

    kj1963falcon Registered Member

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    Thanks guys!

    I am new to Holleys and I didn't know they could be picky. I am not looking for major power or anything with this truck, I just want something that is reliable and runs well.
    It seems like everyone here recommends the edelbrock Q-jet so I might start looking online to just get one of those. The last thing that I want to happen is to get way up in the mountains snowmobiling at 5000 plus feet and have the Holley decide that it wants to run like crap on me.

    Is there any vendor that eveyone recommends to purchase a Q-jet from?
     
  10. 78Suburban

    78Suburban 1/2 ton status

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    sounds alot like me

    runs terrible over 1/2 throttle, fouls plugs, backfires through the carb.........sheees, sounds EXACTLY like my 350. Which I have tried 2 distributors, a quadrajet, and edelbrock, new plug wires, new plugs, and numerous timing settings on... You may have a demon possesed motor like mine :eek1:
    thanks,
    James
     
  11. 1-ton

    1-ton 1/2 ton status Premium Member

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    Too bad there isn't someone from this board, who lives close to you, and could come over and get your engine running for you. I bet it is something basic.
     
  12. kj1963falcon

    kj1963falcon Registered Member

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    78suburban I hope that you are able to figure out what your problem is. I am hoping that my truck doesn't turn out to be a pain in the butt.:(

    I am already starting to really enjoy all of the crappy wiring that the previous owner did:rolleyes:.
     
  13. 78Suburban

    78Suburban 1/2 ton status

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    X infinity :bow:
     

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