Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

Scrapping TBI, looking for carb recommendations

Discussion in 'The Garage' started by Russ, Nov 29, 2006.

  1. Russ

    Russ 1/2 ton status

    Joined:
    Feb 17, 2000
    Posts:
    509
    Likes Received:
    0
    Location:
    Summerdale AL
    I have decided that I do not have the smarts or the patience to try and tune the TBI to my engine so I plan to remove it and set up a carburetor instead. Any size/brand recommendations would be appreciated. I am thinking 750 CFM but not sure?
    Engine is a .030 over stroked 454 (489) running 10:1 pistons and XM270HR cam. Edelbrock large oval port aluminum heads with roller rockers. Longtube headers with dual exhaust.
    Truck is my 88 crewcab dually that is used primarily as a farm truck with occasional towing (approx 10K).
    Thanks for any help,

    Russ
     
  2. beater_k20

    beater_k20 Banned

    Joined:
    Dec 9, 2003
    Posts:
    10,276
    Likes Received:
    0
    Location:
    Elkhart, IN
    quadrajet
     
  3. nvrenuf

    nvrenuf NONE shall pass! Premium Member

    Joined:
    Jan 7, 2002
    Posts:
    13,088
    Likes Received:
    252
    Location:
    Mobile, Al.
    I agree, I think the Q-jet is the way to go. It should get good mpg when driven reasonably. Ratzila had a Jet (Stage 2) q-jet on a fairly healthy 454 and it drove really nicely.

    That said... How you doin Russ? I hope the move to Tn went well. Look for a thread titled "crew cabs" and post a pic of yours. :wink1:
     
  4. mouse

    mouse 1/2 ton status

    Joined:
    Nov 10, 2003
    Posts:
    1,448
    Likes Received:
    0
    Location:
    Great Falls Mt
    PM me if you're interested in selling the TBI components.
     
  5. SkysTheLimit

    SkysTheLimit 1/2 ton status

    Joined:
    May 23, 2003
    Posts:
    530
    Likes Received:
    0
    Location:
    Tampa, FL
    I've got a holley 4050 on top of my 496. no choke, not very nice to drive but man will it run!
     
  6. Russ

    Russ 1/2 ton status

    Joined:
    Feb 17, 2000
    Posts:
    509
    Likes Received:
    0
    Location:
    Summerdale AL
    That Jet quadrajet is fairly expensive. I was looking at the Holley 4150's and 4160's as they are a little more reasonable. I am planning on running a vacuum secondary to keep it a little more street friendly.
    I am just hoping for something with a little less aggravation than I have had trying to make the TBI run right on this engine for the last six months.
    Mainly I was curious if the 750 would be big enough or should I be looking at an 850 carb?

    John - Tennesse is a great place to live and I am enjoying retirement. Hope all is well with you. I don't believe I can post pictures of my truck as I am not a paid member anymore.
    Thanks for the help,

    Russ
     
  7. nvrenuf

    nvrenuf NONE shall pass! Premium Member

    Joined:
    Jan 7, 2002
    Posts:
    13,088
    Likes Received:
    252
    Location:
    Mobile, Al.
    You might try contacting "Thunder" (I'll try to find his email), he seems to be really good with fuel injection and trouble shooting. :wink1:


    Oops, forgot about that - I'll fix it. :thumb:
     
  8. RingMaster4x4

    RingMaster4x4 1/2 ton status Premium Member

    Joined:
    Mar 4, 2001
    Posts:
    2,049
    Likes Received:
    0
    Location:
    Bartlett, Texas
    I have run a Holley Street Avanger 770 on the 427 in my blazer for the past 3 0r 4 years with no problem. I will use the same on my 454 I am building for my chevelle.
     
  9. SkysTheLimit

    SkysTheLimit 1/2 ton status

    Joined:
    May 23, 2003
    Posts:
    530
    Likes Received:
    0
    Location:
    Tampa, FL
    Mine's an 850 but it's a pretty stout motor and has nitrous on it. 750 I'm sure would be plenty.
     
  10. mudbog42

    mudbog42 1/2 ton status

    Joined:
    Jul 16, 2006
    Posts:
    452
    Likes Received:
    0
    Location:
    Florida for now
  11. Russ

    Russ 1/2 ton status

    Joined:
    Feb 17, 2000
    Posts:
    509
    Likes Received:
    0
    Location:
    Summerdale AL
    Thanks for the help everyone. It looks like 750 is the size to go with. Now I just need to round me up an intake and distributor and thin out my wiring harness.

    Russ
     
  12. SkysTheLimit

    SkysTheLimit 1/2 ton status

    Joined:
    May 23, 2003
    Posts:
    530
    Likes Received:
    0
    Location:
    Tampa, FL
    I don't know about 454 TBI but a 350 TBI is something like 470cfm. 454 probably a bit higher maybe in the 500 range. 650 or 750 I would think would suit you fine.

    I just pulled the harness out of my truck last weekend. It was scary at first but thanks to Beater_K20 i got it out.
     
  13. gmc4cw

    gmc4cw 1/2 ton status GMOTM Winner

    Joined:
    Jul 19, 2006
    Posts:
    3,907
    Likes Received:
    0
    Location:
    west chester, Pa
    I have had a truck avenger for a few years now. I love it. replaced my quadrajet with it. runs at crazy angles that the last carb would stall at. great right out of the box to. all I adjusted was the electric choke.
     
  14. big83chevy4x4

    big83chevy4x4 3/4 ton status

    Joined:
    Mar 22, 2002
    Posts:
    6,587
    Likes Received:
    0
    Location:
    Sheridan, Michigan
    the TBI 4.3 up to 350 had a 670 cfm throttly body, i believe the 454 had a 770 or 780. not exactly sure on that.

    im either going with a 770 truck averger or the 795 qjet on my bigblock.
     
  15. makovai

    makovai 1/2 ton status

    Joined:
    Jun 6, 2006
    Posts:
    854
    Likes Received:
    0
    Location:
    oregon city
    Edelbrock 1406

    dont look or think about anything else. It's the simplest, and the ez'est.

    this is waht happened to me with experimenting

    [​IMG]
     
  16. SkysTheLimit

    SkysTheLimit 1/2 ton status

    Joined:
    May 23, 2003
    Posts:
    530
    Likes Received:
    0
    Location:
    Tampa, FL
    I stand corrected. I got the x70 part. Meatloaf said "Two outta three ain't bad".
     
  17. beater_k20

    beater_k20 Banned

    Joined:
    Dec 9, 2003
    Posts:
    10,276
    Likes Received:
    0
    Location:
    Elkhart, IN
    yes, your grandmother can tune an Edelcrap, BUT when it comes to getting off camber, the thing is a piece of crap. i had one on my TA, and the thing would act funny when launching hard, a can only imagine what it would do on any sort of real incline.
     
  18. beater_k20

    beater_k20 Banned

    Joined:
    Dec 9, 2003
    Posts:
    10,276
    Likes Received:
    0
    Location:
    Elkhart, IN
  19. MaxPF

    MaxPF 1/2 ton status

    Joined:
    Apr 13, 2006
    Posts:
    2,207
    Likes Received:
    0
    Location:
    Chandler, Arizona
    If I were you I would keep the TBI and get it to run right. The stock throttle body is plenty large, but the stock injectors probably don't flow enough fuel at full throttle. Also, you will definitely need a recalibrated prom. You will probably spend the same money as a good carb, but driveability and gas mileage will be better. If you're dead set on a carb, I say QJet as a 1st choice, and an AFB as a 2nd choice. The AFB sucks when operated at wierd angles, but since you said it is mainly a tow rig this shouldn't be a problem. AFBs are also cheaper and easier to tune than a QJet, but a properly tuned QJet will have the edge in mileage and driveability IMO. 750-800CFM is plenty for that motor.
     
  20. Russ

    Russ 1/2 ton status

    Joined:
    Feb 17, 2000
    Posts:
    509
    Likes Received:
    0
    Location:
    Summerdale AL
    The TBI doesn't run terrible, just bad enough to be aggravating. Plus I believe it is leaning out when I am towing. I have an overbored throttle body on it with AFPR, new injectors, fuel pressure gauge, two high flow fuel pumps etc.... All sitting on an edelbrock TBI manifold that I port matched to the heads. I have had a custom chip burned for it twice and have done a lot of tweaking on the fuel pressure, TPS and idle myself but just cannot get it to idle below about 1500 rpms if I bump the fuel pressure up enough to keep it from leaning out. I installed a 3 wire O2 sensor on it, but it doesn't want to stay in closed loop. As soon as I let of the gas when driving it goes back to open loop. I thought I may have a bad O2 sensor (Bosch), so I replaced it with a GM AFS74, but it does the exact same thing.
    I know my only logical step from here is to try and start datalogging and burning my own chips, or switch to a carb. I am more mechanically inclined rather than electronically so I don't think I would be very successful at trying to burn chips.
    Thanks for the help,
    Russ
     

Share This Page