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TBI on a 304???

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  • TBI on a 304???

    I have a 304 w/ 2bbl holley 7448 carb. Right now I'm pulling 20 vaccum and 170 psi compression even all around. Is it going to be worth it to do a TBI conversion? Also, will the 670 CFM Pro Jection system be too much CFM air for my 304?

  • #2
    I am converting mine using GM fuel injection parts like Bill and Mark-Eagle and the others. Mine (800A w/304) is being converted mainly for the driveability/mpg of the fuel injection. Don't even get me started on electric chokes!!! I don't crawl on the rocks (yet), but you can't beat injection for off camber driving. I like the idea of jump in turn the key and drive off!! As for the Projection issue I can't really help, but someone will soon. Wish ya luck!
    My "Disasterpiece"
    1970 800A 4X4,HFI'd,304,B/W,27,44,3:73,28's.
    The rest are in my 25 year plan!

    My "Ruedh"
    FREE 1972 1110 4x4,V8(?)727,205,44 drum/60/3.54's,small cheap tires.
    LOOOOADS-O-RUST!! Donor body located. Not!! JY owner played the "crusher value" card. : angry:
    NON-working rear window. Need info!!!

    www.northtexasbinders.com

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    • #3
      Your CFM question makes me think........
      What is too much CFM?
      If the intake, runners, and valves will only flow a certain amount of air, then can the TB be too big?
      If you use a closed loop system that constanly monitors the amount of fuel to add to maintain a set AFR than would it matter?

      I think if the system was tuned for your motor it would be fine.
      I'm not a big fan of the old holley injectors.
      But you could retro fit some GM inj on a holley TB or I'm sure AFI would sell you one already converted.
      If you go holley, make sure it is tuneable and has the closed loop option.
      My $.02
      Bill USN-1

      COMMITED TO TEACHING PEOPLE THE "PROPER" WAY TO EFI
      HAMILTON FUEL INJECTION
      May be the answer to all your fuel injection needs!
      Learn to do it right.

      Comment


      • #4
        I know somebody else has probably asked this, but I'm just so new to this whole fuel injection thing. I've been a carbureted man all my life and its all I know and understand. What GM TBI and distributor would I need to do the conversion? I'm always up for better driveability and mileage, and carburation just isnt cutting it for my needs anymore. HELP!!

        Comment


        • #5
          Rather than starting over, I will refer you back to the main FI page on this site. There is a lot of info on systems, dist, links additional info.
          Also If you spend a little time reviewing the post here in the FI forum most all of your questions will be answered.
          Bill USN-1

          COMMITED TO TEACHING PEOPLE THE "PROPER" WAY TO EFI
          HAMILTON FUEL INJECTION
          May be the answer to all your fuel injection needs!
          Learn to do it right.

          Comment


          • #6
            Will do, thanks boss!

            Comment


            • #7
              Too much CFM?

              The answer to this is yes and no. Where it counts is at idle and transient (stepping on the pedal) conditions. Cruising down the road the engine will only use what the hardware will allow it to use for air, you will have your foot positioned to allow that level of air flow. Where it makes a difference is on an accell. The inertia of the air coming in with a big gulp will cause a lean spot and can cause a sag, backfire, etc. if it is not complimented with the proper amount of fuel to balance the air/fuel ratio properly. there is a point where there is to much and no amount of fuel can compensate for it.

              With a carburetor we called this a pump shot, with fuel injection we call it accelleration enrichment. If you have looked at a file you will see that a 4.3L engine has a lot larger A.E. fuel enrichment than a 5.7L. The bore sizes on the throttle body are the same but the volume of air that the engine can handle is totally different. Therefore more fuel needs to be added to the air to provide a balanced air/fuel ratio.

              If there is to big of a bore it may also allow to much air at idle which does not allow you to control your idle speed.

              Comment


              • #8
                hmmmmm i guess this injection stuff is to complicated for me can i get TBI on my stock 304? or would it be cheaper better to switch to a 345 392?
                www.rogue4x4.com

                Comment


                • #9
                  The size of the engine does not really matter except for the components you chose.
                  305 chevy parts for a 304, 350 chevy parts for a 345.

                  I think you may be jumping in the deep end of the pool and you need to go back to the shallow end and work your way in.

                  Go to the main FI page and read the FAQ there. AFI has a lot of good info there.

                  HTH
                  Bill USN-1

                  COMMITED TO TEACHING PEOPLE THE "PROPER" WAY TO EFI
                  HAMILTON FUEL INJECTION
                  May be the answer to all your fuel injection needs!
                  Learn to do it right.

                  Comment

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