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Thread: Rebuilt TBI Fuel Injector (not the throttle body)

  1. #1
    Fuel Injected!
    Join Date
    Mar 2013
    Federal Way, WA

    Rebuilt TBI Fuel Injector (not the throttle body)

    I have a 9C1 5.7. I have the injectors cleaned when I rebuilt the TBI. I just bought a set of serviced and flow matched injectors off eBay. The seller has a 99.5 rating with thousands of sales. I was disappointed today when the injectors arrived. The P/N had been removed, but I could still read it, 34085. They are off a mid 80's Caddy 4.1. When I contacted the seller he said they disassemble the injectors and rework them for the proper application. Looking closely at both ends I can see that they actually did take them apart and restaked the ends. I had no idea that was possible.

    Is anyone familiar with this process? Any idea what that would do to the longevity of the unit? Thoughts? Trust the injectors? Send them back? I am leaning towards using them, but I want to find out more about the process.


  2. #2
    Fuel Injected!
    Join Date
    Mar 2012
    did it come with a flow report? the only way to know would be to get them flow tested. there was a guy a few years back on TGO that was modifying tbi injectors for higher flow (above gm specs). i believe rbob (of DynamicEFI) tested them. I am sure it is possible to take them apart and modify but I wouldn't believe it without a flow report from a known source (witchhunter etc)

  3. #3
    Super Moderator Six_Shooter's Avatar
    Join Date
    Feb 2011
    TBI injectors are VERY easy to modify for increased flow. The top has a threaded stud that is usually staked or tack welded and if you grind the stake or weld off, you can twist the stud and change the flow rate. I've done this on a couple TBI vehicles now. Yes, you're kinda guessing at the flow when you do this without reflowing them, but that's where tuning comes in. *shrug*
    The man who says something is impossible, is usually interrupted by the man doing it.

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