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TBI base timing

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Mastiff, Jun 17, 2004.

  1. Mastiff

    Mastiff 1/2 ton status Premium Member

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    This is a lame question, but... I'm trying to set the base timing on my new TBI for the first time. This is a standard Chevy 350 TBI system. I have two questions, (1) Where might I find this "timing connector", and (2) what is normal base timing for a Chevy 350 with TBI? I thought I read zero degrees, but I can't find it anywhere on-line.

    Is there a good manual for this type of thing? My Chilton and Haynes manuals cover model years with TBI, but they don't talk about anything useful related to EFI.
     
  2. Hossbaby50

    Hossbaby50 3/4 ton status

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    Normal base for my TPI is 6* BTDC. The timing wire is connected to the dist module, I don't remember which wire offhand though.

    Harley
     
  3. Thunder

    Thunder 3/4 ton status

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    Base timing is 0. On TBI
    The timing bypass wire is located on the drivers side firewall near the power brake booster. It is a tan wire with a with a black stripe and a weather tite connector that comes out of a big wire loom. DO NOT Disconnect the Dist module wires!
    Pull the weathre tite conector apart
    start truck.
    set timing top 0
    shut down truck reconnect the connector.
    While the connector is apart the check engine light will come on
    After the connector is plugged back togeather it should go out.
    This is for a Blazer, Trucks and newer TBI (92+) have the bypass wire in diferent locataions.
     
  4. 88Silverado

    88Silverado 1/2 ton status

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    Exactly what he said /forums/images/graemlins/thumb.gif
     
  5. Mastiff

    Mastiff 1/2 ton status Premium Member

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    Thanks! /forums/images/graemlins/thumb.gif
     
  6. fortcollinsram

    fortcollinsram 1/2 ton status

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    TBI 350 base timing is 0*
    TBI 454 base timing is 4*


    I run my base timing on my 454 at 6* with good results...

    Chris
     
  7. Thunder

    Thunder 3/4 ton status

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    FYI You can run more than 0* base timing. I run 4-5 degrees advance on my 89/350. But I have to use at least 89 octaine and my fuel pressure is up around 14 PSI. If I use lower octaine knock sensor retards the timing to prevent pinging and I dont get as good of performance or MPG.
     
  8. ahx

    ahx Registered Member

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    i know this is an old subject but i jsut did a rebuild with a little more juice on my 88 tbi 350. Im having problems with black smoke and it seems to be running rich. I have the stage 1 chip in it. I had the pressure up around 14psi but it runs even worse like that. i have had the timing from 0 to 10 degrees btdc and nothing seems to help. btw i have a holley replacement tbi witht he 2 inch bores. I jsut oredered new 454 injectors for it as one seems to be leaking after the truck is turned off. could htat be the whole issue?
     
  9. SF87K5

    SF87K5 1/2 ton status

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    do you have the holley 670 TBI for it? if so you might need to get a different chip, you might even have to have one custom made.
     
  10. ahx

    ahx Registered Member

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    ah crap I just bought this chip too from tbiships.com
     

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