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Thread Size for TBI

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Madbomber88, Jan 1, 2007.

  1. Madbomber88

    Madbomber88 1/2 ton status

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    Does anyone know what the thread size is on the Throttle body for the fuel line and return fuel line?

    I'm converting my 72 K20 to TBI and want to use Aeroquip's socketless tubing, but need to know what fittings to get, and they list them as NPT and AN. I know the threads are metric.

    Thank you in advance.
     
  2. fortcollinsram

    fortcollinsram 1/2 ton status

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    supply line is a 16mm saginaw fitting and the return is a 14mm saginaw fitting. That is what is on the end of the factory TBI fuel lines that go into the adapter on the TB. I dont know what kinda of thread the actaul TB is threaded for. All I know is that they use teflon flat washers to seal
     
  3. southernspeed

    southernspeed 1/2 ton status GMOTM Winner

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    You can buy the proper fittings from turbocity. They accept a push on hose.
     
  4. Madbomber88

    Madbomber88 1/2 ton status

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    Thank you, that's exactly what I needed.
    Next and last question: the feed line is 3/8 and the return is 5/16. Is there anything wrong with replacing the 5/16 one with a 3/8? I can only get the tubing in -6 (3/8) size. What will this affect?
     
  5. southernspeed

    southernspeed 1/2 ton status GMOTM Winner

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    It'll be fine if you can get it to seal on a 5/16 fitting. Earls do a braided black hose that is 8.9mm i'd which is between 3/8 and 5/16, that's what I use.
     

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