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Thread: Which TBI system is better?

  1. #16
    Fuel Injected! blue68deville's Avatar
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    I'd keep them, the ends at the tb are hard to duplicate. You can always shorten them later.
    If it has the braided lines then definitely keep em. They're hard to find.
    68 Cadillac, 472 & TH400 w/7.4L TBI and EBL **sold**

    93 K1500 short step, 5.7 & NV4500 and EBL

    68 C10 LQ4/TKO swapped

  2. #17
    Super Moderator Six_Shooter's Avatar
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    The fuel lines can be made, however, they use a special fitting that GM liked to use them (It's called a Sawginaw fitting). Usually this requires fairly expensive flaring tools to make this fitting. Mine cost me about $350 on a deal. So you may want to pull the lines and have them handy to use.

    On the flip side many parts stores sell "repair ends" with these fittings and can be used in a swap situation like this. They come in various lengths from 6" to 18".
    The man who says something is impossible, is usually interrupted by the man doing it.

  3. #18
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    Good info, I will pull them if I can.
    So, I am taking the TBI unit, Harness(marked every wire or left parts attached), sensors, Air filter, air injection setup(not the exhaust manifolds), smog pump, EGR, pipes and valves.
    I managed to remove the whole TBI setup, except the coolant pipe that comes out of the back of the TBI unit... could not budge the fitting and could not release the hard pipe from the back of the head, so I cut it.

    Removed the whole front accessories setup inc pulleys, alternator, smog pump, AC compressor, and brackets.

    Chased all of the wiring thru the firewall on the pass side and released it from the ECU and pulled it back thru the firewall cleanly. Took the ECU out.
    Could not get the wires out from the ECU to ALDL out, so I cut them each end as long as I could. I think I would have to lengthen that anyway.

    Couple of questions...
    Should I remove the Knock sensors? There looks to be 2...
    I removed the harness as far as the fuse block on the drivers side firewall... how do I release that, or can I cut it off????

  4. #19
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    Still working on this.

    Found and labeled the 1990 ECU and the 1987 ECU.
    Both came off R2500 3/4t 2wd suburbans with TH400's

    The 1990 is a 1227747?


    And the 1987 is also a 1227747?


    Does that mean that they are identical... or did I read the wrong number

  5. #20
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    Quote Originally Posted by KeyAir View Post
    Still working on this.

    Found and labeled the 1990 ECU and the 1987 ECU.
    Both came off R2500 3/4t 2wd suburbans with TH400's

    The 1990 is a 1227747?


    And the 1987 is also a 1227747?


    Does that mean that they are identical... or did I read the wrong number
    They are identical ECMs.

    The 4 letter "code" that differs on each one , ANTY and AFTH , are the broadcast codes for the calibration , it is the larger of the two chips you will find under the cover , this is the only difference between the two units you have there.

    TOM
    1994 3500 Dually , 502 (509) , 264HR , Edelbrock MPFI , PFI '7427
    1992 S-10 434 SBC/Tremec - '7427
    1986 Monte Carlo SS
    1984 S-10 , SAS, 496/700R4/205 , D44/14BFF -'7427
    1980 Z-28 496/700R4
    1979 Corvette 496/700R4
    1977 Olds 98 Regency 403/700R4

  6. #21
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    Thanks Tom!

    So here is what I am thinking...
    The 1987 was my own vehicle for 15 years and I know it ran fine, but the 1990 was a non runner, so I have no reference point.

    If I use the 1987 ECU, TBI, and smog gear, and as I have a copy of the title I can say that this is my engine swap for the California smog referee.
    However, I would prefer to use the full, single serpentine belt drive from the 1990.
    I will assume for now that the smog pump, and AIR system will be the same connections and function as they ran off the identical ECU...

    The 1990 accessory drive looks like this...


    And the 1987 was a mishmash of serpentine from crank to Smog Pump and Alternator, and V belts for PS, and AC... like this.
    Last edited by KeyAir; 03-09-2015 at 10:18 PM.

  7. #22
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    Just be sure if you use the 90 accessory drive you get the correct water pump when you replace it , the 90 setup with one serpentine belt uses a reverse rotation water pump whereas the 87 multi belt setup uses a standard rotation water pump.

    I use the Edelbrock aluminum pumps for replacements on all of my stuff , good quality and improved cooling.

    I would save that power steering pump and bracket setup off of the multi belt (87) engine , they go for some good money as they are sort of hard to find for the Camaro / Chevelle guys swapping to the BBC from a small block.

    ECM will control the smog stuff with either belt setup . Do you absolutely need to run the smog pump ?

    TOM
    1994 3500 Dually , 502 (509) , 264HR , Edelbrock MPFI , PFI '7427
    1992 S-10 434 SBC/Tremec - '7427
    1986 Monte Carlo SS
    1984 S-10 , SAS, 496/700R4/205 , D44/14BFF -'7427
    1980 Z-28 496/700R4
    1979 Corvette 496/700R4
    1977 Olds 98 Regency 403/700R4

  8. #23
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    Sorry for the delay in responding...
    Yes, the Smog pump MUST be there to make this pass smog.

    I am working toward this conversion now, and have more questions.

    What "Size" fuel feed and return pipes will I need? I have a return pipe, but it looks small diameter.
    Last edited by KeyAir; 11-20-2015 at 05:00 AM.

  9. #24
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    So, am in the ongoing march toward the TBI/4L80E swap.

    Was at the Junkyard on halfprice day, and grabbed this... for $18...

    16197427 BJYL ecu and about as much wiring as I could reach from a "95 Suburban.


    Did I get the right one... a TBI/4L80E controller?
    Will this run a 454 TBI from 1987/1990?
    I know I will need more stuff, like the plug for the 4L80E too, but I was looking for the DRAC, and could not find it!
    Where is teh DRAC???

  10. #25
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    Do you already have the 4L80e? The '91-93 is a bit different than the later versions and should be used with the '7060 ECM, any others would use the'7427 you grabbed. It's much easier to start with a complete 4l80e harness to rework rather than trying to build it from scratch.
    1973 K-5 Blazer, TBI 350, TH400, 1 ton axles & 38" SSRs'
    1975 280Z, TBI 350, 700R4
    1953 M-38A1, TBI Buick 231
    1951 Ford Panel, 5.3 with 4L80E

  11. #26
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    I have the 4l80E, but i do not know what year it is... see my original post on page 1.
    I am aware of the "Force Motor" difference, so will keep that in mind when I rebuild it.

  12. #27
    Super Moderator Six_Shooter's Avatar
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    So what's the difference in the force motor that would cause one to need to change to a different PCM?
    The man who says something is impossible, is usually interrupted by the man doing it.

  13. #28
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    I forgot that you're here in California. As suggested earlier, it's probably best to go with the '7747 setup with the original trans to get it though the referee as an engine swap. Once you've jumped those hurdles, you can go back and swap in the '7427 and 4L80E.
    1973 K-5 Blazer, TBI 350, TH400, 1 ton axles & 38" SSRs'
    1975 280Z, TBI 350, 700R4
    1953 M-38A1, TBI Buick 231
    1951 Ford Panel, 5.3 with 4L80E

  14. #29
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    Quote Originally Posted by Six_Shooter View Post
    So what's the difference in the force motor that would cause one to need to change to a different PCM?
    I'm not an expert on it, but I believe that the force motor operates at a different frequency and has a cleaning cycle that the '7427 doesn't support. I've heard of people using the early trans with the '7427, but not sure how long they'll last like that.
    1973 K-5 Blazer, TBI 350, TH400, 1 ton axles & 38" SSRs'
    1975 280Z, TBI 350, 700R4
    1953 M-38A1, TBI Buick 231
    1951 Ford Panel, 5.3 with 4L80E

  15. #30
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    Ok, things just changed up.
    I have to have the Motorhome up and running in 2 weeks to move it.
    Put the Quadrajet on and its just not running right.

    Can I do the basic TBI conversion using the '87 stuff in that time frame?
    I need a running vehicle, not smog compliant in 2 weeks.

    Tomorrow I can go get the box that I stashed the '87 Throttle body/wires/ecu etc.
    The '90 harness I have may be more complete, so maybe I should use that as the ECU is the same...

    Not worried about smog pump and cats yet, unless they are needed to run the engine.
    I will need to pull the LH banks header to install the O2 bung.

    Possible????
    Last edited by KeyAir; 11-30-2015 at 10:26 AM.

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