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Thread: 454 TBI for '98 350 Vortec

  1. #1
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    454 TBI for '98 350 Vortec

    I have purchased a used 454 TBI for use on a '98 350 Vortec. I am at odds on which injectors to use in the throttle body. Right now it has the 17104288 injectors but am uncertain as to their condition. Need to order replacement injectors. Have ordered adjustable fuel pressure regulator for the throttle body. Have two choices of injectors, the 17104288 or the 5235231. They are as follows from what I have found on the Internet. Also ordered a Bosch higher pressure fuel pump than the stock 15psi pump. Then should be able to adjust to some value pressure that should work. May have to purchase different poundage fuel regulator springs to accomplish this. There is a Vacuum referenced fuel pressure regulator available by way of Ebay. This seems to be counter productive to use as the ECM should make the fuel corrections via MAP values.

    5235231 - Red / Blue - 80pph - 7.4L / 454 - 88-90

    17104288 - Pink / Purple - 46pph @13psi - 7.4L / 454 - 94-95 *NOTE: Came with 30 PSI regulator used @ 26-32psi for 67-72pph

    These flow rates are a safe bet average @ 12-13psi, be aware that actual flow can vary by greater than 10% throughout production.

    Any advice or comments on this and course of action would be greatly appreciated.

  2. #2
    Super Moderator dave w's Avatar
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    One option you might consider is having the 17104288 serviced and flow tested ($16 each) by Mr Injector: http://www.mrinjector.us/ I've had several sets of TBI injectors serviced and flow tested by Mr. Injector, I highly recommend him. On a couple occasions, I requested Mr. Injector to flow test the TBI injectors I sent him at a specified fuel pressure, usually 18 psi. Maybe have the 17104288 injectors serviced and flow tested @ 30 psi? This option is usually half the price of a single new TBI injector, but you get two serviced injectors that work like new.

    dave w

  3. #3
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    Since you've already ordered the pump and regulator, I'd probably go with the 5235231 injectors. You'll be able to get more fuel at lower pressure from them, which might give you a little more flexibility. I might be interested in your old injectors if you want to get rid of them.

    Are you going to use a throttle body adapter or a TBI intake? The factory 454 adapters were built for the older throttle bodies, so the gasket surfaces don't match up around the idle air passages with the newer 454 TBs. You might want to build up that area on the adapter with epoxy or something if you're going that route to prevent vacuum leaks.
    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

  4. #4
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    Thanks to both Dave W. and fastacton. Dave, thanks for the referral to mrinjector. Will request that he test at 20 and 30 psi after reconditioning the injectors. With his Lb/Hr numbers at these psi's can get and idea of how they are working. Then can interpolate what would be a test fuel pressure to set the adjustable regulator at. The higher pressure injectors provide better atomization of the air/fuel mixture. Yes, replacement injectors are expensive! Again, thanks.

    Fastacton, I have a Trans Dapt TBI to 4150 carb adapter. It had to have the 2 bores enlarged to maximize air/fuel from the throttle body. The same will have to be done to the aluminum 4150 Intake Manifold. Will watch carefully, the mating of the throttle body to adapter and adapter to 4150 manifold to make certain there are no vacuum leaks. Again, thanks.

  5. #5
    Super Moderator dave w's Avatar
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    I'm using a 1994 7.4 liter Throttle Body on my 93 K1500 / 5.7 liter engine. I bored the factory 5.7 liter intake to accept the larger throttle blades of the 7.4 liter, then used the an aftermarket adapter, see attached pic.

    dave w

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    Dave:

    After boring the 5.7 liter intake, what part number injectors were used and what pressure fuel pump is being used?

    Thanks very much for all the information. I have sent the injectors off to mrinjector for reconditioning with additional request to test at 20 and 30 psi and document the results and send back with the injectors.

  7. #7
    Super Moderator dave w's Avatar
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    Quote Originally Posted by rsicard View Post
    Dave:

    After boring the 5.7 liter intake, what part number injectors were used and what pressure fuel pump is being used?
    I'm using "Cop Car" injectors 17084327. I'm using the stock fuel pressure (about 13psi) from the 93 K1500 5.7 liter throttle body installed on the 94 7.4 liter Throttle Body.

    For the most part, I "Cloned" the early 90's police caprice 5.7 liter engine specifications when I replaced the engine in my 93 K1500.

    dave w
    Attached Images Attached Images

  8. #8
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    Dave W.

    Thanks very much for your posts here. Very interesting. I really enjoy them as I am a real gearhead and versed in electronics also.

    Removed the 7.4 liter injectors from the throttle body and sent them off to mrinjector to be reconditioned. Ordered and received adjustable fuel pressure regulator kit. The pressure regulator on the 7.4 throttle body has an adjustment that is a security torx screw. Found a torx bit that I can use to adjust it. Awaiting return of injectors from mrinjector.

    Not in a hurry to change the engine over to a 350 Vortec. Would like to get more familiar with TunerPro RT tuning of the 16197427 ECMs. Also have a 1994 7.4L Suburban that has the 16197427 ECM. Installed an Edelbrock TBI to port injection manifold on it. The only modification to the ECM was the binary supplied in a chip by Edelbrock. Purchased the APU1 from Moates and flash memory chip from them also. Need to go further in tuning the '94 Suburban also. It was bored .030 over and stoked another .25 inch to 4.25 stroke to 496 cu in. Installed Edelbrock 454 Oval Port cylinder heads which give it a much better static compression ratio. Yet the Edelbrock intake manifold is for Peanut Port GM 454 cylinder heads! So I need more time tuning both the '94 Sub and '95 pickup and get MUCH more familiar with the process.

  9. #9
    Super Moderator dave w's Avatar
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    Quote Originally Posted by rsicard View Post
    Also have a 1994 7.4L Suburban that has the 16197427 ECM. Installed an Edelbrock TBI to port injection manifold on it. The only modification to the ECM was the binary supplied in a chip by Edelbrock.
    http://www.gearhead-efi.com/Fuel-Inj...Information-0D
    Post #6 has the '7427 TBI to MPFI .zip file.

    With a couple resistor mods inside the '7427 PCM, and a jumper wire mod to the Memcal, a '7427 will operate 8 saturated (high impedance 14 ohm ~ 16 ohm) injectors every 4 Distributor Reference Pulse (DRP) ... same as the older '7730 / '7727 TPI ECM operates 8 saturated injectors.

    dave w

  10. #10
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    Dave: Now I believe I understand what was done to the 93 K1500. The 5.7 liter fuel top half of the throttle body was used on the lower half 7.4 liter portion of the throttle body along with the "Cop Car" 17084327 injectors from same. Very clever idea. Already have 17084327 injectors on order from Ebay. Would like to do the same as you have done. Mine will be going on a salvage 5.7 liter Vortec engine. Is there a binary file available for this combination? Please advise. Thanks.

  11. #11
    Super Moderator dave w's Avatar
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    Quote Originally Posted by rsicard View Post
    Dave: Now I believe I understand what was done to the 93 K1500. The 5.7 liter fuel top half of the throttle body was used on the lower half 7.4 liter portion of the throttle body along with the "Cop Car" 17084327 injectors from same. Very clever idea. Already have 17084327 injectors on order from Ebay. Would like to do the same as you have done. Mine will be going on a salvage 5.7 liter Vortec engine. Is there a binary file available for this combination? Please advise. Thanks.
    I don't think there is a "close enough" factory binary file for the combination of parts listed above. The timing tables, spark tables and injector parameters need to be "customized" into a stock binary to get close. Then tuning will be required to optimize the performance.

    dave w

  12. #12
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    Quote Originally Posted by dave w View Post
    I don't think there is a "close enough" factory binary file for the combination of parts listed above. The timing tables, spark tables and injector parameters need to be "customized" into a stock binary to get close. Then tuning will be required to optimize the performance.

    dave w
    Thanks for the reply. I am going to try the binary that is already in the ECU for the 1995 Chevrolet 5.7 liter. Hope that will at least get it running. Then need to tune timing tables and injector parameters to optimize performance. Do you think the stock binary will be close enough to get it started? Please advise. Thanks.

  13. #13
    Super Moderator dave w's Avatar
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    Quote Originally Posted by rsicard View Post
    Thanks for the reply. I am going to try the binary that is already in the ECU for the 1995 Chevrolet 5.7 liter. Hope that will at least get it running. Then need to tune timing tables and injector parameters to optimize performance. Do you think the stock binary will be close enough to get it started? Please advise. Thanks.
    The stock binary will most likely get the engine running, but not drive-able? I strongly recommend using TunerPro RT at startup to determine if it's drive-able!

    dave w

  14. #14
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    Quote Originally Posted by dave w View Post
    The stock binary will most likely get the engine running, but not drive-able? I strongly recommend using TunerPro RT at startup to determine if it's drive-able!

    dave w
    Just got done installing a fuel pressure gauge on the inlet line of the stock 1995 throttle body and engine. The pressure gauge reads 7.5 to 10.0 psi. Perhaps during the engine swap to a 5.7 liter 350 Vortec, the bowl of the fuel pressure regulator should be changed out to an adjustable one which I have from a 454 throttle body. Use the stock spring and adjust the fuel pressure up to 12-13 psi? Would appreciate your thoughts on this. Right now with the 1995 350 engine, the idle BLMs are on the rich side. Same holds true with the off-idle BLMs.

    Not sure what the results will be using the stock throttle body on a 350 Vortec with a 4 barrel manifold with TBI adapter plate and appropriate fuel pressure. This way I do not have to remove the fuel tank and change the fuel pump. The Vortec cylinder heads are more efficient. Not sure if they will want more or less fuel than the stock 1995 350 engine. Getting everything lined up for the engine swap. Really want it to go well. Here's hoping.

  15. #15
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    Further planning on raising or lowering idle and off-idle VE table by a fixed percentage to start with. Not sure of the correlation of VE tables to injector pulse width. Perhaps you can explain what your thoughts are on these two aspects.

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