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Basic TBI mod success

Discussion in 'Tech Discussion' started by Jppr26, Feb 2, 2019.

  1. Jppr26

    Jppr26 Full Access Member

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    So the truck is a 87 v20, all stock, and I realised how much power it lacked while coming home with about a yard of sand in the back, so I started looking into some basic, easy upgrades. Found out the tbi is basically undersized and heads are restrictive for economic reasons, I will do heads and exhaust in the future but for now just the TBI unit.

    I started by going to the junk yard and pulling a compleat unit from another rig, in case what I did didn't work out I wouldn't be out one, took me about a hour to find one that was compleat, and when I got home I took it apart, ground down the air dams around the ports and widened them out as much as I felt possible, then wet sanded them down to 1500g and then polished them out. Rebuilt the unit, new gaskets and o-rings then slapped it on. No question it made a huge difference right off the bat that I could feel in the seat, much quicker acceleration, and even has a different sound 20190201_221023.jpg 20190202_115939.jpg
     
  2. Rusty Nail

    Rusty Nail Build the wall - deport them all! Supporting Member

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    Sweet!
    Your heads are likely cast #193 aka "swirl ports" and they are undesireable for a number of reasons. You are barking up the right tree for sure.

    I am aware of some other mods that can be made to the throttle body unit which will further improve it's performance.
    But to address the #193s would certainly be a great thing!

    https://www.thirdgen.org/forums/tbi/268064-swirl-port-heads-why.html

    http://garage.grumpysperformance.com/index.php?threads/193-swirl-port-heads.10579/

    #083 or #113 would be very efficient, cost effective upgrades - sourced from a Tuned Port engine found in an F-body.
    Bolt-on deal.
    I both support and condone the use of Z-28 or Trans-Am cylinder heads in your truck.
     
    Last edited: Feb 2, 2019
  3. Jppr26

    Jppr26 Full Access Member

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    I do believe I have the 193 swirl port heads but haven't fiscally looked, I got a guy at work who races dirt track who has alot of heads kicking around and is looking to see what he has that is willing to part with
     
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  4. Rusty Nail

    Rusty Nail Build the wall - deport them all! Supporting Member

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    Ahh sweet. He is certain to have some gems... that's awesome.!
     
  5. bucket

    bucket Super Moderator Staff Member

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    You also could have used a throttle body from a 454. The bores are actually larger.

    A couple more easy things you can do that really help, is an injector pod spacer (they used to be about 20 bucks) and advance the timing to 8-10 degrees BTDC.
     
  6. bucket

    bucket Super Moderator Staff Member

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    Nevermind about the spacer, I see in your picture that you already have one.
     
  7. Jppr26

    Jppr26 Full Access Member

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    The junk yard I went to charged me $45 for the compleat tbi, then it was around $35 for the rebuild kit, and a few hours of time to grind and polish. Well worth it,
     
  8. shanegtr

    shanegtr Full Access Member

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    Do the spacers make much of a difference on the 454? I've been thinking about what Im going to do with mine and I think the simplest option to make some decent power from mine will be to ditch the TBI and go carb - I'd like to go injected, but the setups I like are just a little out of my price range at the moment
     
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  9. 4WDKC

    4WDKC Full Access Member

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    You are on the right track, after the tbi mod it can quickly become not worth it. I did vortec heads and Cam by the time I was done it was almost $1000 to swap them and then you have to tune the efi so another 100-500 depending which route you choose. For that much I could have bought a 5.3/4l60 and swapped it in and been happier with the results.
     
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  10. Rusty Nail

    Rusty Nail Build the wall - deport them all! Supporting Member

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    I recently began to shop for a used Holley 300-66 (intake manifold).

    I've got 1.5" Flowtech headers and a K&N...prolly be alright. I think the injector spacer is likely a good deal too! I'll buy one when I run across it + add some hot ignition parts and call it good. :happy107:

    Likely cannot say no to Roller tip rockers though..:( I think that is excellent bang for the buck. In part because I believe it ensures even lift across all valves because the advertised ratio is FAR MORE accurate and uniform in the aftermarket than the factory pieces. The tolerances are simply too great for OE parts of 30+ years ago especially. Aftermarket rockers of whatever type are WIN/WIN in my book!

    I hear a used $25 LT-1 camshaft is a pretty hot ticket for a TBI engine. An LT-1 camshaft...Hell, people would likely GIVE THOSE AWAY and puttin one in don't cost no thousand bucks...Add the TPI heads? I'll try and drop em off with the homeboy LLOYD at HARDING MACHINE, tomorrow.

    Hmmmm..I wonder exactly what kind of power could be had!:rolleyes:
    Bet it could end up damned respectable compared to STOCK what, 190 horse? I don't even know...

    Anybody realized yet that I have already began to collect the parts lol?
     
    Last edited: Feb 4, 2019
  11. Billy

    Billy Member

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    I've spent enough trying to get my tbi to run right, that i could have bought a 6.0, done the swap, tune, and a years worth of gas. I'm done with tbi. It only has 7k miles if anyone is interested
     
  12. 4WDKC

    4WDKC Full Access Member

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    The holley intake isnt worth the cost, just buy a single plane carb intake and tbi adapter.. I literally did this swap a year ago.

    If the roller rockers are not 1.6 I wouldnt bother, your biggest deficit is the cam that with 1.5 roller rockers doesnt give more than .040 lift. The lt1 cam is good for 275 hp with vortec heads the desired year is 95, you will need roller lifters if you have a roller block, if not you need retro rollers. THe $1k I spent was vortec heads, used intake, flat tappet cam and lifters, gaskets, oil pump.
     
  13. 4WDKC

    4WDKC Full Access Member

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    if you have the equipment to burn your own chips contact davew on www.Gearhead-efi.com he, may be able to help you tune for a fee.. its a shame to waste the money you have spent when you are almost done.
     
  14. Rusty Nail

    Rusty Nail Build the wall - deport them all! Supporting Member

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    How can you resist?

    This is HALF THE PRICE of the Comp Cams rockers!
    Here.
    Fine!
    Holy shit that's a great deal!

    Take my money!

    Screenshot_20190204-112742_Chrome.jpg
     
    Last edited: Feb 4, 2019
  15. 4WDKC

    4WDKC Full Access Member

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    Easy, because on a stock cam tbi the gain will be minimal if any.
     

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