D.O.A engine ... 350 tbi motor fixup/buildup

Discussion in 'The Injection Section' started by sweetk30, Aug 22, 2008.

  1. sweetk30

    sweetk30 selective wrench turner guy Premium Member

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    found all the info needed on lt1 swap to tbi motor on thirdgen

    link : http://www.thirdgen.org/techboard/tbi/262466-lt1-cam-digest-ultimate.html

    looks like we are good to go. even stock tbi springs will work.

    talked to scott ( 4x4high ) and we just need to figure out the springs in the am to see if newer z28 springs for roller use or old school z28 flat tap springs.
     
  2. bigblock72

    bigblock72 Elmer's glue taste tester Premium Member GMOTM Winner

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    The only possible snafu you may run into is the camshaft retainer. Some of the TBI blocks weren't tapped for the bolts for the retainer. Not a huge deal to drill and tap if necessary, just make sure you install the retainer before you bolt on the cam gear. Looks like your timing chain kit comes with everything you need (including the camshaft retainer and bolts) and should work fine.

    Your valvesprings should be fine for the low engine speed you'll see. TBI heads are done by 4500 or so which doesn't put much stress on springs, just make sure they're set up properly to get the seat pressure you need otherwise you will run into valve float issues. With that being said better valve springs are cheap insurance in case of an accidental over-rev and just general long term reliability as Scott pointed out.

    Make sure your rocker arm geometry is in the ball park, sometimes mixing and matching valvetrain parts can cause problems. Seems like every engine I build is a little different and I end up having custom pushrods made to make the rockers happy.
     
  3. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    I've already talked with him and found out that the only thing that needs to be done is the dowel pin needs to be cut shorter to use that cam. :thumb:

    I was correct though, that cam drives the water pump on the LT1 engine so the timing set (cam gear to be exact) is different.
     
  4. bigblock72

    bigblock72 Elmer's glue taste tester Premium Member GMOTM Winner

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    Yes the timing set is different between an LT1 (part# 12370835) and a regular GEN 1 small block (part# 12371043).

    According to the GM Performance catalog the dowel needs to be pushed in to .300" from the LT1 dimension of .620". Sounds like you can just take a small hammer and gently tap the dowel to the correct dimension. I've never done this personally so take it for what it's worth.
     
  5. sweetk30

    sweetk30 selective wrench turner guy Premium Member

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    update on the valve springs. called the place and thay said safe for the newer z28 roller cam use.

    big reason for checking was scott (4x4high) said if old style z28 springs thay would be wrong pressures and break / wear out to fast from the faster working roller cam movement.

    so now all is figured out the motor will start going together. keep checking back for more info.
     
  6. BGKYK5

    BGKYK5 3/4 ton status GMOTM Winner

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    Yessir, gladly. :waytogo:
     
  7. sweetk30

    sweetk30 selective wrench turner guy Premium Member

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    got the motor together few weeks ago. no major problems at all. parts whent in like a glove fit. i also installed new valve seals when swaping the springs.

    today cleaned up the outside of the motor and taped it off and sprayed semi gloss black paint on it. then bolted up my extra serp belt setup so its less i have to swap from the other motor for reinstall.

    will get pics sunday and post up. pics up now !!!

    new motor tbi350 001.jpg

    new motor tbi350 002.jpg

    new motor tbi350 003.jpg

    new motor tbi350 004.jpg

    new motor tbi350 005.jpg
     
    Last edited: Oct 12, 2008
  8. sweetk30

    sweetk30 selective wrench turner guy Premium Member

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    more pics

    new motor tbi350 006.jpg

    new motor tbi350 007.jpg

    new motor tbi350 008.jpg

    new motor tbi350 009.jpg

    new motor tbi350 010.jpg
     
  9. sweetk30

    sweetk30 selective wrench turner guy Premium Member

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    custom modifyed stock throttle bracket to work on carb intake and give me 100% full throttle.
     
  10. BGKYK5

    BGKYK5 3/4 ton status GMOTM Winner

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    Where'd you get the TBI adapter?
     
  11. sweetk30

    sweetk30 selective wrench turner guy Premium Member

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    ebay.

    and it can be used for front mount or back. and can also run tbi unit backwards.

    and thanks eagle mark. i did make sure it was sealed with good gaskets and any un used holes were pluged good.
     
    Last edited: Oct 13, 2008
  12. eagle mark

    eagle mark 1/2 ton status

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    Quote:
    Originally Posted by BGKYK5 [​IMG]
    Where'd you get the TBI adapter?

    ebay.

    When you install in permanently use sealer on both sides of gasket and make it permanent. These are notorious for vacuum leaks.
     
  13. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Unless you know someone who makes them on a CNC. :D
     
  14. scouthead

    scouthead 1/2 ton status

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    Lookin good. When's it gonna fire?


    Those headers going on a truck with an automatic? My cheapo Pacesetters look identical to those, but don't think they will clear my slave on the sm465... :doah:
     
  15. sweetk30

    sweetk30 selective wrench turner guy Premium Member

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    well back from the DEEP dead pile just over 10.5 years of storage :zombie18:

    friend was looking for a good short block and i still have this so i stripped all the good stuff and checked the #1 main and rod bearings and thats were stuff went down hill fast . i never heard this run and told was driving plow truck in the vehicle it was pulled from . i noticed it was a reman engine from the reman tags well it must of been neglected bad a bit as the copper was showing on the bearings bottom halfs . :zombie4:

    so i guess if someone wants a .040 over 350 block to start with then there good to go . but she needs more work than he was going to want to put in to it . so long story short dont trust anything unless you know its history and hear it run . only thing i am out is time and few gaskets . as i got the motor in a swap for few hr's labor time deal .

    i think some parts will now make there way in to a i know good running 350 or the roller rockers swap on to my new L31 vortec in the budget beater build not sure yet .
     
    Last edited: Apr 14, 2019 at 5:00 PM
  16. 1-ton

    1-ton 1/2 ton status Premium Member

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    One thing I noticed on this old thread is that if this engine has the stock TBI swirl port heads you cannot use the roller rocker arms you bought for it, unless you installed push rod guide plates with screw in rocker studs (old TBI heads are not worth that kind of money in machine shop work). Those old TBI heads require self aligning rocker arms. Self aligning roller rocker arms do exist.
     
  17. sweetk30

    sweetk30 selective wrench turner guy Premium Member

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    Them ones i got are self aligning note the part no. and pics with the guides on the rollers .
     
  18. 1-ton

    1-ton 1/2 ton status Premium Member

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    OOPS! did not look at the picture close enough. I remember doing a search for some self aligning roller rockers, and the only company I could find that made any was Scorpion. I did not know that COMP cams made some too.
     

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