L18 8.1L swap resource thread

Discussion in 'The Engine Bay' started by Larry, Jun 14, 2013.

  1. RootBreaker

    RootBreaker 3/4 ton status Premium Member GMOTM Winner

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    on the top is an 8.1L starter and on bottom is my sbc...
    wow my sbc one is way bigger

    20201017_162235.jpg
     
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  2. Blue85

    Blue85 Troll Premium Member

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    I thought the same thing when I saw my 8.1L starter shared the same case as a 3800 starter. The larger diameter flex plate/flywheel does give the starter more leverage, though and the little starter had no problem cranking it. I had some questions about this but never posted up here. The 2003+ starter is a different style and it seems the block itself must have changed to accommodate.

    2003 up starter.jpg
     
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  3. Larry

    Larry 1/2 ton status Premium Member GMOTM Winner Author

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    Unlike LS engines, the nice thing about the 8.1L is it has the staggard bolt pattern and same ole 168 tooth ring gear GM has used for decades. Any starter from decades of BBC’s or SBC’s with the staggard bolt pattern and 168 tooth flywheel will work. Don’t feel obligated to spend crazy money to use an “8.1L” application starter

    From page 1 of this thread:

    - The L18 8.1L has the same foot print as older BBC engines and will bolt in the same as any other older SBC and BBC. In fact, the L18 will accept any exhaust manifold or header from older BBC engines. The starter motor from any older SBC and BBC for use with a 168 tooth flywheel will also fit the L18. Any transmission from an old PowerGlide, TH350, TH400 to Allison, to NV4500, etc. will bolt on to it as well.

    I like to run Denso 281-8002 starters on everything. The Denso starter on my Suburban’s 8.1 is the same exact starter that was on the TBI 5.7L before the swap. These starters aren't cheap but they will be the last one you ever buy. This is the starter UPS uses where it lives up to their punishment of starting hundreds of times a day. It will turn ring gear teeth into razer blades long before the starter wears out as the Rockwell hardness of the starter drive gear is harder (55) then the ring gear on the flywheel/flexplate which was around 35. Us guys would probably never see the ring gear teeth get worn down like they do.
    [​IMG]
     
    Last edited: Oct 17, 2020
  4. RootBreaker

    RootBreaker 3/4 ton status Premium Member GMOTM Winner

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    I googled 8.1L flywheel bolt torque and found this.. its soaked with imformation.. I have not looked at it other than briefly on my phone. Maybe useful to someone?
     

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  5. RootBreaker

    RootBreaker 3/4 ton status Premium Member GMOTM Winner

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    so... i see the small block motor mount holes are there.. I can use 1 bolt from the 8.1L bbc motor mounts but the other 2 that lineup are a smaller bolt. What size do I need?
    also the black plate that is on my sbc, guessing this is not used?

    20201025_151553.jpg
    20201025_152224.jpg
     
  6. RootBreaker

    RootBreaker 3/4 ton status Premium Member GMOTM Winner

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    20201028_131121.jpg ok tapped and cleaned the holes. Bracket bolted on fine.. sweet..

    now I saw the post to remove that piece if not using oil cooler... but do I just plug these on the block? and what pn do I need?
     
    Last edited: Oct 28, 2020 at 11:29 AM
  7. ZooMad75

    ZooMad75 #crawlabago Premium Member GMOTM Winner

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    Yep, just standard pipe plugs. But you need to pull the valve out above the oil filter. Larry updated the pics for that exact item while he got my 8.1 ready so all you got to do is go back and look at them in this tread. Pretty easy to see from the pics he took.
     
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  8. RootBreaker

    RootBreaker 3/4 ton status Premium Member GMOTM Winner

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    yeah i saw the pics..will remove that too...
     
  9. Rick Capito

    Rick Capito Registered Member Premium Member

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    Use the black plate if you are going to use the strut rods that go to the transmission lower cover
     
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  10. RootBreaker

    RootBreaker 3/4 ton status Premium Member GMOTM Winner

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    they actually hit the oil pan, so I cant put it on unless i put a small spacer in. I dont have the rods to my sm465 so I wasnt sure what this was for...thx...
     
  11. Wes Harden

    Wes Harden 1/2 ton status Premium Member

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    I don't believe sm465 had the braces.
    The plates could make a slight difference in eng trans t case angle, depending on mods. did on my fairly stock drive line.
     
  12. Wes Harden

    Wes Harden 1/2 ton status Premium Member

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    I don't believe sm465 had the braces.
    The plates could make a slight difference in eng trans t case angle, depending on mods. did on my fairly stock drive line.
     

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