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4L80E to Mark IV

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  • 4L80E to Mark IV

    Can someone tell me what I need to do to attach a 4L80E out of an '01 3/4 ton Silverado with a 6.0 LS 2WD to a 70's 454 block? Is a spacer needed between block & bellhousing? What flexplate and does nose of convertor fit in crank? What Starter? Any help is greatly appreciated.

  • #2
    from what I've read on the http://www.chevelles.com/ and the http://67-72chevytrucks.com/
    you need a engine to block spacer/a flexplate to converter spacer.. and use a mini starter for any big block..
    good luck.. not sure if a 4l80e used in the 8.1 big block trucks used a different bolt pattern, or if the info on the sites are wrong..
    good luck

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    • #3
      OM - call Brentsen's (I think that's spelled right). They're in the NW (Oregon, I think) and are the gurus of trans adaptors. Worth a Google.

      Dan

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      • #4
        Thanks for the info guys. Bendtsen's in Mn. are into older engines to modern trans adapters-great for things like nailheads and early hemis. The web sites don't answer my specific question or have source for spacer. GM performance parts has adaptors but only for one piece rear main seal. I'll get it figured out.

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        • #5
          Do you have the transmission yet?
          My fabulous web page

          "If it don't go, chrome it!" --Stroker McGurk

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          • #6
            Oh naturally. Should check things better before I purchase parts. I have the trans and a 3K stall convertor.

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            • #7
              Then do some measuring. Push the converter in the trans all the way, measure from the bolt pad on the converter, to the front of the trans case.

              I'll measure a normal th400 for you to compare
              My fabulous web page

              "If it don't go, chrome it!" --Stroker McGurk

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              • #8
                Thanks. I may have gotten in a hurry with this as I don't have access to trans at this time-its at a friends sons house getting rebuilt. I am trying to gather parts up ahead of time as it never works out to scramble for things at the last minute. One of the things I really need to know is if a stock type flexplate will work so I have it when I balance the engine.

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                • #9
                  Originally posted by OldMachinist View Post
                  Thanks. I may have gotten in a hurry with this as I don't have access to trans at this time-its at a friends sons house getting rebuilt. I am trying to gather parts up ahead of time as it never works out to scramble for things at the last minute. One of the things I really need to know is if a stock type flexplate will work so I have it when I balance the engine.
                  you'll fit in quite nicely here

                  and it's unlikely the stock (the the 4l80e) flywheel will work since it's attached to the one piece rear main seal flange - but I'm sure you knew that - were it me, I'd take the stock flywheel and hold it against the torque converter to see if the bolt holes line up.... IIRC they used the diesel (6 bolt) style, which also are available from the peanut port motors. Whether or not that 6 bolt spacing is the same as the 6 bolt for the 4l80e is not within my knowledge.
                  Last edited by SuperBuickGuy; November 22, 2011, 11:46 AM.
                  Doing it all wrong since 1966

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                  • #10
                    I can answer that question, I have a 4L80E from a 1994 suburban with a 454, and the six bolt flexplate from a 1979 suburban (two piece rear main seal engine) lines up with the holes in the converter. Which I figured it would.

                    I guess the only issues are if the LSx case is a different length than the 454 case, which I doubt, and if you need a 454 converter instead of the LSx converter.
                    My fabulous web page

                    "If it don't go, chrome it!" --Stroker McGurk

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                    • #11
                      From what I remember reading, the 4L80E stayed with the older SBC/BBC bellhousing pattern and depth so for the 6.0 truck motors they had to put in a flexplate spacer to get it to work. I think it's the same trick used to put a TH200-4R, TH700R4, TH400, etc... behind a Gen III/IV. Best I know the 4L80E cases stayed "old school" while the updated 4L85E actually had a redesign.

                      I only have a 96 (classic cooler line configuration) 4L80E so can't say about the newer ones with personal experience.
                      Central TEXAS Sleeper
                      USAF Physicist

                      ROA# 9790

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                      • #12
                        Man I hope you're right. I have seen the spacers advertised but without a good description of what they are for. The guy working on my trans didn't really have the answer but said they all take the same convertor. I will have to find out for sure when I have all my parts together I was just trying to get a jump on gathering stuff up. Thanks to everyone for their input.

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                        • #13
                          It will bolt right togeather. The spacing of the bellhousing on a 4L80 was never redesigned to work with a LS engine. To put one behind a LS, the factory adds a spacer to the rear of the crank flange to pick up the pilot of the converter.

                          There are a couple different flywheels available, and you will need to make sure you have the correct one. Also, all factory 4L80 converters are 6 bolt. You can use only 3 if you want.

                          I have one behind the LSA in my Jeep. I had to make the spacer for mine, and modify the flywheel, because the LSA engine has a 8 bolt crank flange.
                          Last edited by Mike Copeland; November 23, 2011, 09:20 AM.
                          If it was easy, everyone would do it.

                          Brighton, MI

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                          • #14
                            That all makes sense to me. Sounds like he just needs a flexplate for a 70s 454. They all have at least 3 holes that line up, don't they? or specify one for a late 70s 3/4 ton just to be sure
                            My fabulous web page

                            "If it don't go, chrome it!" --Stroker McGurk

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                            • #15
                              I e-mailed TCI tech support and Mike is right. They said trans bolts right up and works with stock flexplate but couldn't say if convertor stub fits my crank. Thats easy if too big just bore crank, if too small I'll turn a bushing to make fit. Thanks for the input and have a Happy Thanksgiving! Now I have to figure out if stroker crank is internally balanced like I think or if I need an externally balanced flexplate. On the downhill side as far as this issue goes.

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