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My first ever engine rebuild: Turbo slant six Mk IV

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  • My first ever engine rebuild: Turbo slant six Mk IV

    So, I've done an LS swap project, and I've gone the "throw a turbo on an internally stock motor" route - but here's the first time I have tried a full engine rebuild. This is the fourth different slant six turbo combo I've tried. The first one was a K-car turbo and blow through carb, followed by the same turbo with EFI, then the EFI system with a much larger turbo. The last combination came to an end when a clogged oil pick-up and high RPM dyno pulls left me with a bit of rod knock. And a teardown also revealed damage to the engine block. See this thread for details.

    I have several members of slantsix.org offer free or cheap parts to get the Dart project back together, and I took them up on an offer of a free engine block and two stock crankshafts. I also bought a used Comp cam and a set of Erson lifters.

    So right now the block and crank are at the machine shop. The block was already bored 0.030" over, so it's getting a little more overbore. Piston options don't have much of a middle ground with slant sixes right now. You can go with basic cast pistons. Or you can go all out with a set of 7.005" H-beam rods (stock is 6.7") and forged pistons intended for something like a Neon SRT4 or 2.2 Turbo, or a set of Wiseco 10:1 pistons. I've opted for the cheap cast pistons here - from what I've seen, they hold up well when hit with a 100-150 hp shot of nitrous or a 10-15 psi boost level. There will also be some attempt at head porting.

    Hopefully the final rear wheel horsepower should be significantly above the 120 hp the previous build put down at 5 psi of boost.
    Attached Files

  • #2
    what will the wall thickness be after overbore?
    Doing it all wrong since 1966

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    • #3
      I haven't had the wall thickness sonic checked, but these motors have a lot of wall thickness. I've heard of them being bored 0.130" over.

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      • #4
        A friend and I did a /6 with 0.060 over with no issues. Tough engines! There should be off-the-shelf forged pistons for these guys but darn if I can remember the application any more.

        Dan
        Last edited by DanStokes; March 5, 2020, 11:58 AM.

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        • #5
          Yeeeeeessssssssssssszzzz

          You and Randal Burns can have a battle of the turbo in-line 6's!!
          Last edited by BBR; March 5, 2020, 02:43 PM.
          Life is short. Be a do'er and not a shoulda done'er.
          1969 Galaxie 500 https://bangshift.com/forum/forum/ba...ild-it-s-alive
          1998 Mustang GT https://bangshift.com/forum/forum/ba...60-and-a-turbo
          1983 Mustang GT 545/552/302/Turbo302/552 http://www.bangshift.com/forum/forum...485-bbr-s-83gt
          1973 F-250 BBF Turbo Truck http://www.bangshift.com/forum/forum...uck-conversion
          1986 Ford Ranger EFI 545/C6 https://bangshift.com/forum/forum/ba...tooth-and-nail

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          • #6
            Originally posted by Matt Cramer View Post
            I haven't had the wall thickness sonic checked, but these motors have a lot of wall thickness. I've heard of them being bored 0.130" over.
            I never realized it was a thing until I went to turbo my 455... this is why it's now 430 ci and sleeved.... but all I know about Mopar is they make a motor that is in crooked ;)
            Doing it all wrong since 1966

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            • #7
              Originally posted by SuperBuickGuy View Post

              I never realized it was a thing until I went to turbo my 455... this is why it's now 430 ci and sleeved.... but all I know about Mopar is they make a motor that is in crooked ;)
              Actually, the engine is straight. It's the car that's on a slope.

              Dan

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              • #8
                Originally posted by DanStokes View Post

                Actually, the engine is straight. It's the car that's on a slope.

                Dan
                so you're saying that Mopar lovers are a half-bubble off-center?
                Doing it all wrong since 1966

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                • #9
                  Patrick & Tammy
                  - Long Haulin' 2008, 2009, 2010, 2011, 2012, 2014...Addicting isn't it...??

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                  • #10
                    Originally posted by SuperBuickGuy View Post

                    so you're saying that Mopar lovers are a half-bubble off-center?
                    Absolutely! And I'm proud to say I'm one of 'em - but I'm a car slut and love 'em all.

                    Dan

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                    • #11
                      Originally posted by SuperBuickGuy View Post

                      so you're saying that Mopar lovers are a half-bubble off-center?
                      I'm trying to build a motor that may have made 110 hp on a good day for performance in a car that will readily accept a small block V8, so that may be understating the case.

                      Today's update - it appears the cheap stock replacement vs money is no object discrepancy is even larger with timing chains. I ordered a Cloyes timing chain from Rock Auto; this picture certainly looked like a decent enough part.

                      Click image for larger version  Name:	C-3022K__ra_p.jpg Views:	0 Size:	65.3 KB ID:	1264652
                      Only here was what I actually found in the box.

                      Click image for larger version  Name:	1583860002_please-not-this-style-cam-sproket_mmthumb.jpg Views:	0 Size:	188.5 KB ID:	1264653
                      If you're thinking this looks a bit fragile, you're right - others in the slant six community have reported problems with the spokes cracking over 4000 RPM. These gears appear to originate from Melling based on their casting number.

                      After looking through Rockauto and trying to talk Summit's tech support into opening up the box on a Comp timing chain to see if they're using the same gear (emailed yesterday, haven't heard back), I went and ordered a Roll-Master double roller chain, made in Australia. They're twice the price of the Comp chain and four times the price of the Cloyes, but the whole goal with this rebuild is going to be buy things once and cry once.
                      Last edited by Matt Cramer; March 10, 2020, 12:58 PM.

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                      • #12
                        Is the top pic an Elgin TC-3022?


                        Life is short. Be a do'er and not a shoulda done'er.
                        1969 Galaxie 500 https://bangshift.com/forum/forum/ba...ild-it-s-alive
                        1998 Mustang GT https://bangshift.com/forum/forum/ba...60-and-a-turbo
                        1983 Mustang GT 545/552/302/Turbo302/552 http://www.bangshift.com/forum/forum...485-bbr-s-83gt
                        1973 F-250 BBF Turbo Truck http://www.bangshift.com/forum/forum...uck-conversion
                        1986 Ford Ranger EFI 545/C6 https://bangshift.com/forum/forum/ba...tooth-and-nail

                        Comment


                        • #13
                          Sure looks the same. The part number also suggests it's the same - Cloyes is C3022K. But there's enough cases of sellers repackaging each other's items and enough cases of sellers who used the photo of what the supplier from five years ago sent them that I can't be certain of what I'd get on that auction. The Roll-Master timing chains are a sure thing - they make their own sprockets and have pretty much established themselves as "the" go to brand if you want a top of the line. They even offer two options - Red Series (overkill) and Gold Series (insanely overkill).

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                          • #14
                            Back from the machine shop.

                            Click image for larger version

Name:	IMG_20200311_1207469001.jpg
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                            • #15
                              Groovy !!

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