How Big can a 5.2 get?

Discussion in 'Magnum Engine Swaps' started by Dusterfreak, Nov 25, 2017.

  1. Dusterfreak

    Dusterfreak Well-Known Member

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    What size can a 5.2 be bored over? I know alot of older 318`s been bored for 340 pistons but how about magnums? I just got a 5.2 thats been sitting and its got rust in the cylinders so an overbore is a must...
     
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    • toolmanmike

      toolmanmike FABO Staff Staff Member FABO Gold Member

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      I
      I think I remember seeing about .040 is the max. Anything more than about .030, I would have it sconic checked.
       
    • Lelo Dart

      Lelo Dart *

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      Have heard .030 but I went .020. I would have gone .010 but I couldn't get Magnum pistons in that size.
       
    • RustyRatRod

      RustyRatRod Just another dumbass. Technical Editor

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      I have conveniently forgotten the name but there's a well known Mopar engine shop that builds 4" plus bore 318s. Been doin it probably 30 years. Moper will remember it if he sees this.
       
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      • RustyRatRod

        RustyRatRod Just another dumbass. Technical Editor

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        Hensley Motorsports. Dammit I nearbout burnt my brain up thinkin about that.

        They've been buildin big inch 318s for a while.
         
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        • pishta

          pishta I know I'm right....

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          360 bores are a +.090 but 340 bores, thats a +.130, or over a 1/4 inch diameter overbore! If thin is in, they are Flynn! Now 'big inch' is more plausable with > 4.15 stroke LA cranks available now.
           
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          • Tooljunkie

            Tooljunkie King of cobble/master of the broken bolt FABO Gold Member

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            There were some truck “premium” blocks that could be bored over.
             
          • 67Dart273

            67Dart273 Well-Known Member

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            Let's not forget you can stroke 'em or even just start with a 5.9 and go from there!!
             
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            • rumblefish360

              rumblefish360 so close yet so far away

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              The 318 from Hennsely gets sonic checked for a 4.00 bore.

              The 318’s cylinderwalls are only so thick. How far it goes needs a sonic check to know for sure.

              I suggest not think it can go to a 4.04/340 bore.
               
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              • Dusterfreak

                Dusterfreak Well-Known Member

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                I was looking for a 5.9 but those are rare here in finland, pickn pulls were asking 1500€, its almost 1800$ :D
                I was thinking about stroking, but that includes 0.030 overbore also and a 2000$ plus freight plus taxes so ill be in 3000$ then...
                 
              • RustyRatRod

                RustyRatRod Just another dumbass. Technical Editor

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                Well of course they do. I kinda figure some things just go without sayin. lol
                 
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                • RustyRatRod

                  RustyRatRod Just another dumbass. Technical Editor

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                  3K is pretty cheap for an engine.
                   
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                  • rumblefish360

                    rumblefish360 so close yet so far away

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                  • 67Dart273

                    67Dart273 Well-Known Member

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                    Oh, FINLAND I didn't notice your location. I'm in "the sticks" of the N end of Idaho state, and can sometimes "bitch" about the lack of used speed parts, etc. But you guys must have it ROUGH!!!
                     
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                    • Dusterfreak

                      Dusterfreak Well-Known Member

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                      That would only be the shortblock.. add heads, cam,valvetrain and intake...
                       
                    • famous bob

                      famous bob mopar misfit

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                      .030 , is .005 over an 1/8" -----------------------1/4" is .0250
                       
                    • RustyRatRod

                      RustyRatRod Just another dumbass. Technical Editor

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                      3K is pretty cheap for a short block, too.
                       
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                      • RustyRatRod

                        RustyRatRod Just another dumbass. Technical Editor

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                        There. I fixed your decimals. lol
                         
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                        • toolmanmike

                          toolmanmike FABO Staff Staff Member FABO Gold Member

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                          :thumbsup:
                          A little zero makes a huge difference.
                           
                        • pishta

                          pishta I know I'm right....

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                          you wanna go +.130 (340 bore out of a 318) I was thinking radii to diameter..my bad.
                           
                        • Lelo Dart

                          Lelo Dart *

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                          390 cubes with a 4" stroke
                           
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                          • Dusterfreak

                            Dusterfreak Well-Known Member

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                            Now I have a plan... 0.030 over with KB 167-30 pistons, eq heads and air gap :)... Thats if water hasnt ruined two cylinders.
                             
                          • YY1

                            YY1 Well-Known Member

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                            .040 with 4 inch is 392 IIRC and I think can go larger bore.

                            Has the OP tried honing?
                             
                          • famous bob

                            famous bob mopar misfit

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                            thot that`s what I said ! my bad .
                             
                          • AJ/FormS

                            AJ/FormS 367 FormS clone 3.09-1.92-1.40-1.09-.78od 3.55s

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                            What's the application?