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ENGINE BALANCING

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  • ENGINE BALANCING

    Hey guys, Im getting ready to start building my motor for the car. I have some questions about blueprinting and balancing that maybe someone can shed some light on for me (barney style) since I cant find a "keep it simple, stupid" answer online.

    Most parts Im going to order...i.e. pistons, rods, valves.....are going to come blueprinted...I will not have a need to take them to a machine shop and they (if coming from a reputable manufacturer) should already be matching...along with wrist pins and bearings etc etc etc etc.... correct ?!?!?!

    As far as balancing goes, that will pretty much depend on how anal I am with the tolerances I put into the motor and how I have my valvetrain and bottom end put together and tighened up?
    Am I wrong here? Has anyone got any links that I can study, I have gone through books and books and books and just about anything I can find online before I start to build my first motor.
    Who are you to tell me my uninformed opinion is wrong?!?!?

    Expert: He who has made all the mistakes there is to make in a given field.

  • #2
    Take everything to the balancer, including your new rods and pistons.
    This is the entire rotating assembly, everything from the front pully bolt, all the way back to the clutch plate.
    Even the new Wisecos aren't exactly the same weights. My machinist got every rod balanced to within 3/10ths of a gram.
    1987 300ZX Turbo - http://www.z31performance.com/forum/vie ... php?t=3114
    2001 Tiburon Turbo 60-1 270whp/268tq

    No cupholders? Where am I gonna put my beer????

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    • #3
      blueprinting simply means measuring.. it isnt an actual mechanical service.. when someone says they blueprinted their engine, it means that they checked every single measurement before final assembly.

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      • #4
        they basically take a straight edge to the top of the heads to make sure they are perfectly flat.

        then they use a bore dial (i can't remember what its called, its been so long since i used one) to check all your cylinders.

        then they check your mains as well.

        nothing special except to tell you that your engine is in spec.

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        • #5
          84z31 wrote: they basically take a straight edge to the top of the heads to make sure they are perfectly flat.

          then they use a bore dial (i can't remember what its called, its been so long since i used one) to check all your cylinders.

          then they check your mains as well.

          nothing special except to tell you that your engine is in spec.
          Thats exactly what I said...only I think I over explained it.
          I did that today with my wife (overexplained) and we argued about how I was going to hang our bikes in the garage...argued for 5 minutes and came to the conclusion I had the previous hour.

          I will get everything together then....I read up on some of it here
          ENGINE BALANCING LINK
          and I just really wanted to do it myself. I have access to everything I need except the experience of actually doing the work.....well, scratch that if stuff requires machining. Im not going to take a dremel to some rods to cut weight. I can check tolerances though.

          In the end, as much as I want to do it....I know you guys are right and I should just take it to someone
          Who are you to tell me my uninformed opinion is wrong?!?!?

          Expert: He who has made all the mistakes there is to make in a given field.

          Comment


          • #6
            There's more to balancing than just getting the parts to an equal weight. You have to measure both ends of the rods, then rotate the crank on a machine that tells you where to grind or weld it...........

            It costs thousands just to buy the tools to properly balance a motor.

            Don't worry about it and jsut take it to someone who knows.
            1987 300ZX Turbo - http://www.z31performance.com/forum/vie ... php?t=3114
            2001 Tiburon Turbo 60-1 270whp/268tq

            No cupholders? Where am I gonna put my beer????

            Comment


            • #7
              yes balancing should be done by the machine shop. You balance your crank to the rods you buy. The rods should come within a gram of each other but that doesnt mean the counter weights on the crank are even remotley close to the proper weight to match the new rod. You should see my crank counter balancers (fillets I think) after I got it balanced with new rods. They pulled A LOT of weight out of the fillets of the crank to properly balance it. Drilled Three LARGE holes x amount deep in each fillet.

              Also each engine has a different formula for balencing it. inline fours are different that flat 4's and v6's I hear are different than every other engine. Either way, Any time an engine is to be assembled, it should be balanced BY A MACHINE SHOP

              And yes, blueprinting is just writing down as much info about clearances as possible when assembling. You can shift your tolerances to the loose side for slightly more power (but more play and wear) or to the tight side for long-gevity sp?
              85 Z31 6.0 LSX turbo 766whp/792wtq
              04 GTO, LS6, big cam, porting, N20... underway for summertime daily driver.

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              • #8
                Yea, my balancer had to grind a LOT off the crank. He also had to do quite a bit of grinding off the TT rods to match them up.
                The VG isn't balanced very well from the factory. Most newer motors are a lot more balanced than the VG. When I had my 2.0 Hyundai motor balanced, the crank didn't need to be touched at all.
                1987 300ZX Turbo - http://www.z31performance.com/forum/vie ... php?t=3114
                2001 Tiburon Turbo 60-1 270whp/268tq

                No cupholders? Where am I gonna put my beer????

                Comment


                • #9
                  Evil Z31 wrote: Most newer motors are a lot more balanced than the VG. When I had my 2.0 Hyundai motor balanced, the crank didn't need to be touched at all.

                  Is that 2.0 Hyundai engine the 4G63? If so, doesn't that engine have balance shafts? It's funny, I was informed by a Mitsubishi Technician that you can remove the balance shafts in a 4G63 and it will just idle like a Saturn!!! So here sits my Talon without the balance shafts, 3 years later with no
                  problems, and it idles smoother than a Saturn.

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                  • #10
                    No, its a g4cp, "Beta". It's the second motor designed by them in the mid 90's. It doesn't have balance shafts.
                    1987 300ZX Turbo - http://www.z31performance.com/forum/vie ... php?t=3114
                    2001 Tiburon Turbo 60-1 270whp/268tq

                    No cupholders? Where am I gonna put my beer????

                    Comment


                    • #11
                      Evil Z31 wrote: Yea, my balancer had to grind a LOT off the crank. He also had to do quite a bit of grinding off the TT rods to match them up.
                      The VG isn't balanced very well from the factory. Most newer motors are a lot more balanced than the VG. When I had my 2.0 Hyundai motor balanced, the crank didn't need to be touched at all.
                      her is my question about how well the VG's are balanced: my understanding of a well balanced engine is that it A: idles and runs more smoothly than a poorly balanced motor, and B: is more reliable because balanced motors don't vibrate and vibrations are engine killers. With that in mind why is it that the VG's are incredibly reliable motors and are widely regarded by the nissan enthusiasts to be one of the most reliable V6's nissan ever made?
                      Funny stories!

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                      • #12
                        Having a well balanced motor allows you to rev higher and cause less stress and vibrations when doing so. A stock VG isn't a high reving motor.
                        1987 300ZX Turbo - http://www.z31performance.com/forum/vie ... php?t=3114
                        2001 Tiburon Turbo 60-1 270whp/268tq

                        No cupholders? Where am I gonna put my beer????

                        Comment


                        • #13
                          ^ But what makes you believe VGs aren't well ballanced?
                          imagination is a virtue

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                          • #14
                            craZed wrote: ^ But what makes you believe VGs aren't well ballanced?
                            When you put in rods and pistons much lighter than stock, then it will be out of balance quite a bit.
                            Drive


                            1975 Datsun 280Z
                            1988 300ZX (NAtoT soon)
                            2006 Kawasaki ZX6R

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                            • #15
                              FreeLanceBum wrote: When you put in rods and pistons much lighter than stock, then it will be out of balance quite a bit.
                              so you're saying that it is well balanced from the factory, but when you put in aftermarket parts and don't have them balanced not so much.... isn't that true of any engine?
                              Funny stories!

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