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Can a 410 FE(4.05" x 3.98") be internally balanced reasonably?

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  • Can a 410 FE(4.05" x 3.98") be internally balanced reasonably?

    Hi. New guy here! Thanks for having me. I am totally new to FE engines & T-Birds. It seems that a 360/390 block stroked with a 3.98" crank is a very cost effective & modest way of getting more cubes. I do understand that more stroke in the 390 block is available, but probably choose not to because of longevity. I have found Scat Cast & Eagle Forged cranks. Can either of these be internally balanced at a reasonable cost? I know many things can be done by Cubic Dollars, but I don't want to spend them. "Bobweight" is probably at the cusp of my understanding, a "recipe" would be wonderful. I believe sometimes it's easier to do than to have to understand it till you need to. Sorry for a tough first question. Thanks, Tim

  • #2
    This is only a tough question if you don't have knowledge pertaining to 'engine balancing'. All FE engines can and should be internally balanced. Understand though, you can't simply balance a crankshaft by itself. I bring my crankshaft, flexplate, damper pulley, and a complete piston & rod assembly sample (with rings rod, wrist pin and keepers, bearings, cap and bolts) to my crankshaft balancer.

    The factory uses the same weight components so they can get away with balancing just the crankshaft. If you change pistons, rings, etc., your new weight will be different and probably heavier than OEM. The cost for crankshaft balance is about $125. Don't think you can purchase a crankshaft or the other components and expect them to be in balance. It never works that way.

    Bob weights are used to simulate the weight of your piston assemblies. Mallory Metal is welded into the crankshaft throws if your new pistons are a lot heavier than OEM. So, the heavier the pistons, the more mass is required in the crankshaft counterweights. - Dave
    My latest project:
    CLICK HERE to see my custom hydraulic roller 390 FE build.

    "We've got to pause and ask ourselves: How much clean air do we need?"
    --Lee Iacocca

    From: Royal Oak, Michigan

    Comment


    • #3
      Dave . . . You know your stuff !!!

      The thing I like about the 410 is it's almost square (4" X 4")
      That's usually a good thing.
      I saw a 59 @ the last good guys show with one. Sounded good.
      He said it runs like a raped ape.
      There's another local that has a 428 stroker (462 I think) in a 1950
      Ford Coupe. Now THAT would be too much.

      How've you been

      John Byers
      1960 Convertible (Orig owner)
      sigpic

      Comment


      • #4
        All V8 crankshafts are much more complicated to balance than an in-line (4-cyl or 6-cyl or opposing cylinder or radial) design because V8 cylinders are offset by 90 degrees. In a sense, in-line engines should run smoother because there is no offset angle between cylinders.

        There is no magic formula in balancing a V8 crankshaft. Each piston assembly's 'rotating' weight and the 'linear-motion' weights must be taken into account, then they add a couple grams for the weight of oil in the rings when calculating bobweights. Then, they spin the crankshaft with the bobweights attached. A dynamic balance machine will show exactly where and how much the imbalance is on the 'post end' and on the 'flange end' of the crankshaft.

        Engine plants make 1,000 of the same size engine every day. They use the same components which closely weigh the same in every engine. Therefore, they only need to take an average sample of the same production engines to determine a bobweight value. Yes, there are tolerances and sometimes they 'stack' which is why some engines are real 'sweethearts' right off the showroom floor. Other tolerances can produce 'lemons' but for the vast majority, production engines are good. So, Ford balances their crankshafts the same for all the same engines. Crate engines are popular because they are made on the assembly line which makes them inexpensive.

        Now we come to the part where your block is bored, larger pistons and rings are purchased and maybe some 'custom' components are used including perhaps different rods and bolts & nuts which affect crankshaft balance. There is a difference in wrist pin weights between manufacturers, too.

        This is the part I love when building an engine. When you bring your rotating parts to a crankshaft balancer and your new parts are not heavier than the counterweights, that balance machine will produce a crankshaft that is FAR superior to production-line balancing. But wait. A single piston that weighs differently will prevent a smooth engine. Before we balance, are all the pistons the same weight? Are all the connecting rods the same weight? Each end of the con rod must be weighed separately because one end is rotary while the other end is linear. When put together, are the piston assemblies (piston, wrist pin, snap rings, connecting rod with end cap, bearings, bolts and nuts) the same weight? If so, I give ONE piston assembly to the balancer as a sample for the bobweight mass before spinning the crank in the balance machine. I also include the flex plate and damper pulley so that they are part of the total balance.

        If the balance machine indicates the imbalance is too far out, that means the counterweights need more mass. They drill a big hole in the throw on the light end, and weld-in a slug of Mallory Metal (1-1/2 times the weight of lead). Then they spin the crank again and repeat the process. This is custom work that takes time, that Ford doesn't have if they want to keep costs down. Weighing all the components is easy work but it takes time. If you do your own work the end result is very rewarding. - Dave
        My latest project:
        CLICK HERE to see my custom hydraulic roller 390 FE build.

        "We've got to pause and ask ourselves: How much clean air do we need?"
        --Lee Iacocca

        From: Royal Oak, Michigan

        Comment


        • #5
          A common hop up with the Chevy 350 is to run a 400 crank.
          Comes out to a 383. Lotta torque with that combo. It is similar in that a 400
          is also externally balanced, so you need to run the weighted 400 flywheel (or flex plate)
          I think balancing was tricky with those.
          The block also needs to be notched for clearance. That was the old way.
          Now crankshafts & pistons are common for that combo. Chevrolet even sells a Performance crate version
          435 HP @ 5600 rpm & 445 Ft Lbs of Tq @ 4600

          I know with the Harley's too, balancing the flywheels (crankshaft) is a true art
          Two pistons going up and down (almost) at the same time.
          John Byers
          1960 Convertible (Orig owner)
          sigpic

          Comment


          • #6
            [QUOTE=alnukem;n234875 Can either of these be internally balanced at a reasonable cost? Tim[/QUOTE]

            The true and accurate answer to this question cannot be answered here, on this forum (or any other), but rather can/will be concluded at the time of the revolving balancing undertaking, by the hopefully knowledgeable individual contracted and thru communication for such, and as "reasonable" is of course a relative term, a choice may be presented.

            As originally delivered from the Ford Motor Co. the 410 and 428 cu.in., unlike other FE engines due to the additional stroke value, carried an external imbalance sum on the flex-plate or flywheel, and the 428 SCJ also carried and additional sum on the crankshaft snout. What efforts (read costs) may be required to achieve "balance" whether "internal" or "neutral" or with an external sum with the production inconsistencies the current "import" crankshafts is unknown until attempted.

            And, so what is your concern if the crankshaft should carry a reasonable (perhaps O.E.) sum of external counter weight? It worked fine for Ford Motor Co., and has for many a ":H*ll-Raiser" punishing their 428CJ' & SCJ's?

            Scott.

            Comment


            • #7
              Scott raises good points. External weight is usually added to the flex plate (on certain engines) and the damper pulley is certainly a factor as well which is why the flex plate and damper pulley need to be included when submitting the crankshaft for an accurate balance.
              More modern 351W engines use a different flex plate external weight from the 5.0. I'm sure there are other engines that use external weight as well. But, that doesn't mean the crankshaft cannot be internally balanced. It only means, this method is much easier and cheaper to do. The only constriction is, the flex plate is only on the flange end of a crank.

              Scott is right. Who cares where weight is added as long as the rotating assembly is in balance.

              When Ford foundries deliver rough crankshaft castings to the engine plant, they commonly include sand holes (small voids) in the castings. Instead of throwing those crankshafts away, Ford came up with a brilliant way of saving them... Ford spins the rough casting to find where the imbalance is. Then, they drill center holes in the 'MASS CENTER' of the ends, not the geometric center. Now, the center holes are closer to the heavy side and machining can continue before 'finish grinding'. This has saved Ford countless money in scrap costs..

              Dearborn Engine Plant balances their crankshafts to 5-gram/centimeters. This is a number that was impossible to achieve when we were balancing FE engines because our controls were relay, not solid state. So, I urge every overhaul to include crankshaft balancing. You will be amazed with how smooth your engine will be. - Dave
              My latest project:
              CLICK HERE to see my custom hydraulic roller 390 FE build.

              "We've got to pause and ask ourselves: How much clean air do we need?"
              --Lee Iacocca

              From: Royal Oak, Michigan

              Comment


              • #8
                Thanks guys! I do understand that there are a lot of variables......Forged stuff is heavier than cast, hyper pistons probably fall in between. I did find Jim Dove's site & he said it only takes 1 piece of Mallory Metal to do a internal balance on a 410 or 428. I understand that this is a generalization. I do have a line on some 390's & a couple of 428's. I really did not want to build a "barn-burner" just something with some torque & probably a Hyd Roller. We will see, I am finishing some projects this summer. I wish i understood FE engines 40 years ago with my 68 Mustang. It ended up as a 351W station wagon motor with the 69 351W heads. I think I would have been happier with a 352FE. Thanks again.

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