3:54 vs 4:10 with a low deck 499

Transmission and Drivetrain Tech

  1. forced 340

    forced 340 Well-Known Member

    Messages:
    734
    Likes Received:
    42
    Joined:
    Aug 29, 2011
    Location:
    michigan
    Local Time:
    1:47 AM
    I am building a almost 12:1 499 low deck for my 70 swinger. it will have TF 270's, solid flat tappet (for now), indy max wedge single plane, 1050ish dommy, rmvb 727 with lots of a&a goodies, lupo 9.5'' convertor (i'll be sending it in when i decide on gear ratio), 325/50-15 drag radial ''r''. my question is, has anyone run a similar set up with a 3:54? should i run the 4:10? i dont do a lot of freeway driving, but would like to. i am trying to keep the rpm's down while cruising too. i currently have a very nice, braced 8.75 with a 4:10 in the car now, but i have a dana ill be narrowing with the 3:54 factory gears. let me know what you guys think, and thanks for the advice!
     
    • Like Like x 1
    • Garrett Ellison

      Garrett Ellison Amateur driver on public roadway, do not imitate.. FABO Gold Member

      Messages:
      3,362
      Likes Received:
      2667
      Joined:
      Jan 1, 2018
      Location:
      Southwest VA
      Local Time:
      2:47 AM
      I like it! With the 28.3 inch tire diameter and accounting for tire growth at highway speed your looking at between 2400-2500 crank rpm. It sounds like a whole lot of fun to me, should be able to blow the tires off at will at almost any speed...
       
      • Like Like x 1
      • Ottmundr

        Ottmundr 68 Fastback

        Messages:
        7,622
        Likes Received:
        11778
        Joined:
        Oct 5, 2012
        Location:
        Sonoma
        Local Time:
        11:47 PM
        You will have lower piston speeds with the 3.54 gearing, especially with the (?)4"(?) Stroke you will be running. I think that is something you may want to consider.

        You are going to have more than enough torque with that B block in an A body that getting off the line won't be a problem.

        Personally, I would go with a 470 build. It gives lower piston speeds, and greater compression height on the pistons which hypothetically should get you a longer engine life. The shorter stroke allows higher rpm's and you can take advantage of the 4.10 gearing just a little better.

        Double check all of this with a calculator. Talk to @AJ/FormS about gearing and your trans ratios and tire sizes et cetera.
         
        • Like Like x 2
        • RustyRatRod

          RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

          Messages:
          70,700
          Likes Received:
          45570
          Joined:
          Jun 7, 2010
          Location:
          Georgia
          Local Time:
          2:47 AM
          That combo would pull a 2.94 gear.
           
          • Agree Agree x 2
          • Like Like x 1
          • Ottmundr

            Ottmundr 68 Fastback

            Messages:
            7,622
            Likes Received:
            11778
            Joined:
            Oct 5, 2012
            Location:
            Sonoma
            Local Time:
            11:47 PM
            Fixed it for you.:poke:
             
            • Like Like x 2
            • Agree Agree x 1
            • RustyRatRod

              RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

              Messages:
              70,700
              Likes Received:
              45570
              Joined:
              Jun 7, 2010
              Location:
              Georgia
              Local Time:
              2:47 AM
              ha!
               
              • Like Like x 2
              • Garrett Ellison

                Garrett Ellison Amateur driver on public roadway, do not imitate.. FABO Gold Member

                Messages:
                3,362
                Likes Received:
                2667
                Joined:
                Jan 1, 2018
                Location:
                Southwest VA
                Local Time:
                2:47 AM
                I’d be willing to bet it’d pull a Winnebago with 2.94 gears while towing your A body behind it...
                 
                • Like Like x 1
                • Ottmundr

                  Ottmundr 68 Fastback

                  Messages:
                  7,622
                  Likes Received:
                  11778
                  Joined:
                  Oct 5, 2012
                  Location:
                  Sonoma
                  Local Time:
                  11:47 PM
                  Just got home, here's a book you may just want to add to your library. Really, just get the book, it's only twenty bucks.

                  https://www.amazon.com/dp/1934709476/?tag=fabo03-20

                  I don't want to get anyone in trouble for copyright violations so I am not going to take pics of the pages and post them up. I'll type in the formulas though.

                  Mean Piston Speed (in feet per minute) = stroke * RPM / 6
                  example ;
                  3 inch stroke, max rpm of 6,000
                  PS(fpm)=3*6000/6=3000fpm

                  Max Piston Speed = MPS
                  fpm = feet per minute
                  MPS(fpm) = (stroke * pi / 12) * RPM
                  using the same engine above;
                  MPS(fpm)=(3.000*3.14/12)*6000
                  MPS(fpm)=4,710

                  Piston Acceleration
                  1g=32fps^2

                  Max Acceleration = MA

                  MA = (RPM^2 * stroke / 2,189) * 1.33
                  same engine as above
                  MA=(6000^2*3/2189)*1.33
                  MA=65,767ft/sec^2
                  that's about 2,055 gravities! multiply that by the mass of the piston, and you can calculate how much weight is being placed on your rods, pins and pistons.

                  Now same thing with a 3.915" stroke for a 470 cid B block
                  MA=85,632ft/sec^2
                  2,676 gravities

                  Now same thing with a 4.150" stroke for a 499 cid B block
                  MA=90,977ft/sec^2
                  2,843 gravities

                  That's a difference of 167 gravities. How much do you REALLY benefit with that increased stroke. After having gone over these formulas I decided to NOT stroke my 360 to a 4" arm. The cost:benefit ratio just isn't there. I'll put the money in better heads, rev it higher and have a longer lived engine. Even with my 4.10 gearing

                  Calculating RPM limits

                  RPM = (desired piston speed * 6) / stroke

                  You need to contact your piston manufacturer to find out the safe limits on piston speed for your pistons... cast/hypereutectic/forged.
                  Keep in mind oil control with high piston speeds...
                   
                  • Like Like x 1
                  • Thanks! Thanks! x 1
                  • Agree Agree x 1
                  • Ottmundr

                    Ottmundr 68 Fastback

                    Messages:
                    7,622
                    Likes Received:
                    11778
                    Joined:
                    Oct 5, 2012
                    Location:
                    Sonoma
                    Local Time:
                    11:47 PM
                    Also, check out the compression height differences between the 470 and 500 CID engines.

                    Stroker Kits-440 Source

                    470 = 1.480 compression height, rod length is 6.535"
                    vs
                    500 = 1.222 compression height, rod length is 6.760"

                    Do you need the better rod ratio enough?

                    That's a 0.258" difference, just a hair over a quarter inch. Is the bottom ring unsupported? What kind of piston rock will you get? Do you need extra long skirts to help make up? What kind of balancing needs done? (The balancing is probably a wash, but that's just a guess on my part).
                     
                    • Like Like x 2
                    • Agree Agree x 1
                    • oldkimmer

                      oldkimmer FABO Gold Member FABO Gold Member

                      Messages:
                      18,847
                      Likes Received:
                      6198
                      Joined:
                      Nov 11, 2006
                      Location:
                      Kindersley, Saskatchewan,
                      Local Time:
                      1:47 AM
                      Those big ports will want more gear. Kim
                       
                      • Like Like x 1
                      • Agree Agree x 1
                      • silversedan

                        silversedan Well-Known Member

                        Messages:
                        76
                        Likes Received:
                        67
                        Joined:
                        Oct 8, 2016
                        Location:
                        Edgar, Wi.
                        Local Time:
                        1:47 AM
                        in an a-body I'd do a 470 like suggested with the 240 tf heads if it 's a street car, a friend built that same motor with a 550 hyd cam 240 heads 11.0 comp, in a 63 belvedere with 3.91 gears, he ran it at the track 11.07 with lots of tuning left. single four bbl. 800 avs. pretty darn fast with no tuning.
                         
                        • Like Like x 2
                        • Kern Dog

                          Kern Dog FABO Gold Member FABO Gold Member

                          Messages:
                          5,600
                          Likes Received:
                          9617
                          Joined:
                          May 23, 2010
                          Location:
                          Granite bay CA
                          Local Time:
                          11:47 PM
                          I had 4.10s in my Charger for several years. It was absolutely snappy even though the car weighed almost 4000 lbs. It got maybe 5 mpg around town.
                          Freeway? I didn't do much freeway driving. 3800 rpms at 70 wasn't very much fun!
                           
                          • Like Like x 2
                          • 33IMP

                            33IMP Well-Known Member

                            Messages:
                            851
                            Likes Received:
                            864
                            Joined:
                            Jul 3, 2020
                            Location:
                            Taxifornia, soon 2b arizona
                            Local Time:
                            11:47 PM
                            My guess is.... It will be no quicker at the track with the 4.10s, and a lot less comfy on the street. I would absolutely use the 3.54s, and the dana is a good idea.
                            Edit: quote" I'm trying to keep the rpms down while cruising too" Dr Diff now has 3.23 gears for a dana (new!). I think your engine would pull those too, and they are an excellent compromise gear (as is a 3.54.).
                             
                            Last edited: Aug 13, 2020
                            • Like Like x 1
                            • Agree Agree x 1
                            • Ottmundr

                              Ottmundr 68 Fastback

                              Messages:
                              7,622
                              Likes Received:
                              11778
                              Joined:
                              Oct 5, 2012
                              Location:
                              Sonoma
                              Local Time:
                              11:47 PM
                              Yeah. I am somewhere around 4k at 75mph. It REALLY sucks the gas down, I get around 11mpg, and that's with my tired old 318. My commute went from 13 miles each way to 22 miles each way. No, it's NOT possible to drive slower. Snappy here too, and my compression ranges between 100 and 150. :eek:
                               
                              • Like Like x 1
                              • forced 340

                                forced 340 Well-Known Member

                                Messages:
                                734
                                Likes Received:
                                42
                                Joined:
                                Aug 29, 2011
                                Location:
                                michigan
                                Local Time:
                                1:47 AM
                                wow!! thanks for all the great replies guys! this is great! i am really leaning toward the 3:54.
                                 
                                • Like Like x 1
                                1. This site uses cookies to help personalize content, tailor your experience and to keep you logged in if you register.
                                  By continuing to use this site, you are consenting to our use of cookies.