Engine build help please

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  • LM1M
    Senior Member
    • May 2007
    • 384

    #1

    Engine build help please

    Limited Late model engine build advice needed; 350 SBC steel block/steel heads with flat top pistons, 3.48 crank, 10.5 compression, and 4 Bbl carb. 5.7 or 6 inch rods, and why?

    Thanks in advance.
  • Basecircle
    Member
    • Dec 2016
    • 82

    #2
    6", because it has less working angle as the crank rotates. Puts less pressure against the cylinder walls by being more straight up and down as it works. Also puts the pin higher in the piston which has benefits. We've run even longer than 6, but it's not as common so the price of pistons goes up considerably and there's not near as many options.

    Comment

    • LM1M
      Senior Member
      • May 2007
      • 384

      #3
      Thanks Basecircle; rules state 5.7 or 6" rods only.

      Comment

      • fastford
        Senior Member
        • Dec 2008
        • 4059

        #4
        the 6in rods also increases piston dwell , which benefits higher rpm engines , how ever a 5.7 will create more low rpm torque , i have seen both win races , i prefer the 6in on the chevy,s because most tracks are 3/8ths or longer that we race on. My ford all steel engines are 302 based 355cid with 5.4 rods and 1in CH pistons and they pull like a mule off the corner , but you have to coat the piston skirts well , which i would suggest doing on any piston.

        Comment

        • LM1
          Senior Member
          • Jul 2015
          • 328

          #5
          This will be in a low RPM motor, there is a 6500 RPM rule

          Comment

          • Brian Gray
            Senior Member
            • Feb 2012
            • 1102

            #6
            Your going to want it to pull harder . A 5.7 rod will help get some grunt out of it. It will also save you some weight to help it rev quicker. IMO the longer rod only benefits you if your going to turn the rpm up. My rule is below 7000 shorter rod .
            Shocks by BGR army

            Comment

            • old17ford
              Senior Member
              • Jan 2010
              • 306

              #7
              Fastford how much do you turn your motor with this set up ?

              Comment

              • fastford
                Senior Member
                • Dec 2008
                • 4059

                #8
                rarely over 7500, with the correct cam , it will pull good to 7000 , but with flat tappets thats about it for usable power.

                Comment

                • RCJ
                  Senior Member
                  • Nov 2007
                  • 509

                  #9
                  Rod length plays a bigger role on engines that are restricted. I know drag racers that believe all the rod does is hook the piston to the crank.I always go with a longer rod because I want a lite piston.

                  Comment

                  • hipower17
                    Senior Member
                    • Dec 2007
                    • 643

                    #10
                    what tracks are runing this?

                    Comment

                    • LM1M
                      Senior Member
                      • May 2007
                      • 384

                      #11
                      USRA Late models in midwest

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