Announcement

Collapse
No announcement yet.

Operating RPMS?

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Operating RPMS?

    What are normal safe on the engine operating RPM's on the Stude 259?

    My Champ 259 has a different size piston in every hole so I red line it at 2,000 RPM because I'm sure there isn't a lot of balance inside that block and 2,000 will get me into OD.

    However as the Speedster comes together, I expect the 259 in it will be a lot more trustworthy.

  • #2
    I've been building motors for years.....And do not understand your comment about different size pistons in every hole....

    Comment


    • #3
      2000rpm won't even get you down the street..!

      You valve springs will give up way before anything else bad happens. I doubt you'll get much past 5000rpm before the springs stop controling the springs and the engine just won't go any more rpm.

      My ol 259 with old stock springs will choke itself to about 5300rpm before it gives up.
      With new springs, they might take you to 5500/5600rpm....same thing, everything will be just fine at that rpm.

      The crank, rods, wrist pins, pistons, valves....are all plenty strong, somewhat over built for what the engine actually does. The weak point is the springs.

      Mike

      Comment


      • #4
        Were the 259,s internally or externally balanced?

        Comment


        • #5
          Don't know the history on the Champ but based on the body when I got it most of it's life was in a gravel pit or on a construction site. When I pulled the heads, oversize stamps on the pistons looked like quick picks for the lotto. I doubt if balance was in the vocabulary of the corner garage who'd been there before. The engine ran before I opened it. It ran much better and cooler without all the foundry sand in the water jacket and with the valves ground.

          Instead of investing in that engine, since my intent was parades and such rather than drag racing, I replaced rear main seals and freeze plugs and closed it up. We treat it gently and 2000 in OD buys me 50 MPH... plenty for what I think is under the hood.

          I'd plan to drive the Speedster just a bit more aggressively.

          Comment


          • #6
            Wow...I believe you have one of the best examples of a "CASO" overhaul yet! It would be interesting to know the piston sizes by cylinder. Wonder if it affects the exhaust note? You probably have more vibration on that thing than my V-Twin motorcycle.
            John Clary
            Greer, SC

            SDC member since 1975

            Comment


            • #7
              Sorry I didn't take notes. At that point I just covered my eyes and crossed myself! No noticeable vibration until 2200 and I think that is a rear tire issue.

              Comment


              • #8
                Those stamped sizes you found on the block next to each cylinder represent the finished size of each cylinder. The assembler would select an appropriately sized piston for each hole to maintain exact clearance. The difference is only .0005" to .001" usually. And after a few thousand miles of operation those numbers no longer have any real meaning.
                Restorations by Skip Towne

                Comment


                • #9
                  Dwain, others -

                  NOT...necessarily...!

                  I opened up my 23,000 mile old 259 the other day (documented, never been apart). #1 piston has a 35 stamped on the surface. After a measurement OR two...of all of the cylinders...turned up that ALL cylinders are the same size (3.56")...with no ridge to confuse things.

                  While Dwains comment is normally a correct one, my 259 has prooven that it's NOT always the case.
                  ONLY an actual measurement will tell you what the actual diameters are.

                  Mike

                  Comment


                  • #10
                    If you think the vibration is tires, why blame the engine? Put round tires on it and take it for a drive. Had you not opened it up and discovered a possible problem and had good tires, you may have just driven it normally and never knew. Like was stated in an earlier post, the top end will limit your RPM's. If after driving with good tires there is an engine vibration, you will know what your limit is. You don't need to drive like John Force, but you don't need to have turtles passing you either.
                    sigpic1966 Daytona (The First One)
                    1950 Champion Convertible
                    1950 Champion 4Dr
                    1955 President 2 Dr Hardtop
                    1957 Thunderbird

                    Comment


                    • #11
                      I am not a "numbers" person by any means. I know some of you are. I have known some that have such a knack and memory for numbers, that you can give them a Studebaker part number, and they will tell you what year it's for. What I do recall is that when I rebuilt the 259 in my Lark, it had over 80,000 miles showing on a broken speedometer. The engine had no significant wear ridge (using the old "fingernail" test), and after a good honing, required no "reaming" or boring. The only thing I recall is that it was withing acceptable "tolerances" for using standard pistons.

                      I suppose, for the most picky and scientific minded number attentive types, there was probably a measurable variation of cylinder diameter. As a result, I conclude that the difference results in a corresponding "ring-gap" variation in the piston grooves from one cylinder to another. In that case...you could have different cylinder diameters, and uniform diameter pistons. Heck, it has been so long, I don't recall what the plus or minus tolerances are, or what manual I resourced to get the info. Some of you guys that are into building performance and racing engines probably have the figures dancing in your fertile brains!
                      John Clary
                      Greer, SC

                      SDC member since 1975

                      Comment


                      • #12
                        I'm remembering the numbers stamped on the pistons ranged from no notation to several in the .025 to .035 range and at least one North of .050! As my intent for the Champ was a low cost rebuild to learn the anomalies of Studebakers and it has the same drive train as my Speedster and no title low mileage '63 in storage driving it as is made the most sense. Total investment including purchase, paint and mechanical was under $5,000. Tires although 12 years old are matched with good tread and no visible cracking or rot.... another reason to keep the speed down. Did attempt to swap the Speedster tires/wheels on to the Champ and discovered they are not 5 on 4 1/2".

                        Back to the original question phrased a bit differently... Is it safe to assume that 2,500 to 3,000 RPM is a normal comfortable top highway driving range for the 259 in the Speedster?

                        Comment


                        • #13
                          Originally posted by mmagic View Post
                          Back to the original question phrased a bit differently... Is it safe to assume that 2,500 to 3,000 RPM is a normal comfortable top highway driving range for the 259 in the Speedster?
                          Yes, it will live forever at those RPMs. And with the 3.54 it probably has, and 205/75 tires, 2500-3000 RPM will move the car at about 57-69 MPH. The Stude V8 is versatile, and will do whatever the job calls for on either end of the RPM spectrum. You ain't gonna hurt it lumbering along at 1500-2000, nor at 2500-3000, nor at 3000-4000. But generally speaking, the more piston travel per mile, the fewer miles between rebuilds.

                          Mine live most of their cruising RPMs at 2000-2300 here on the east coast, and 2300-2500 when I lived in the southwest, and are usually upshifted at 2500-3500. I am also a firm believer in occasionally taking her up to around 4000 just to keep the carbon blew out.

                          Comment


                          • #14
                            I limit my 289 2 bl. auto GThawk to 2100 rpm. That get's me to bout 60. Once I had it up to 85 for a split second or 2. 55Pres 259 DG 250 rear? No tach. 65MPH tops if I am driving fast. Or if I'm driving slow I leave bout 7 minutes earlier per 63 mile trip destination. I don't try to keep up with the crazies out there. jimmijim
                            sigpicAnything worth doing deserves your best shot. Do it right the first time. When you're done you will know it. { I'm just the guy who thinks he knows everything, my buddy is the guy who knows everything.} cheers jimmijim*****SDC***** member

                            Comment


                            • #15
                              What does "CASO" stand for? I assume it means cutting corners or doing poor work.

                              Comment

                              Working...
                              X