Announcement

Collapse
No announcement yet.

figuring out push rod length?

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

  • figuring out push rod length?

    I got the head milled down to 3.416 to give me a 9.5 CR for std bore engine (i.m .20 over so it is close to 9.6 for me)
    the cam is the BP 290 cam which has .264 lift on both intake and exhaust
    tappet clearance E:0.016 I:0.014

    BPNW uprated lifters

    Rockers rebuilt by rocker arms unlimited. I did replace arms 2 and 4 with the uprated ones from moss. i reamed them out to match the new rocker shaft. (see cam install thread for why i had to replace them)

    The car came with the tubular pushrod (BPNW said i could reuse them with the new lifters, cam and rebuilt rockers.) I haven't been able to figure out a good way to measure the effective length but they are 8.250 inches long from tip to tip.

    I got the cam installed and i believe it is timed right (i get .014 lift at 37 before tdc)

    I am trying to set the rocker clearances and i am not able to get some of the rockers adjusted.

    Rocker - (correct means i was able to set the right clearance, a number means that is the most clearance i could get before the adjuster ran out of threads)
    1 - .012 is the most I can get
    2 - Correct
    3 - .004 is the most i can get
    4 - correct
    5 - correct
    6 - 0.0000 i can't get the rocker off the valve
    7 - 0.0000 i can't get the rocker off the valve
    8 - correct
    9 - correct
    10 - 0.000 I can't get the rocker off the valve
    11 - 0.000 I can't get the rocker off the valve
    12 - correct


    Any advice? I am guessing i need to replace the push rods with shorter ones but what size?

  • #2
    Have you measured the pedestal's height and compared them ?
    Driving a 1973 TR6
    Doing ZS carb repairs
    email kencorsaw"at"aol.com

    Comment


    • #3
      I used a pushrod that was modified to set the proper length of the pushrods. It's been a couple years since I performed the camshaft install and I don't have all my notes handy. Your cam manufacturer will have the lift measurements. See my first photo for how I set up the indicator to get the proper length. The TR6 Competition Manual has a section on how to build this device. Fortunately my cam manufacturer loaned me the tubular pushrod tool I used in the photos. Third photo was used to confirm length and that the camshaft was oriented properly to obtain maximum lift.

      Also you should not have to actually replace your tubular pushrods. Your machine shop will cut them to size one a lathe and press the solid ends back into the tubes.


      Last edited by ibjean325; 07-10-2018, 09:11 PM.

      Comment


      • jackag91
        jackag91 commented
        Editing a comment
        Sadly I am getting ready to go back on the road, so the price to order an new set and have them in hand is worth more than having these cut (assuming Richard has some in stock)

      • ibjean325
        ibjean325 commented
        Editing a comment
        Hi Jackag91...I am sure that at least three off the shelf pushrods lengths are available. It's been awhile since I looked but Moss Motors UK used to sell them. Confirm the thickness of your cylinder head when new-subtract what you milled off. Confirm the length of the pushrod that was originally installed in your engine (the factory OE part length). That would be at least a starting point to get to how much shorter your pushrods need to be. Find an off the shelf tubular that is close to the length what you need.

        Order the new set close to (shorter) to the amount you milled off the head.

        Couple points:
        The tubular pushrods that came with your engine from the previous owner were the wrong length to begin with.
        Is your cam from a new blank or a regrind?
        Too short or too long will affect your rocker arm geometry.
        Could only quickly find these
        https://mossmotors.com/pushrod-premium-shortened
        But I am sure a search will turn up other lengths. 8.11 comes to mind.
        Last edited by ibjean325; 07-10-2018, 09:56 PM.

    • #4
      Have you measured the cam to be certain it is within spec? Just because it is new does not mean it is was ground to correct specs.
      http://www.lunatipower.com/Tech/Cams/CamSpecTerms.aspx
      1972 Ratty Driver
      Stock 4 Speed
      Bored .20 over
      Stock Cam
      Stock Carbs
      Hubs by Phil
      GP Rear Brackets
      Cable Throttle
      Gear Reduction Starter
      Wire Wheels

      Comment


      • #5
        They measure (starting at the first cylinder pedestal)

        2.077
        2.065
        2.066
        2.068
        2.077
        2.079

        That was in response to poolboy
        Last edited by jackag91; 07-10-2018, 09:15 PM.

        Comment


        • #6
          Originally posted by IGDBOSS View Post
          Have you measured the cam to be certain it is within spec? Just because it is new does not mean it is was ground to correct specs.
          http://www.lunatipower.com/Tech/Cams/CamSpecTerms.aspx

          i might have to recheck it. Can I do it in the car with a dial indicator?

          Comment


          • #7
            Originally posted by jackag91 View Post
            I got the head milled down to 3.416 to give me a 9.5 CR for std bore engine (i.m .20 over so it is close to 9.6 for me)
            the cam is the BP 290 cam which has .264 lift on both intake and exhaust
            tappet clearance E:0.016 I:0.014

            BPNW uprated lifters

            Rockers rebuilt by rocker arms unlimited. I did replace arms 2 and 4 with the uprated ones from moss. i reamed them out to match the new rocker shaft. (see cam install thread for why i had to replace them)

            The car came with the tubular pushrod (BPNW said i could reuse them with the new lifters, cam and rebuilt rockers.) I haven't been able to figure out a good way to measure the effective length but they are 8.250 inches long from tip to tip.

            I got the cam installed and i believe it is timed right (i get .014 lift at 37 before tdc)

            I am trying to set the rocker clearances and i am not able to get some of the rockers adjusted.

            Rocker - (correct means i was able to set the right clearance, a number means that is the most clearance i could get before the adjuster ran out of threads)
            1 - .012 is the most I can get
            2 - Correct
            3 - .004 is the most i can get
            4 - correct
            5 - correct
            6 - 0.0000 i can't get the rocker off the valve
            7 - 0.0000 i can't get the rocker off the valve
            8 - correct
            9 - correct
            10 - 0.000 I can't get the rocker off the valve
            11 - 0.000 I can't get the rocker off the valve
            12 - correct


            Any advice? I am guessing i need to replace the push rods with shorter ones but what size?
            Jack....says --- Tubular pushrods the same length. Some of the valve lash can be met. On some you run out of adjustment.
            My bet here is the base circle, on which the lash adjustment is made from, has different diameters along its length. This can happen with reground cams. Maybe BP can shed some light on this cam.
            Shorter pushrods would be one way to get back some adjustment at the rockers. Raising (shimming up) the pedestals would be another. If you do the later, be sure to include a hole in the shim at the last pedestal for oil to get to the rocker shaft.

            Dick
            Last edited by dicta; 07-10-2018, 09:31 PM.

            Comment


            • #8
              Adjustable push rods for determining the needed length are available at Summit.

              https://www.summitracing.com/parts/tfs-9000

              Comment


              • #9
                https://photos.app.goo.gl/dgh6c5WESTQ6Rcvr9

                so the lift on the first -cylinder exhaust lobe is .284.

                If I am reading the sheet right it says it should be .264

                ​​​​​​

                Comment


                • #10
                  Jack....I personally would get an adjustable length push rod from Summit as David suggest, then you could be certain what your measurement would need to be. ...aside from that, I just rebuilt an engine, shaved the head to 3.40", I'm using a GP2 cam with similar lift as your BP290, but using GP 1.55:1 roller rockers, I'm using TR6 Tubular Chromoly 8.015" Push Rods, (GP # 093)...( .120" shorter than stock US spec TR6)...I had plenty of valve adjustment, not sure if any of this helps you.
                  Jim
                  1973 TR6 CF 1387U
                  Pimento Red, HVDA, Toyota W58 5 speed
                  R200 Diff, GP2/ Hubs/Axles/ Mr Mikes
                  Supplier of Toyota W58 5 speed Transmissions

                  Comment


                  • #11
                    ordered an adjustable pushrod from comp cams..
                    have a call in with bpnw to see if my cam should have .284 or .264 lift (the print is small and maybe I am miss reading it.)

                    I am pretty sure the old cam in the car was a regrind. this is a new cam, so maybe the base circle is bigger and that is why the rods won't fit.

                    Comment


                    • #12
                      Tubular pushrods ought to allow shortening, as the tips are inserted into the tube. I would evaluate the adjustment range on the rockers and cut the tubes to have the desired setting in the middle of that range.

                      I've never measured pedestal heights but am surprised at a discrepancy of 11 thousandths.

                      Tom

                      Comment


                      • #13
                        Originally posted by jackag91 View Post
                        ordered an adjustable pushrod from comp cams..
                        have a call in with bpnw to see if my cam should have .284 or .264 lift (the print is small and maybe I am miss reading it.)

                        I am pretty sure the old cam in the car was a regrind. this is a new cam, so maybe the base circle is bigger and that is why the rods won't fit.
                        Yes, the larger base circle, probably 1.160 on a new grind, would account for the loss of lash adjustment. However, something else must be varying between each rocker to account for this. Shorter and or adjustable pushrods can get you back in the ballpark.

                        Dick

                        Comment


                        • #14
                          just got off the phone with bpnw and it looks like they got a bad batch of cams.

                          They went out to the warehouse and mic'd one out and like mine, it had more lift than it should.

                          Offered to ship me out a new one in 2-4 weeks from now or to swap me out for a the 270 profile and threw in a new head gasket..

                          I ended up going with the 270.

                          They handled a bad situation very professionally. will keep doing business with them

                          Comment


                          • #15
                            "a bad batch of cams" Imagine that.
                            1972 Ratty Driver
                            Stock 4 Speed
                            Bored .20 over
                            Stock Cam
                            Stock Carbs
                            Hubs by Phil
                            GP Rear Brackets
                            Cable Throttle
                            Gear Reduction Starter
                            Wire Wheels

                            Comment

                            figuring out push rod length?

                            Collapse

                            Search

                            Collapse

                            There are no results that meet this criteria.

                            6-Pack Statistics

                            Collapse

                            Topics: 37,609   Posts: 471,525   Members: 8,152   Active Members: 315
                            Welcome to our newest member, TR6_Greer.

                            Upcoming Events

                            Collapse

                            Working...
                            X