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289 rocker stud question

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  • 289 rocker stud question

    It looks like I'll be switching to some '65 289 heads on my Cougar. They've had some work done to them like hardened exhaust seats and teflon seals. I'm looking at possibly converting to screw-in rocker studs, too. They are the slot type guides, so I'm wondering if I can get away with just tapping them to 7/16-14 and screwing in the studs, or will it take more than that? Were the bosses on the original Hipo heads cut down relative to the standard 289s? My concern is whether there is clearance for an integral hex nut style stud like the Hipo or if I'd need to use shoulderless studs (assuming I don't do any milling on the bosses). Also, I'm looking at springs that are supposed to be 125lb seat pressure and about 275lbs at my max cam lift (268H Comp Cam). Are screw in studs even worth it at these pressures? Thanks for any insight.
    68 Cougar - 289, 4-speed
    '08 Mustang Bullitt #4492
    Previous Mustangs - '98 Cobra convertible, 87 GT

  • #2
    I always thought the rule of thumb was around .500 lift and the required spring pressure before needing to worry about needing screw in studs? Isn't a 268H around .450? 275 lb springs don't seem like it would be worth the hassle.
    1965 Poppy Red Three Peddle Gear Banger
    347 Stock Block Pump Gas Street/Strip 10.44 @ 125.97 Old Combo
    363 Dart Block Pump Gas Street/Strip - 10.11 @ 133.17 so far

    2005 Torch Red Topless Three Peddle 12 valve Monster
    244 Stock Block Pump Gas Street /Street Much Slower


    Current CI Count - 103

    Comment


    • #3
      Yes, 268h is .456 lift. My local engine builder (mostly off-brand stuff) said not to worry, but a friend of mine that's been doing SBF stuff for a long time highly recommended doing it. I keep debating whether to go a little hotter with this engine or just wait to put the money in a 428 in a few years. Leaving them as press in would pretty much assure I wouldn't do anything else to it.

      Thanks.
      68 Cougar - 289, 4-speed
      '08 Mustang Bullitt #4492
      Previous Mustangs - '98 Cobra convertible, 87 GT

      Comment


      • #4
        I think you”ll be ok as well. But if you tap for screw in studs they have to be milled flat first, the slot is removed plus a little extra if I recall.
        Mike Gasdick 69 Cougar XR-7 , 14:1 358W Canfield heads, CalTrac's / split mono's, "Mighty Mite" C4 w/trans-brake. 11.31.so far.
        2010 F150, 4.6L 2wd
        2002 F250 Superduty 4x4 with a spark plug spittin', manifold crackin' , fuse box burnin , 5.4 !

        Comment


        • #5
          I finally made a decision on the studs. I did what my friend suggested and tapped the heads for studs. Well, he was the one that actually tapped them for me on his radial drill. I've got the style of studs coming that don't have the shoulder on them, so we didn't need to mill the bosses down. He did this previously on a 289 where he ran a Comp Cam 292H, Crane roller rockers and the factory slots for guides. He said he ran it this way for about 60k miles until he sold the car and never had any issues with it. Once we started pulling the studs out, I was glad that we had done it. A couple of the rockers appeared to have been loose at some point in the past and gauged the studs a bit. Now I just need to make sure everything is really clean and make sure the threads get sealed and loctited so I don't get any coolant leaking past them.
          68 Cougar - 289, 4-speed
          '08 Mustang Bullitt #4492
          Previous Mustangs - '98 Cobra convertible, 87 GT

          Comment


          • #6
            Nice not having to worry about it. How long until the engine is together?
            1965 Poppy Red Three Peddle Gear Banger
            347 Stock Block Pump Gas Street/Strip 10.44 @ 125.97 Old Combo
            363 Dart Block Pump Gas Street/Strip - 10.11 @ 133.17 so far

            2005 Torch Red Topless Three Peddle 12 valve Monster
            244 Stock Block Pump Gas Street /Street Much Slower


            Current CI Count - 103

            Comment


            • #7
              Hopefully in a couple of weeks. Ran into some issues with different valve stem heights, so I'll have to do some geometry adjustment with keepers, shims and pushrods. I have to get the rest if the car back together before I can fire it up, too.
              68 Cougar - 289, 4-speed
              '08 Mustang Bullitt #4492
              Previous Mustangs - '98 Cobra convertible, 87 GT

              Comment


              • #8
                Originally posted by Steve68Cougar View Post
                Hopefully in a couple of weeks. Ran into some issues with different valve stem heights, so I'll have to do some geometry adjustment with keepers, shims and pushrods. I have to get the rest if the car back together before I can fire it up, too.
                How can you have different valve stem heights???

                Ryan
                Quality means doing it right when no one is looking. - Henry Ford

                Comment


                • #9
                  Originally posted by Ryan Wilke View Post

                  How can you have different valve stem heights???

                  Ryan
                  The valves are all the same as far as overall length. The difference in height is from machining differences from one to the other. Some valves have been ground more than others (margins all still look OK, but there is some difference) and the machining on the heads varies a bit when they were cleaned up last time. It's not ideal, but it's what I've got to work with.
                  68 Cougar - 289, 4-speed
                  '08 Mustang Bullitt #4492
                  Previous Mustangs - '98 Cobra convertible, 87 GT

                  Comment


                  • #10
                    Ahhh,,,, I gotcha.

                    Reminds me of a FE 390 rebuild I went through some years ago that the machine shop doing the valve job sunk one of the valves so much that there NO gap at the rocker arm.... I ended up grinding off WAY MORE than I wanted to off of the cast-iron rocker arm tip to gain some clearance when the valve was supposed to be closed.

                    Ryan
                    Quality means doing it right when no one is looking. - Henry Ford

                    Comment

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