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    Rocker arm installation questions

    So, I swapped on some GT40p heads and headers onto my HO box. I go to install rockers and I was not getting correct torque when installing rockers. So, I purchased a shim kit (PN#M-6529-B302), and I am getting my torque correct at 3/4 of a turn with a .030 shim on every rocker arm.
    My problem is when I'm reaching torque after I took all the slop out, cam on base circle so lifters are even and in neutral positin, and torqued to 20 ft/lb I notice it starts to hang the valve open a tiny bit on some cylinders. Is that OK since I pumped up my lifters by priming the oil pump? I say no but I've never had this problem on any other 302 I've done, but I can't say I've really noticed or payed much attention to it also. I've kinda just bolted, torqued, and let it ride. Maybe I'm just being to up tight this go around. Any help is appreciated! The heads are GT40p heads, decked .015, 3 angle valve job, and that's about it, pushrods are factory HO length Manley pushrods.

    #2
    Thinner head gasket? Guess I'm confused by your 3/4 turn comment. Pedestal rockers just get torqued down. No lash adjustment like poly locks.

    Stack two shims?

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      #3
      No, NOS Ford explorer top end gasket set. To get correct torque with pedistal rockers you have to be within 1 full turn to a 1/4 turn once all slack is removed from rocker for correct torque. No, stacking shims throws the geometry off further, as every .015 underneath the rocker is 1/4 off to receive correct torque value and i am within Fords 1 full turn to a 1/4 turn for correct rocker torque.

      I guess my question simplified is, since I pumped up my lifters is that where I messed up in making some valves hang open slightly since I took all the play out of the lifters in getting my readings with the lifters at full pumped up height vs the lifter being bled down? If that makes more sense.

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        #4
        Is there a Ford spec number for torque?
        What I Own: 1993 Mercury Grand Marquis GS
        What I Help Maintain: 1996 CV / 1988 CV / 1988 Tempo

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          #5
          Yes, it's 17-23 Ft/lb within 1/4 to a full turn once all slop is taken out of rocker by hand.

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            #6
            The rule of thumb I recall following was 20 ft/lbs and no more than a half-turn on the torque. I followed that on my E7s and TecNickal's GT40 heads. I know my E7s were not decked, and I cannot recall if his heads were resurfaced by any appreciable amount, but I know they were cleaned up.

            I know I had to use a shim or two on my E7s since I used Crane roller rockers, but on the GT40 heads we just reused all the original bits without trouble. However, I did not have the lifters pumped up on either engine. Both ran well after everything was done.

            Only thing I could consider is since your heads are decked a touch, perhaps the stock length pushrods are a little too long for the application now.


            My Cars:
            -1964 Comet 202 (116K Miles) - Long Term Project
            -1986 Dodge D-150 Royale SE (112K Miles) - Slowly Getting Put Back Together
            -1987 Grand Marquis Colony Park LS (325K Miles) - April 2017 + September 2019 POTM Winner
            -1997 Grand Marquis LS (240K Miles) - The Daily Workhorse & March 2015 + January 2019 POTM Winner

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              #7
              Because you're just running them down to a positive stop. There is no adjustment for preload, it is what the tolerance stack determines. Your only adjustment is push rod length... or shims to move the fulcrum. Do you have the intake off, and can you see if the lifter plunger is bottomed out when you get the pedestal torqued?

              Measure the pushrod length for every application is my only recommendation, there are just so many variables. Something changed. You mentioned a valve job, did this involve any actual replacement valves or seats? Did your machine shop use a chevy valve?

              Edit: i had a thought.... Is it only hanging an intake valve open? If your shop swapped springs putting it back together, exhaust on intake, you have basically no seat pressure, since the stock spring is sorter on the exhaust.
              Last edited by JeffBoudah; 01-22-2022, 05:47 PM.

              Comment


                #8
                You can guesstimate preload based on the amount of travel from zero lash to proper torque. The final word is to confirm the preload with a dial indicator though. Off the top of my head I want to say its .020 to .060 inches for lifter preload, but confirm with either the manual or whoever made your lifters.

                should definitely not be hanging the valves open though. Lifters don't exactly pump up solid unless they are being fed pressurized oil. Without that you're just dealing with the spring inside, which should definitely be softer than the valve spring. Unless that bottoms out it can't open the valves.


                I ended up needing longer pushrods for my E7 w/ roller rockers setup. The set had enough differences rod to rod that I had to do the preload on each valve. Some have no shim, some have the thin, some have a thick. It was a pain in the ass but once I got it all set correctly the engine ran quieter than it ever had.
                Last edited by gadget73; 01-22-2022, 09:45 PM.
                86 Lincoln Town Car (Galactica).
                5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

                91 Lincoln Mark VII LSC grandpa spec white and cranberry

                1984 Lincoln Continental TurboDiesel - rolls coal

                Originally posted by phayzer5
                I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

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