valve lash adjustment

Discussion in 'General Maverick/Comet' started by satchelmcqueen, Mar 11, 2019.

  1. satchelmcqueen

    satchelmcqueen Member

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    so ive watched tons of videos and got tons of different answers. how do i adjust valve lash and set the nut correctly on top of the rocker arm? i followed this video and it makes sense, and i even turned the engine 4 times at 90 degress each turn time. my concern is, that even though each pushrod feels tight and doesnt move, when i turn the nut a final 3/4 of a turn, there are a few nuts i can actually back off with my fingers. theres just no way this wont back off quickly when i crank the engine.

    the only thing i can say that i wasnt clear on was his "zero lash" when turning the nut with each check. when i do absolute zero lash i can still turn the pushrod with my fingers. do i need to keep tightening until i cant spin the rod as well? is this the thing i missed? also a few of the rockers have a slight bit of play from side to side once ive completed 4 complete turns of the engine via crank.

    what am i missing and what works for sure? i dont want to mess this up by something so simple.
     
  2. dyent

    dyent Member

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    Another quick way, tighten until all the up/down movement (play) is taken up, then 3/4 turn. If you have your intake manifold off, look at the retainer ring on top of the lifters, tighten until gap between plunger is approx same thickness at retainer ring.........it is a "feeling" out process, even once everything is tighten correctly, you can turn the push rod if you have strong finger grip, also since your engine has 80k, it is easier to turn push rods than on a motor with all new push rods/lifters/rockers arms........
    If you can loosen "stover nut" by hand, it is time to replace the nut........it is a locking type nut, where the tops are slightly "crushed", so possible the locking part of the adjusting nut is worn, outside chance the thread on stud may have issues too, but most likely its the nut.
    David
     
  3. satchelmcqueen

    satchelmcqueen Member

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    ive been reading some since i posted a sec ago. is it possible i have positive stop studs? it sounds like i might due to what im reading. if thats the case then i just tighten down to the shoulder of the stud then torque to 25ftlbs correct?

    One of them did seem to bottom out when I gave it thw 3/4 turn at the end.
     

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  4. dyent

    dyent Member

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    Yes, you may have those positive stop studs, looks like shoulder below the threads, can not remember what you torque them to, but you seemed to have found all the info!
    David
     
  5. satchelmcqueen

    satchelmcqueen Member

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    anyone else agree with david? this is a motor out of a 70ish f100. i say 70ish because its a rebuilt crate that replaced the stock.
     
  6. dyent

    dyent Member

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    Taken from "how to rebuild your SMALL-BLOCK FORD" by Tom Monroe...........
    "After 68-1/2 the thread on the stud was reduced in size from 3/8-24 (3/8-inch diameter and 24 threads-per-inch) to 5/16-24, but the end pressed into the cylinder head was maintained at 3/8-in. This was designated as Change L4. Because the thread diameter was reduced but the unthreaded end diameter maintained, a shoulder was created at the bottom of the threads. Consequently, the rocker-arm fulcrum is clamped between this shoulder and the attaching nut-it's not adjustable anymore, it is a 'positive-stop' setup. Valves are adjusted in the after-68-1/2 engines by installing longer or shorter pushrods."

    so if the threads on your studs are 5/16-24, then you have the positive stop studs........17-23 ft./lbs.
    David
     
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  7. yellow75

    yellow75 MCCI Oregon State Rep Supporting Member

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    Davids last post is correct, your valves are not adjustable other than changing pushrods .

    When you get your 347 in a few years you will get to do it because just about any head worth putting on it will have adjustable rocker arms.
     
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  8. satchelmcqueen

    satchelmcqueen Member

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    Tha is guys. This is very helpful. I ha e my answer now.
     

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