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Thread: *350 sbc Valve Ajustment*
          
   
   

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  1. #1
    zippi's Avatar
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    *350 sbc Valve Ajustment*

     



    After finally finding the PO I'm told the engine in my pickup is a 1971 350 block with a 283 crank making it a 302. My truck was running fine prior to adjusting the valves. I was trying to get rid of a little clatter a couple valves had. I was trying to adjust the valves that I'm assuming are hydraulic by loosening the nut until it clatters, tighten until the clutter stops plus 1/4 more. Just will not run right. I have tried 1/2 more after the clatter stops but it runs worse. I was thinking they may be solid lifters but was told it probably would not have ran tightening the valves down that much. Looking for a little help.

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    NTFDAY's Avatar
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    Quote Originally Posted by zippi View Post
    After finally finding the PO I'm told the engine in my pickup is a 1971 350 block with a 283 crank making it a 302. My truck was running fine prior to adjusting the valves. I was trying to get rid of a little clatter a couple valves had. I was trying to adjust the valves that I'm assuming are hydraulic by loosening the nut until it clatters, tighten until the clutter stops plus 1/4 more. Just will not run right. I have tried 1/2 more after the clatter stops but it runs worse. I was thinking they may be solid lifters but was told it probably would not have ran tightening the valves down that much. Looking for a little help.

    It will run but like crap. Try running .008 on the intake and .0012 on the exhaust.
    ted dehaan and glennsexton like this.
    Ken Thomas
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    zippi's Avatar
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    Quote Originally Posted by NTFDAY View Post
    It will run but like crap. Try running .008 on the intake and .0012 on the exhaust.
    Thanks. There is a lot of mixed answers on what they need to be set at from some of the other forums so I think I'll start with .020 and see how it goes.

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    Quote Originally Posted by zippi View Post
    Thanks. There is a lot of mixed answers on what they need to be set at from some of the other forums so I think I'll start with .020 and see how it goes.
    The setting I gave you are for a 63 "Fuelie" cam I had a long time ago. The most radical I can think of is the 30-30 cam used in the 64 Corvette. I have looked at your post on hotrodders and as usual the so called experts over there are all over the place. Good luck.
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  5. #5
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    zippi;
    I suggested you start at ".020", did not say that is your setting, .020 will usually be safe to start as your cam's settings are unknown.
    I also suggested you try an "Old time way of adjusting valves with vacuum gauge"; back off till they tick (at idle), tighten/loosen slowly to highest idle vacuum, run the rack (all valves) several times adjusting slightly to get highest vacuum or until there is no change in vacuum readings.
    Believe it or not, your vacuum gauge will tell you the valve clearance needed by using the above method then measuring the clearance with a feeler gauge for future.

    JMHO; keep in mind by your own words "you have not done this for a number of years", and with the problems you're having, I would not recommend the one revolution (#1tdc - #6tdc) method for adjusting valves (in fact I don't recommend it at all). Use the two revolution method, it assures the valves for the cylinder being adjusted are actually closed.

    Further, may I suggest you slow down and try one method at a time, and not combine several different methods together.

    Also there is a strong possibility, "Mr. Techinspecter1" was correct when he told you your cam may be going flat. I know it's not what you want to hear, but check your oil for metal (looks like metallic or metal flake paint).

    And PLEASE, as you go forward, keep a log of all the details about your car's specifications, motor, running gear, oils, plugs, fuel, exc.. You will appreciate it in a few months when you have forgotten, and the next owner will too.
    NTFDAY, johnboy, 34_40 and 2 others like this.

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    Quote Originally Posted by zippi View Post
    After finally finding the PO I'm told the engine in my pickup is a 1971 350 block with a 283 crank making it a 302. My truck was running fine prior to adjusting the valves. I was trying to get rid of a little clatter a couple valves had. I was trying to adjust the valves that I'm assuming are hydraulic by loosening the nut until it clatters, tighten until the clutter stops plus 1/4 more. Just will not run right. I have tried 1/2 more after the clatter stops but it runs worse. I was thinking they may be solid lifters but was told it probably would not have ran tightening the valves down that much. Looking for a little help.
    ((I was trying to get rid of a little clatter a couple valves had. I was trying to adjust the valves that I'm assuming are hydraulic by loosening the nut until it clatters, tighten until the clutter stops plus 1/4 more.))

    First, you need to know for sure if they are hydraulic, or solid. Period.
    With the valve cover off, the one where no. 1 cylinder is located. Now hand rotate, or bump the starter until it is close to TDC. Then, turn it until the marks are at TDC.
    Once you are sure the valves are seated for that cylinder, on TDC, with no load, you then apply steady pressure to the rocker side where the pushrod is. This with steady pressure downwards, will slowly bleed the oil out of the lifter. This will confirm very easily if they are truly hydraulic lifters...
    As you said, you only have a couple that made noise.
    There is much more about lifters, but, this is short to find out what you have.

    Other things like how many miles on the motor ? How many miles until the noise started? Is it low on oil? Are the nuts holding adjustment? Are the studs for the rockers pinned, screw in, things like that. And, have you used a dial indicator to check the rocker amount of movement on each rocker?

    Lastly, even new lifters can have been sized wrong, and create a fast bleed down, and do not pump up fast enough, causing noise. How much oil pressure do you have at idle?

    One other thing is, if you tightened the lifters to fast, they will hold the valve open. This must be done a slight turn at a time with the engine running. The main reason is if they have miles on them, they will build up varnish, sludge, and it doesn't take much, and will not adjust to the new setting quickly.
    With engine running, when you start the adjustment, put slight pressure on the the nut to turn it, you will feel it, easy, hard, pulsating with each Revolution of the running engine.

    And, as mentioned, a vacuum gauge is your friend.

    Of course, you may have a lobe or 2 that has worn. But, you won't know until you check things out a step at a time starting with basic things... That is all.
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    DennyW is offline CHR Member Visit my Photo Gallery
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    I second this...
    ((I have looked at your post on hotrodders and as usual the so called experts over there are all over the place. Good luck.))

    No, I triple it...

    When you don't know, you have to start with the basic checks. That's the only way you will know. Many people say many ways to do it, but, it doesn't matter really. If you don't know what the basics of what you have, you have to start there...
    Last edited by DennyW; 11-06-2018 at 11:04 AM.
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  8. #8
    wrp
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    I agree with Denny. I wrestled with this a long time. Found out of 1,000 videos on you tube, 999 were wrong. The advice above is spot on. One thing I would do and you may not like it, is pull the intake, the push rods and the lifters, check the pushrods for straightness, check the lifters to see if one is excessively worn. I would also check the valve geometry and the rocker arms plus the rocker arm studs. The reason I suggest this is the lack of success you are claiming using reasonable techniques. If something is worn ie cam lobe, push rods, etc. it will never work out. Another suggestion is to look up Blackstone Labs, get an oil sample test kit and send a sample to them. They will tell you straight away, normally in a couple of days, if there is some excessive wear in your valve train or components. The solution to mine was replace the lifters, push rods plus the rocker arms, and rebuild the engine which was full of metal shavings. The advantage was by catching it I was able to not destroy the engine. The rocker arm studs were screw in so they were okay but I did replace the locknuts. At the end of the day the solution was to tighten them more than I thought because of my inexperience. This is just an opinion with an objective to support what the guys above are saying. It was only my experience.

    IMG_1078.jpgIMG_1082.jpgIMG_1080.jpgBroken IMG_1054 (1).jpg
    Last edited by wrp; 11-10-2018 at 10:08 PM.
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  9. #9
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    Ok guys.....here is the update on adjusting my valves. I adjusted the valves per the procedure below. I set both the intake and exhaust valves at .020 cold. I'll be damned if it don't run like it did before I started adjusting the valves. So far I am a happy camper. I let it get a little warm and took it out for a run. I didn't get on it to hard but man does it pull and sound like it did before. When I got back I listened to the engine and like before it has some engine noise which now since I know it's not hydraulic I'm fine with it . I did hear something on the right bank that sounded like an exhaust tic. I'll investigate that further tomorrow but for now I'm satisfied. Thanks for all the input.

    Get #1 to Top Dead Center

    Exh.- 1 – 3 – 4 -8​
    Int.- 1- 2 – 5 - 7 ​

    Get #6 to Top Dead Center

    Exh.- 2 – 5 – 6 – 7​
    Int.- 3 – 4- 6 - 8​
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  10. #10
    dave bardo is offline CHR Junior sMember Visit my Photo Gallery
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    i have a 302....all were built with solid lifters with duntof 30/30 cam.....set lash at .030...........i just went thru this on my engine..

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    "30-30" AND OTHER OEM SB SOLID LIFTER CAM VALVE ADJUSTMENT

    (Revised 09-23-2008)
    By John Hinckley and Duke Williams
    The traditional method of adjusting valves one or more cylinders at a time with each cylinder
    at TDC is fine for hydraulics and for most solid-lifter cams, but NOT for the factory "30-30" solidlifter
    cam used in '64-'65 L-76 365 HP and L-84 375 HP (FI) Corvette engines (and in '67-'69
    Camaro 302/290 Z/28 engines); this cam has VERY long clearance ramps that are .017" high,
    and at TDC for any cylinder, both the intake and exhaust valve for that cylinder are still on their
    ramps, NOT on the cam's base circle, which is why the Service Manual for all cars so equipped
    says specifically to set them "hot and running".
    There is, however, a better way to adjust the valves with a "30-30" - you can set them "cold
    and not running" by setting the intakes at 90 degrees ATDC and the exhausts at 90 degrees
    BTDC - so the lifters are on the base circle, not on the clearance ramps. This has been confirmed
    with cam lift/crank-angle diagrams and analysis of the GM drawing lobe data, and I've done mine
    this way - results in a nice mechanical "singing" sound, no "clacking", it runs better, sounds
    better, idle is more stable, and throttle response is improved. Several other Z/28 owners have
    followed this procedure as well since we developed it, and all of them have seen the same
    positive results.
    Set them cold at .023"/.023". The actual measured (stamped rocker arm) ratio at the lash
    points is actually about 1.37:1 (not the design 1.5:1, which is a “theoretical” number), so the
    clearance ramp, which is exactly .017" high on the lobe, is all taken up at .02329" clearance;
    .030" clearance with the valve closed is too loose - the ramp ends/begins before the
    .030"clearance is taken up, resulting in the valve being lifted off and returned to the seat at
    greater than ramp velocity. This will contribute to valve seat recession, and can cause valve
    bounce at the seats at high revs - it will also be noisy.
    You can adjust two valves at each 90-degree rotation point, starting at #1 TDC, turning the
    crank 90 degrees at a time seven times (measure and mark your balancer first at 90-degree
    intervals from TDC). Removing the plugs simplifies rotating the crank, but you were going to
    change them anyway, right? Proceed as follows:
    TDC #1 - 8E, 2I
    90 deg. - 4E, 1I
    180 deg. - 3E, 8I
    270 deg. - 6E, 4I
    0 - 5E, 3I
    90 deg. - 7E, 6I
    180 deg. - 2E, 5I
    270 deg. - 1E, 7I
    Start at TDC #1, then rotate 90 degrees at a time, setting at .023" cold. If you like, you can
    then go back after you're done to each cylinder's TDC position and check clearance on that
    cylinder's two valves, and you'll find that they've closed up to approximately.021", indicating that
    both valves are still on the ramps at TDC, as I pointed out in the beginning.
    Trivia - the point of max inlet lift on the "30-30" cam is at 110 degrees ATDC and 118 degrees
    BTDC on the exhaust side, so the lobe separation angle is 114 degrees (angle between points of
    max lift, not the geometric center of the lobe - the lobes on the "30-30" cam are asymmetrical).
    Addendum (May 19, 2003)
    Lash settings revised 12-14-2005
    Optional indexing for Duntov cam revised 09-23-08 (#1, #6 TDC positions will not work for Duntov cam)
    This procedure should also be used for the LT-1 cam. The exhaust is “on the ramp” at TDC. The inlet is
    not, but just barely. With the Duntov cam this indexing procedure may be used, or both valves may be set
    with the cylinder at TDC of the compression stroke. Adjusting eight specified valves at the #1 and #6 TDC
    positions as discussed in the 1963 Corvette Shop manual is only valid for hydraulic lifter cams. It will not
    yield accurate settings with any mechanical lifter cam because not all the specified valve’s lobes at these
    two positions are on the base circle due to mechanical lifter cams’ long constant velocity clearance ramps.
    This indexing procedure on page 1 may be used with ANY cam to assure that the lobe is on the base circle,
    and MUST be used for cams with very long clearance ramps.
    The following inlet/exhaust valve clearances are recommended with the engine cold and not running. The
    difference between “hot” (engine idle speed) and cold clearance on a cast iron pushrod engine is negligible,
    so clearances can be set cold, which is more convenient. These clearances are computed by multiplying
    the height of the clearance ramp (which was determined from analysis of the GM drawings that list lobe data
    to five decimal places every cam degree) by the 1.37:1 measured lash point rocker ratio. The computed
    number is then rounded down. The factory clearances are derived from multiplying the maximum height of
    the ramp above the base circle by 1.5, except the 30-30 cam. The clearances of .025"/.025" listed on the
    drawing were derived from this formula, but the rationale of the published .030"/.030" is unknown. It is
    speculated that the higher clearance was specified to solve idle stability problems on FI engines as the
    larger clearance decreases effective duration slightly, but is definitely tougher on the valvetrain. Idle speed
    on 30-30 cam FI engines should be set at whatever RPM is required to achieve stability, and this will
    probably be in the range of 1000-1200
    When running hard, such as sustained WOT, the exhaust valve head will heat up considerably. About 80
    percent of exhaust valve cooling is through the seat, but the stem temperature will also increase, which will
    cause the stem to grow and decrease running clearance. This is why exhaust clearance ramps are typically
    higher than inlet ramps – to allow for more stem growth and maintain acceptable running clearance to
    ensure the valves fully seat. Since the inlet valve is cooled with every fresh intake charge, its temperature
    and clearance will remain more consistent over the entire engine operating spectrum.
    The rocker arm nut should be tightened until a light drag is felt on the feeler of the same thickness as the
    recommended clearance. Then the clearance may be verified by inserting a .001” larger gage, and if it does
    not go the clearance is between the two gages, which is just right. Note that the inlet clearance specification
    for the 1963 Corvette was tightened to .008” to give a bit more effective duration. This does not need to be
    “factored” anymore. We recommend this tighter clearance for all 327s, and it is optional for 283s for a little
    more top end power though the effect may not be noticeable. Normal engine service will usually result in
    slight loosening of the clearance, and Chevrolet service recommendations from the sixties call out a lash
    check every 12,000 miles as part of a normal tuneup.
    Duntov cam (283) .010”/.016” (lobe clearance ramp heights: .008"/.012")
    Duntov cam (327) .008”/.016” (lobe clearance ramp heights: .008"/.012")
    30-30 cam .023”/.023” (lobe clearance ramp heights: .017"/.017")
    LT-1 cam .016”/.023” (lobe clearance ramp heights: .012"/.017")
    Note: Clearances/clearance ramp heights are listed inlet/exhaust.
    Interesting facts: The LT-1 cam exhaust lobe is the same as the 30-30 cam lobe (both sides identical), but
    the point of maximum lift is indexed four degrees earlier at 122 deg. BTDC. The LT-1 inlet lobe is the same
    at the L-72 cam lobe (both sides identical), but the point of maximum lift is indexed two degrees later at 110
    deg. ATDC versus 108 deg. ATDC for the L-72. The LT-1 inlet/L-72 lobe also has greater asymmetry than
    the 30-30 lobe. The LT-1 cam was, therefore, not "all new", but incorporated two proven lobe designs with
    indexing refinement to broaden torque bandwidth, and the early phased exhaust event compensates for the
    small blocks' relatively restrictive exhaust port. The Duntov lobes are symmetrical and identical other than
    the exhaust lobe having .004" greater clearance ramp height. At any point on the opening and closing flanks
    (the portion of the lobe above the top of the clearance ramp), as measured from the point of maximum lift,
    the design exhaust lobe dimension is exactly .00400" greater than the inlet lobe


    https://www.youtube.com/watch?v=DCxXd5ZpF94
    Last edited by DennyW; 02-27-2019 at 09:39 PM.

  12. #12
    NTFDAY's Avatar
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    I always set then hot.
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  13. #13
    DennyW is offline CHR Member Visit my Photo Gallery
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    Same here. You want everything up to temp for the final adjustment.

  14. #14
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    Wow-----what a read Denny-----------guess as I'm getting older and its harder to bend over those fenders---------come on electric cars!!!!!!!!!!!will we have to check things with a volt/ohm meter??????????????how do we find tdc on electric motors??????

    And I used to get cams ground especially for me with the same lobe diameter base circle so I could change cams without having to adjust lash!!!!!!
    By popular opinions-just a grumpy old man key board bully--But really, if you are going to ask for help on an internet site, at least answer questions about what you are asking about-----

  15. #15
    DennyW is offline CHR Member Visit my Photo Gallery
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    Quote Originally Posted by jerry clayton View Post
    Wow-----what a read Denny-----------guess as I'm getting older and its harder to bend over those fenders---------come on electric cars!!!!!!!!!!!will we have to check things with a volt/ohm meter??????????????how do we find tdc on electric motors??????

    And I used to get cams ground especially for me with the same lobe diameter base circle so I could change cams without having to adjust lash!!!!!!

    Electric car ONLY if you live where it is warm all the time. Otherwise, up north, your trip becomes half a trip... Then, you use your thumb...

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