Setting installed height

Small Block Mopar Engine

  1. TT5.9mag

    TT5.9mag Two atmospheres are better than one

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    What tolerance do you guys use for setting up the installed height? Comp and Lunati both say +- .020 is acceptable but I’ve got shims down to .005 so why not get them closer? I’m currently setting the installed height on my brand X speedmaster big block heads and they were all over the place as assembled from speedmaster. Glad I checked. Right now my spread is 1.890-1.906. Shooting for 1.900. Thoughts?
     
  2. RammerJammer75

    RammerJammer75 Well-Known Member

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    If you can get them that close I don't see any reason not to.
     
  3. TT5.9mag

    TT5.9mag Two atmospheres are better than one

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    I’m just wondering really where I should stop. Usually I call it good at a .020 spread but my ocd is acting up. A .020 difference in installed height at my spring load is 7.4 pounds. And really the only downside of getting them closer is the time it takes.
     
  4. RammerJammer75

    RammerJammer75 Well-Known Member

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    Could you do an offset retainer/locks to gain some installed height on the shorter ones? Sounds like you can shim some of them pretty close to 1.900. I am one of those people that would try my best to get them all as close to my installed height as I could, so just my thought are to try and tighten the range of heights as much as I could.
     
  5. TT5.9mag

    TT5.9mag Two atmospheres are better than one

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    I could but I don’t like doing that because I like to use all the same retainers and locks on one set of heads and set the height with shims. If I needed .050 across the board I would change retainers or locks but I’m down to changes in the .010-.005 range.
     
  6. RammerJammer75

    RammerJammer75 Well-Known Member

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    Leave the lower ones, shim the others down close to 1.900 and call it. Either that or run it now lol
     
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    • Bobzilla

      Bobzilla Well-Known Member

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      I see you mentioned the variation of 7.4 lbs. I am curious if you are actually checking the spring pressure as well in that 1.90” range to know, or just setting the height and using the math to get that variation?
       
    • turboking15

      turboking15 Well-Known Member

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      I set all my springs up +- .005
       
    • flyfish

      flyfish C8H18+N2O = :-D

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      If I recall correctly, I shimmed mine within 0.010.
       
    • TT5.9mag

      TT5.9mag Two atmospheres are better than one

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      Both. Although my spring checker is hard to read down to single digits.

      Thanks to both of you for chiming in.
       
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      • AJ/FormS

        AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s

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        My experience with .005s is they hammer out. If you use one, put fat boys on each side.
         
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        • TT5.9mag

          TT5.9mag Two atmospheres are better than one

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          I’ll be using comp cams spring locators (which the heads did not come with, just springs on aluminum) and shimming under the locators. Think they (.005 shims) will live between the head and the locators ok?
           
        • gregcon

          gregcon Well-Known Member

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          What I really wonder about is why they were not all the same. In 2020, it's pretty unforgivable to have machine work off that far. It was unforgivable in 1960, too, but things are supposed to get better over time.
           
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          • moper

            moper FABO Gold Member FABO Gold Member

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            If the heights are indeed “all over the place”, I’d be checking the valve job first. Has that been done? How are the stem heights?
             
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            • TT5.9mag

              TT5.9mag Two atmospheres are better than one

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              Agree. But, (there’s always a but) I did buy speedmaster heads and I expected to have to correct some things on them before using them after reading what others here, and elsewhere have written.
               
              Last edited: Dec 16, 2020
            • TT5.9mag

              TT5.9mag Two atmospheres are better than one

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              The stem heights are all perfect, Surprisingly. The valve job, well I’m not a machinist so I’ll defer to you and others. I’ll say it “looks” nice. 9AE35A33-1B3F-4205-8C27-C4B419C388FD.jpeg 902257FC-2FDB-4959-BDDC-0D78DADB3595.jpeg BBA816AD-AA70-4BF2-BB5A-9B61D7E80A8E.jpeg
              If you want pics of anything else let me know.
               
            • TT5.9mag

              TT5.9mag Two atmospheres are better than one

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              Assembled image.jpg
               
            • gregcon

              gregcon Well-Known Member

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              Man,I'd be tempted to smooth out those chambers.
               
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              • yellow rose

                yellow rose Overnight Sensation FABO Gold Member

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                Yeah...I wouldn’t run that valve job.
                 
              • TT5.9mag

                TT5.9mag Two atmospheres are better than one

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                I’m all ears!!
                 
              • MOPAROFFICIAL

                MOPAROFFICIAL FABO Gold Member FABO Gold Member

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                A hair tighter is better than a hair looser..to a point.
                You need to check the spring pressure .
                 
              • TT5.9mag

                TT5.9mag Two atmospheres are better than one

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                That’s exactly how I’ve set everything up for as long as I can remember. Measure the spring pressure, shim to within +-.020 and run it. I am a hobbyist and my tools may not measure as closely as someone with nicer stuff. I have two spring checkers and both have a scale that is hard to read down to the “pound” level. On this set I wondered how far guys really go. Your “hair” and my “hair” may be different by .010 or .020. Really that’s what my original question was. Here’s a better way of asking it, what’s the smallest spring shim you buy?
                 
              • MOPAROFFICIAL

                MOPAROFFICIAL FABO Gold Member FABO Gold Member

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                .015 is the thinnest i use.
                Hardened shims, especially when they're only .015-.030, copper color if using .060
                 
              • MOPAROFFICIAL

                MOPAROFFICIAL FABO Gold Member FABO Gold Member

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                Maybe just by using 60 grit and your finger.
                 
              • MOPAROFFICIAL

                MOPAROFFICIAL FABO Gold Member FABO Gold Member

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                Its 2 angle, not great for transitioning air around the seat.

                A basic 60,45,30 seat angles help the numbers a lot. Add a 15 top and 75 lower if you want.. and it picks up some more.
                 
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