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Thread: Tuning or Valve Float? Help

  1. #21
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    I built a stroked motor last week and I double checked my preload on this one. I used a regular of the shelf roller lifter from epw. My break in is almost done so I'll be testing the rev limit on that. Smaller Cam went in this engine to match the longer stroke and reduced rod ratio so I'm not shooting for high rpm, but I'd like to see 6600. I blueprinted this motor a bit on the tight side and balanced it very closely, so it should do well. I'll almost to SEMA (drove it down from Seattle) so I have plenty of miles on it. I took the coastal highway to minimize time spent at one rpm or gear. This is in my 05 ctsv with a mp112 supercharger, 9.4:1, Manley Stroker kit, trick flow dual springs, kelford Cam, headers, etc.

  2. #22
    Quote Originally Posted by Maxwell Power View Post
    Fixed mine last week.
    Upon installation of the cts vr lifters, I had float around 6100. I gained two hundred rpm when raising my spring pressure... Not enough that's for sure.
    I checked my preload last week and it was .080" ... oops. Not sure how I screwed that one up. New 7.350 push rods (old were 7.40) and I'm rev happy.
    Preload won't change the float rpm, it will just reduce how far it can float, and how quickly it can recover.

    200RPM from additional spring pressure? (What springs did you change from / to) ?

  3. #23
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    Quote Originally Posted by Andy0x1 View Post
    Preload won't change the float rpm, it will just reduce how far it can float, and how quickly it can recover.

    200RPM from additional spring pressure? (What springs did you change from / to) ?

    Incorrect much?
    In a general way, yes.
    However when you over preload a lifter it doesn't behave properly. Valve wasn't floating, it just wasn't shutting.

  4. #24
    If it wasn't shutting, you weren't just pre-loaded, you were bottomed out.

    There are three ways to preload a hydraulic lifter. The most common is the factory procedure that places the preloaded piston in the center of the piston travel with roughly 11/2 turns of preload. The second method is a 1/4-turn (roughly 0.010 inch) preload of the lifter. The third preload technique is to push the lifter plunger all but about a 1/2 turn (0.020 inch) from the bottom of the lifter. This last idea has been championed by drag racers forced to use hydraulic lifters who have experienced power loss caused by lifter bleed-down rather than pump-up. The theory is that by eliminating all but the last 0.020 inch of plunger travel, the hydraulic lifter acts closer to a solid roller lifter. Godbold says that for a drag raceƻstyle engine with quality parts, good springs, and precise, highrpm control of the valvetrain (no valve float), this last preload idea is one of the best ways to extract the most performance from a hydraulic lifter. Let's look at why this works.

    Godbold says Comp's Spintron testing experience has revealed that a taller column of oil in the lifter (minimum preload) will contain more air mixed with the oil than will a shorter column of the same oil. A hydraulic lifter operates on the principle that oil is incompressible. We know air is easily compressed, so high-rpm valvetrain inertia loads are able to compress the air in the lifter and push the piston down. Godbold says this movement might be 0.030 inch or more at the lifter, which when multiplied by a 1.5:1 rocker ratio could be 0.050 inch or more of lost valve lift that equals a loss of power. A large amount of preload radically shortens the column of oil and reduces the potential loss of valve lift. However, if the engine experiences even trace levels of valve float, the lifter piston could push up 0.070 inch (or more). That can hang the valve way out, causing valve-to-piston damage.


    Read more: http://www.carcraft.com/techarticles...#ixzz2AvixJg2i

  5. #25
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    I think we're saying the same thing just using different terms.

    Yes it was too much preload which is probably very close if not bottomed out.

    regardless, putting in the shorter push rod fixed it. I had too much preload... whether or not it was bottomed, I don't know as I didn't measure the total depth. I just targeted .035" of preload and it fixed my problems.

    edit: checked my numbers. 0 lash was 7.315. I have 7.350 pushrods. The lifters are noisier for sure and I'm thinking of going up another .010-.020 to see if it quiets it down some.
    Last edited by Maxwell Power; 11-08-2012 at 04:39 PM.

  6. #26
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    This chart http://ls1tech.com/forums/attachment...er-preload.jpg

    says I should be running much more than that.

  7. #27
    Senior Tuner 5_Liter_Eater's Avatar
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    Thats weird. I target ~.040".
    Bill Winters

    Former owner/builder/tuner of the FarmVette
    Out of the LSx tuning game

  8. #28
    Advanced Tuner ProTools4's Avatar
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    I set preload with the engine running by ear, *LT1*
    verified by a large diameter hi rez vacuum gauge
    backed up by years of exp, doing running adjustments
    backed up by dyno testing

    CTSV lifters were like power poison to my combo

    CTSVR lifters must have a specific set of parameters met to work correctly
    NotoriouSS TAD
    DATLS7N 73' Datsun 620 LS7/HNC/TR6060/4.10/T2/2450lbs/603RWHP
    J5 - 96' Impala SS - 4700lb autocross machine
    Langston - 96' Caprice 9C1 Beater
    Rosie - 67' El Co - race truck w/ plates
    Wall-E - 21' Tesla Model 3P

  9. #29
    I had to go from Comp 105, to Comp 130 springs after doing no other mods than the CTS-VR lifters.

  10. #30
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    Quote Originally Posted by Andy0x1 View Post
    I had to go from Comp 105, to Comp 130 springs after doing no other mods than the CTS-VR lifters.
    that's because preload DOES affect float rpm. But not float from valve train weight, cam profile and rpm, but float from lifter pump up not letting the valve shut.

    I think it's pretty obvious that these CTSV-R lifters pump up more than other lifters. This is why so many people are having problems with them.
    Get the preload correct and it's not an issue.

    Protools4, So what? LT1 has no bearing on what I'm doing here. I'm glad that your years of experience are so important to you that you feel it's relevant on an engine that isn't adjustable while running. Unless I was to upgrade to a whole different rocker type assembly, the only method of adjustment I have is push rod length.

    I asked a couple questions I got this:
    a couple guys with no clue, but claim they know it all.
    another guy with attitude because I'm obviously wasting his bandwidth
    another guy with all this "experience" that doesn't even provide any useful information.
    a couple guys who tried to help and were polite. l like those guys.

    I can't help but be a little bitter.

  11. #31
    Advanced Tuner ProTools4's Avatar
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    Your Welcome

    NotoriouSS TAD
    DATLS7N 73' Datsun 620 LS7/HNC/TR6060/4.10/T2/2450lbs/603RWHP
    J5 - 96' Impala SS - 4700lb autocross machine
    Langston - 96' Caprice 9C1 Beater
    Rosie - 67' El Co - race truck w/ plates
    Wall-E - 21' Tesla Model 3P

  12. #32
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    Lol

  13. #33
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    You sure don't seem very appreciative of the help offered on this forum.
    Last edited by superwagon; 11-14-2012 at 09:58 AM.

  14. #34
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    I am very appreciative when help is offered, even more when it is correct and without attitude.

  15. #35
    Advanced Tuner ProTools4's Avatar
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    so did you resolve the issue without a lifter change?
    NotoriouSS TAD
    DATLS7N 73' Datsun 620 LS7/HNC/TR6060/4.10/T2/2450lbs/603RWHP
    J5 - 96' Impala SS - 4700lb autocross machine
    Langston - 96' Caprice 9C1 Beater
    Rosie - 67' El Co - race truck w/ plates
    Wall-E - 21' Tesla Model 3P

  16. #36
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    yes sir.
    Shorter push rods did the trick.

  17. #37
    Again; Preload does not affect float RPM.

    By shortening your pushrods you have reduced how far your lifters can pump up (if at all)

    Either you have 'reduced' how 'far' the valves are floating above the seats (to the point of not noticing it?), or you have shortened the rods so far that they are no longer capable of causing a float condition. (and you're experiencing increased valve train noise.)

    Note; you mentioned an increase in the noise which would lead to the: too short of a push-rod scenario. The result of this would be no float, but reduced lift (from design spec.), and the constant chatter of the valve train slack. This is hard on parts.

    It sounded like you had at least some amount of pre-load though, so it's hard to say. Are you certain the valve was closed when you were doing your measurements?
    Last edited by Andy0x1; 10-19-2013 at 08:23 PM.