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Thread: Valve adjustment problems

  1. #1
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    Default Valve adjustment problems

    Maybe you all can help me with this. My 500 caddy in the 442 uses non-adjustable rocker set up much like the ford FE. Has 1 rocker T for every 2 rockers and have to be shimmed to adjust your pre-load. I put big block pontiac valves in my heads 2.25 intakes 1.77 exhaust if I remember right. All valve tip heights are + or - .010" and the pontiac valves are about .015" taller. When I set the motor up last spring I set lifter pre-load at .030". The rockers have always been noisy once the thing gets up to temp. I just lived with it. I bought a set of shaft roller rockers for it but am saving them for another build down the road. Well I over revved the damn thing and bent 4 pushrods so I figured I would add a little more pre-load to the lifters by removing some shims I put under the rocker T's. For every .010 worth of shims taken or added under the T makes .006" difference in pre load at the lifter (have to take rocker ratio in account). I pulled .020" worth of shims which should have added .012" worth of pre-load. Well the damn lifters wont bleed off, once I get three or four cylinders set the starter starts draggin and once all are set it wont start because the pumped up lifters are actually holding the valves slightly open. Anyone ever have problems with the lifters not wanting to bleed off before? Im running LS7 yellow beehive springs take I got from ligenfelter (spelling?) so they dont have alot of seat pressure. They are set at the recommended 1.800 install height, no coil bind or valve float. Cam is very mild only about .525 lift. Only thing I can figure is to pull the intake, take one lifter at a time apart and drain them and see what happens. Was hoping someone knows a quick trick to save me a bunch of work. I have to quit trying to be "different" with these bastard engine builds, they are driving me nuts.

    Robbie

  2. #2
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    Default Re: Valve adjustment problems

    That's a lot to read and I'm confused to say the least. Why not just change out to adjustable rockers? It sounds like you went the long way around that option.

    Sig by RogerStout

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  3. #3
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    Default Re: Valve adjustment problems

    Sorry, on the caddy you have to swap to very large cast aluminum valve covers to clear the adjustable rocker setup. As tight as the motor fits with the stock covers the only way Im getting the larger covers on is to completely delete my heater box and possibly swap to a hydro boost setup due to brake booster to cover clearance. I pretty much choose the lesser of 2 evils I guess. Right now the cars still a streeter and Im not willing to lose my heater or go butching my brake system, so Im trying to stay with the stock setup.
    The stock rockers need to be shimmed up or the rocker T's milled to adjust your valves. My lifters for some reason wont bleed off to allow me to tighten the lifter pre-load up. I set them a .030" (which would equal about a 1/4 turn on a normal small block) and its too noisy once its warmed up. For some reason when I try to tighten the pre-load up at all it will hold the valves open slightly instead of bleeding off the lifter and compressing the plunger farther.

    Robbie
    Last edited by yellowroket; 03-29-2012 at 11:20 AM.

  4. #4
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    Default Re: Valve adjustment problems

    At least now I understand why you chose that route. I apologize for knowing nothing about Cadillac engines other than they are light for a big block. It sounds like the difference in valve length/installed height could have caused the bent pushrods. But then, the lifters should have saved them.
    I don't know any tricks. You would have to pull the lifters like you mentioned earlier to find out if they'll bleed off.

    Sig by RogerStout

    www.bullplayztrading.com

    2004 SRT 10 Red RC Skanky~Hott Car Club President
    #2402 out of 3057, Built 6/4/2004
    Dyno####433/469 at the wheels!!!
    Mopar Nationals 2010 Viper Truck Show Winner
    Mopar Nationals 2011 Viper Truck Show 2nd Place
    Mopar Nationals 2012 No Show
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  5. #5
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    Default Re: Valve adjustment problems

    Thats what I dont understand. When I set it up I used very little pre-load for the fact that I run the shit out of my toys. The lifters have close to .100" of movement inside, setting them at .030" should have left over .070" of movement to prevent holding the valve open in the event of valve float or bottoming out and bending pushrods. I cant figure out why they wont bleed off, thats the whole reason for using hydraulic lifters in the first place. Guess I will just bite the bullet and pull the intake again to see whats wrong. Man I hope its not a lobe wiping or something along those lines. Thanks

    Robbie

  6. #6
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    Default Re: Valve adjustment problems

    Adjustable push rods? More $$ of course.
    Adam K
    '65 Corvair Corsa new DD
    '66 Buick Riviera GS
    '66 Corvair Corsa Corv8
    '84 Buick Regal 3.8 Turbo
    '06 Avalanche Z71 4X4

  7. #7
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    Default Re: Valve adjustment problems

    You're math is wrong....when removing shim under the rocker stand you would need to multiply the amount removed times the rocker ratio...not divide.

    Based on your numbers from your first post you have a 1.66 rocker ratio. Multiply that times .020 and you added .033" to your preload..not .012".

    So if you originally had .030 now you have .063. However with .100" movement within the lifter you should still be fine.

    Did you measure the preload the first time with a dial indicator setup directly on the rocker cup to get a real .030"?

    Seems to me you are simply bottoming out the lifter plunger.....don't pull the intake yet...
    -John


  8. #8
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    Default Re: Valve adjustment problems

    Adjustable pushrods could be an option, but I dont know if they will clear through the head. Would have to check that out.

    John,
    When I built the motor I did use a dial indicator and actually checked every valve. Verified TDC and marked the balancer at 4 places 90 degrees apart and followed the firing order (have to set both valves on a cylinder at once on the caddy). The loosest on was .030" and the tightest was .038". Here is the link I used when I had the larger valves put in and set up the pre-load http://www.cad500parts.com/tech/Valves76cc.pdf. At the bottom it tells how valve over length, push rod, and T-pedestals change pre-load. Damn I wish I paid more attention in school. I will probably still just pull the intake again and borrow my buddys dial indicator just to be safe. Thank you guys

    Robbie

  9. #9
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    Default Re: Valve adjustment problems

    I didn't bother clicking the link...but to clarify this is how I do it:

    1.) Started with a bled down lifter on a lobe that is at it's base circle
    2.) Set the dial indicator with the plunger on the rocker tip and the angle of the plunger is inline with the angle of the pushrod - push the plunger down about .100 and re-zero
    3.) The shaft is not bolted down - it's loose
    4.) There is no preload on the lifter (because of step 3)
    5.) Slowly bolt down the shaft ass'y and watch the amt that the rocker tip pushes the pushrod into the lifter

    That is the lifter preload... .030" is a good number.

    If your valve heights are within .010 that is decent and should work.

    Are the lifters you're having problems with the same ones that threw the pushrods?
    -John


  10. #10
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    Default Re: Valve adjustment problems

    Any updates Robbie?
    -John


  11. #11
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    Default Re: Valve adjustment problems

    I got another dial indicator and went through the entire valve train. I pulled all the lifters bled them down in a vice and set all lifters with .045 pre-load. Fired it up and the damn things was still ticking but was much better. Drove it to work one day and took it up to the dyno day last weekend. Constant slight ticking noise not matter where I set the pre-load. Take it out today for a spin and a couple miles from the house the freaking thing starts missing, loses all power and starts hammering hard. I pull over pop the hood and it sounds like a rocker is coming through the valve cover. Turn the car around and start limping it back to the house. I go about a mile or so and the things quits missing/ hammering and sounds fine. Get it back to the house open the hood up and there is no valve train noise what so ever. Take it out for another spin and come back, the damn things chattering again.
    All this time I have been chasing the noise thinking its a pre-load/ valve adjustment problem but now I think its a dang lifter thats been bleeding off and happened to collapse today. Now I have to figure out what to do next. I want to do a cam swap to a larger one but that details new cam, rockers, pushrods, valve covers and pulling the motor plus costing most of the season this summer. Or I can put in new lifters, re-break them in and pray I dont lose a lobe during the break in. Kinda sucks either way. I am getting tired of paying the price to be different with this caddy motor.

    Robbie

  12. #12
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    Default Re: Valve adjustment problems

    Put new lifters in, re-broke the cam and all seems good for now. We will see how long it lasts.

    Robbie

  13. #13
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    Default Re: Valve adjustment problems

    Well a long time we hope, I know you don't really want to repeat this procedure again
    Adam K
    '65 Corvair Corsa new DD
    '66 Buick Riviera GS
    '66 Corvair Corsa Corv8
    '84 Buick Regal 3.8 Turbo
    '06 Avalanche Z71 4X4

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