Looks like I have a coule of beat up valve seats

Discussion in 'Street/strip 400/430/455' started by CJay, Jul 15, 2019.

  1. CJay

    CJay Supercar owner Staff Member

    So the Aquamist car has had some valve train noise in it. The engine has 69 and earlier rocker assys in it with 70 and up hollow pushrods. I figured it was just worn aluminum rockers.

    So I ordered a set of TA steel rocker assys to replace the aluminum ones. Today I took the rockers off and put a straight edge across the valve tips. On the driver's side, the #5 exhaust valve was a little taller than the rest. Maybe .020" or so taller. But on the passenger side, the #4 exhaust was taller by around .050". I wound up putting the steel rockers on and zipping it up for now. I did manage to take a compression test on the passenger side. Results were-

    #2- 180
    #4- 165
    #6- 170
    #8- 180

    Not sure how accurate my compression tester is as it doesn't rest on "zero" but on 30 psi. Remind me to never lend my compression tester to anyone anymore. But I digress....I want to do a leakdown this weekend. On the test drive, the car did seem to run smoother. Would going from 1.6 rockers back to 1.55's make it run smoother or is it just my imagination?

    So what do you think? Im thinking pull the heads at the end of the season
     
  2. hugger

    hugger Well-Known Member

    The heads been serviced at some point I assume? Reason I ask is I've yet to get a set of Buick heads back with equal tip heights I've seen close to .060 maybe I'm just unfortunate but I wouldn't fret too much,..fresh heads always make for a happy little motor!! unnamed.jpg
     
  3. CJay

    CJay Supercar owner Staff Member

    Engine was built in the 90's. That's good news. I was freaking out a bit
     
  4. hugger

    hugger Well-Known Member

    I'm sure they have sunk a little but I'm betting they weren't terribly close to begin with
     
  5. tdacton

    tdacton Gold Level Contributor

    Here is a Positive Energy Drink that works with fresh heads.

    I would have never known who's picture Hugger posted without my son bringing this home and putting on top of our cabinets.
    IMG_2272.jpg
     
  6. TABuickMike

    TABuickMike Michael Tomaszewski Jr

    Obviously haven't had us do a set of heads for you ;)
     
  7. hugger

    hugger Well-Known Member

    My dads heads stage 1SE's I got two years ago were in fact the best I've had they were within .015 of each other
     
  8. Mart

    Mart Gold level member

    I've never had the alum 69 style rockers wear the shafts like the alum 71's.
    I would have continued using the 69's. I liked them better than either the stamped steel or 71 alum's. Plus the added ratio. :)
     
  9. Schurkey

    Schurkey Silver Level contributor

    Other than the two problem children you list, how far apart were the rest of the valve tip heights?

    I bought a set of "new" Enginequest heads for my pickup truck. The exhausts were way lower than the intakes. I sent the heads back.
    [​IMG]
     
  10. Stevem

    Stevem Well-Known Member

    If the heads where rebuilt at some point and if the springs where not shimmed right , or could not be shimmed right due to the amount of valve lift being run then those taller valves are missing a good bunch of needed seat pressure!
    Bouncing uncontrolled valves will beat up there seats pretty fast!
     
  11. CJay

    CJay Supercar owner Staff Member

    The rest of them looked even from my rudimentary measurements

    The engine seems to run well. I'll probably just pull the engine and trans come fall and send the heads out. I can also tear the Muncie apart and freshen that up too. Maybe throw a new disc and pressure plate in it, paint the engine, mill the exhaust manifolds, clean up the engine bay.....the usual.
     
  12. 436'd Skylark

    436'd Skylark Sweet Fancy Moses!!!!!

    The seats are the least of his concerns if the valves are bouncing.. it wont be long until a head pops off a valve and everything is ruined..
     
  13. CJay

    CJay Supercar owner Staff Member

    Im fairly certain that this has been this way for a while. At least a couple of years. Im hoping the engine will hold together for another 400 miles till I yank it in September/ October
     
  14. 436'd Skylark

    436'd Skylark Sweet Fancy Moses!!!!!

    I should have added more to my post. I doubt the valves are bouncing. You likely have a few sinking seats. My point was a bouncing valve was much more dangerous than causing damage to the seat or low spring pressure.

    Lots of folks think the valves slam close. They actually ride the cam and close softly. When they bounce from low spring pressure a catastrophic failure occurs and usually fairly quick. How many hits will a 3/8" stem take before it snaps?

    If you had a bouncing valve the engine would skip and miss at high rpm. Valvetrain noise would not be the only symptom
     
    Last edited: Jul 17, 2019

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