Re-using old shims during valve lash adjustment? 95MTX

Discussion in 'Gen 1 & 2 - Engine, Exhaust, Drive Line & AC syste' started by revhardSHO, Dec 11, 2017.

  1. revhardSHO

    revhardSHO SHO Member

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    The top end has been torn down (did notice someone has been in here before) but the shims have never been adjusted. Car has 168K on it, and my plan is to re-use the old shims since everything on the front head is within spec as it sits, so I will just be flipping the shims and going from there. I am re-using the intake gaskets and valve cover gaskets as they look relatively new. Budget build for sure. Re-gaping the double platinum plugs only new part will be spark plug wires. Autozone has them for $35, but at that price I have my doubts. What are people using these days? Something mid-range would be preferable.

    I assume this is okay to do, but I just wanted to double check and see if there was anything else I should do before I seal it up again.
     
  2. AREA 91

    AREA 91 PA SHO SHOP

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    If the shims look good, I wouldn't bother flipping them.
     
  3. revhardSHO

    revhardSHO SHO Member

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    Most of the shims look fine, but they are showing their age, as this is a 168,000 mile SHO. I figure if I have gone this far, I have the valve adjustment tools and the perseverance to see this through. I have seen cratered shims and camshaft damage on higher mileage SHOs where the valve lash was neglected, If I'm in here I want to at least be running on new material as the engine will be seeing sustained high RPM operation for many years to come.
     
  4. zoomlater

    zoomlater SHO Member Supporting Member

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    I have not tried Duralast, but a search on the internet for that brand did not look so good. The AC Delco 826Q wires look just like OEM and were not that expensive. The link half way down has recommendations

    https://shoforum.com/index.php?threads/my-car-is-evil-too.130862/#post-1437954

    "Plug wires successfully used around the forum:
    Motorcraft WRE-4081, AC DELCO 16-826Q, or TAYLOR (TAY-74268, TAY-74668)"

    if you do a search on ebay for AC Delco wires, there is a listing with a photo showing how close they look to OEM. They don't have the cable wires marked on them like the OEM ones
     
    Last edited: Dec 11, 2017
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  5. rubydist

    rubydist SHO Master Staff Member Super Moderators

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    I recall that guys have reported that the side of the shim that has the thickness number will wear more easily than the other side. I don't know if that is accurate, or why it would be if it is true, but I agree with Area 91 that if there is no pitting, I would not flip them over.
     
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  6. revhardSHO

    revhardSHO SHO Member

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    I just don't agree with that logic. Remember this is a 60K mile service and it's way over due, and you are telling me not to worry about the shims? What is this some sort of kindergarten? A proper lash adjustment, especially at higher mileage, should include "fresh" shims for every bucket. But only if you want your car to go the distance. Sure, plenty of SHOs run well over 200,000 with no valve adjustment, but I'm not going looking for trouble.
     
  7. LOUDSHO92

    LOUDSHO92 SHO Master Staff Member Sponsoring Vendor Club Mod

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    Only bother if out of adjustment and then you would need the SHO Source shim kit.

    I have done many valve adjustments ranging from replacing one shim to almost all of them. It really depends.
     
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  8. rubydist

    rubydist SHO Master Staff Member Super Moderators

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    Nobody has said not to adjust them if they need adjustment. What we are saying is not to flip them over just for the sake of flipping them over. Putting new shims in just because they are old is like saying you should tear down your 25 year old house and replace it because its not new.

    I've checked valve adjustment on more of these motors than I can remember, and I can count on one hand how many individual valves out of all of those needed to be adjusted. In fact, I have swapped cams and only needed to adjust a few of the valves after that.

    Unless there is pitting on the existing shim with the correct lash, there is no reason to replace it or flip it over, imho.
     
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  9. zak

    zak SHO Member

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    All the same watch out for pitting on the shims which can in turn mess up the cam lobe tips, any pitted shims should be flipped or replaced.
     
  10. revhardSHO

    revhardSHO SHO Member

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    I'm with SDPATT on this one. I come from a very different school of thought. I've seen plenty of SHOs go out the door with 10-11 shim's replaced and I just don't think that is being thorough enough. It's like changing two or three of the rod bearings and leaving the remaining bearings in there because they still plastigauge okay. Older material is more prone to failure and that is what I am looking out for. As I discovered last night, these shim's I'm replacing (so far I've flipped 13 out of 24) are not pitted but some are whipped. Even though they are still in spec, they need to be replaced. Especially during high RPM operation, you can quickly destroy a 170,000 mile shim in no time. It has to be done right the first time, no exceptions.
     
  11. AREA 91

    AREA 91 PA SHO SHOP

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    I don't flip shims, I replace them. It does help when I have a thousand shims at my disposal. I usually re-shim every valve when I do the adjustment. I also shim na and boosted/n20 sho's differently.
     
    Last edited: Dec 13, 2017
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  12. revhardSHO

    revhardSHO SHO Member

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    I am treating the engine like the race motor that it is. It's going to need to be fresh for some serious, sustained high RPM operation. Not some laissez-faire approach oh lets leave it alone because the valve lash is within spec and so what if it has 170K. Thank you very much.


    EDIT: I have plenty of shims at my disposal; within the range to replace all 24 that currently sit in the motor. But for this engine, I'm going with the flip method and as far as I can tell this works just as well as replacing the shims, so long as the shim as it sits falls within spec.
     
    Last edited: Dec 13, 2017
  13. TimboSHO

    TimboSHO Novice

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    What do you do differently? I remember I tried to get everything as tight as I could while still being in spec.
     
  14. rubydist

    rubydist SHO Master Staff Member Super Moderators

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    Generally, for boosted stuff you want to run the valve clearance on the loose side of the spec, so the valve sits on the seat a little longer. That keeps the valves cooler.
     
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  15. TimboSHO

    TimboSHO Novice

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    That makes sense. I guess I never really thought about it. I did hear somewhere that either the intake or exhaust should be a little looser as well. It's been awhile and I can't remember which.
     
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  16. rubydist

    rubydist SHO Master Staff Member Super Moderators

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    The exhaust valve runs hotter because its got very hot gasses passing over it, while the intake valve gets ambient temp (or thereabouts) air moving over it. So, that is one of the main reasons that exhaust valve clearances are larger than intake.
     
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  17. Toolman

    Toolman Boost it! Staff Member Club Mod

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    I don’t flip shims personally.

    A properly adjusted 200,000 mile shim will Work just Fine at 8000rpm. Use good oil. Change it before it needs it.
     
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