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Engine internal help

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Mr2gtracer
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2014/01/29 08:49:24 (permalink)
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Engine internal help

Hey guys,
 
While my car is off the road (again) I've been looking through some of the build threads on here and it has made me wonder about something I'm hoping someone can explain to me......
 
I have a Gen2 3sgte and a few people that have modified this have converted to shim under buckets while others have used shimless buckets.  What are the advantages/disadvantages of having shimless buckets compared to shim under buckets?

 1990 JDM MR2 GT
 145KW at 9 PSI
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    B24
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    Re: Engine internal help 2014/01/29 09:55:00 (permalink)
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    Hello GTRacer,
    I may be able to shed some light on the advantages and disadvantages.
    Shimless:
    No chance of flicking the adjustment shim out of the bucket at high rpm.
    This is rpm around the 8000rpm limit.
    The shimless is the lightest of the three options.
    Disadvantage is initial cost but this can be helped by a few people on the forum who can provide parts at 'dealers' rates. If you have no luck with people in Australia, there is a U.S. outlet who sells these for $15 each.
    To have the shimless fitted correctly, you will need to have the valves inspected then re seated to ensure its all tight with no shrouding of valves, check guides etc. The valves will then need to be 'tipped' to suit the clearances of the shimless buckets.
    Allow a budget of $800 to have new shims, reco and installation of components.
     
    Shim under bucket:
    These are around 20% heavier than the shimless units.
    A very reliable option which was used on the Formula Altantic Toyota engines for a number of years. so tried and tested option but still has a shim which sits in a 'cup' in the spring retainer.
    Finding a set of shim under buckets and retainers is quite easy and cheap ( eg:I have two sets in the shed)
    You can install these at home if you are keen.
    All specs and procedure available in the workshop manual. 
    You may as well through in a set of Gen3 cams while you are at it as someone who is changing to shimless will also be changing cam profiles.
    Shim under is a good value for money but not as light and reliable as shimless. If you are changing cam profiles, I would go for the shimless buckets.
     
    Now for the shameless plug!
    If you are based in Sydney, need a engine builder machinest for the service, I can give a contact. He has saved my backside and sorted out one of the other guys engines from the forum. His work is excellent and decent guy to boot. If you are in ACT, one of the guys from the MR2 Challenge also provides an excellent service. He built the WTAC engine for the Lotus in 2010 along with many Lotus Elise engines.
     
     
     
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    just_ace
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    Re: Engine internal help 2014/01/29 10:47:12 (permalink)
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    Unless your upgrading your camshafts you don't need to worry about changing them. Even then, most manufacturer's have cams listed for the gen2 setup which have lower lift and less aggressive ramp rate.

    But if your going for a high hp and rpm build which requires higher lift etc or you intend to do some serious track then you'd look at shimless.

    Imho, fitting shimless is easier than shimunder to a gen 2. As they use the same style spring retainer.
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