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How to change Valve guides In a 4G63T head

Posted by BogusSVO, Jul 3, 2009

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  1. BogusSVO

    BogusSVO Proven Member

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    How to Change Valve Guides In a 4G63 Cylinder Head


    The first thing is to remove the valves, springs, retainers and locks.

    Picture001.jpg

    The guides are cracked from the bent valves…
    (Sorry about the pic,)

    DSCF3929.jpg

    The tools needed for this is an air hammer, a regular hammer, venire calipers, and the proper sized guide driver.
    Also the replacement valve guides are shown.

    DSCF3927.jpg

    Have the head with the deck side up.
    With the guide driver in the air hammer, knock out the broken guides.
    Take care on not letting the driver get into the head casting.

    DSCF3931.jpg

    Once all the guides are removed, flip the head over. Spray lube/oil in the guide bore (not shown), also lube up the replacement guide. Lightly tap the new guide to start it.

    DSCF3932.jpg

    Once the guides are started, use the air hammer to get them “close” to where they should be.
    I would not recommend trying to hand drive the guide fully into place, damage may occur to the tool, the guide, and/or the head casting.

    DSCF3933.jpg

    Once the guides are close, finish set the guides to the proper height. By measuring from the top of the guide to the valve spring pad using the venire calipers.

    DSCF3934.jpg

    Once all the guides are set to proper height, The head will move on to the next part of the repair, Having the seats cut, so the valve seat will be index to the center line of the guide.
     
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  2. Delta Cam

    Delta Cam Proven Member

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    ohh ohh I see a mazda cam in the back ground ! strike 1 LOL
     
  3. dave99gst

    dave99gst DSM Wiseman

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    You told us to set the guides to the proper height but didn't bother to tell us what the proper height is ?
     
  4. gofer

    gofer Moderator

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    I assumed that when you removed the valve guides from the head you heated it up first. Then before putting in the new valve guides you freeze them so they contract and keep the head heated so it expands, making it easier to press the new ones in.

    Is this true?
    Don't quote me on this but I think its 19.5mm between the top of the valve guide to the valve spring pad.

    :dsm:
     

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  5. RvlutionMtrsprt

    RvlutionMtrsprt Proven Member

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    19.2-19.8mm is what the service manual calls for.

    As for heating the head up, I've been told that's a good way to warp the head. A pretty smart machinist told me his secret to doing guides was to freeze them before tapping them out (c02/liquid nitrogen) and also freezing the new ones before they go in.
     

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  6. silicosys4

    silicosys4 Proven Member

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    I have this question going in another thread, but I think this might be a more appropriate place for this. Right now I'm looking to have all new bronze intake, copper exhaust guides put in a 1g head I'm building.
    My problem is, the machine shop I'd like to go with is telling me that if I don't go with oversized valves after installing the new guides, my valves will be misaligned, won't seat properly, and/or will be "sunk" into the seats. This is apparently due to unavoidable misalignment between the new guides and the original seats. Apparently this can only be solved by going with oversized valves, and milling new seats in the head to match the valves and guides. So anyone on here, what kind of issues have you had with Stainless Steel standard size valves with bronze guides?
     
  7. gixrman

    gixrman Proven Member

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    I just had my head done and it was $80 to replace the guides and $240 to recut the seats and valves and the seats were replaced. I also had the head decked which was an additional $60. I was told and believe that when vavles wear into the seats and you replace the guides it will mis-align the valve to seat contact surface and this is the reason to have the valves reseated. The reason to upsize the valves sound scetchy.
    This was also for a standard 3 angle valve job.

    I appuade the OP for the DIY but this was the least expensive job on my head rebuild and seems like the one of the easiest ways to FUBAR the head.
     
    Last edited: Sep 11, 2011

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  8. arrowhead

    arrowhead Proven Member

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    YES, YES, to alot of stated before

    This is called concentricity when you have to put in new guides, freezing or not or driving them in it depends on the machinist preference, both work.

    the problem arises then with the seats being concentric with the new guides.

    More than likely the original seats will be in bad shape, from the abuse,or plain worn out, pitted or cracked.

    Why not just replace them,since new valves are going in anyways, then take this opportunity and spend a little bit more money, and go to next size valve.

    Many a times I have heard, I just had a valve job done and it is running sh**ty.

    It is blamed on the machine shop when the real couse


    is the customer was advised
    of this and said do the best you can with what I have I can not afford it.

    Valve jobs are not cheap on any 16v heads.
    I have turned away many customers becouse they wanted cheap valve jobs.

    DO it right do it once.
    Go to cedar rapids web or kwik way for more info.
     

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  9. 9!'clipseDOHC

    9!'clipseDOHC Moderator

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    Shouldn't this be a tech article?
     

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  10. BogusSVO

    BogusSVO Proven Member

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    gixrman.... I have installed several sets of oversized valves on the factory seats, after installing new guides, it is not a sketchy thing to do, as long it is done properly.

    you can do new guides and factory seats as long as you adjust the rest of the valvetrain accordingly. IE Valve tip height and spring installed height

    Also you are correct, if the old guide removel goes wrong, you can junk a head quick. I learned that on a 4G head back in 1992/1993, I knocked the guides out the wrong way and tore up the guide bores in the head.

    @arrowhead....

    you bring up alot of valid points....


    The valve guide MUST be index to the valve seat, just not the insert, that is why the valve seat is cut after the new guide is installed.

    The cost of having new seats installed can get costly quick, around my part of the country, to R&R a valve seat will cost between $7-$10 per seat in labor, and then about another $6 for the seat insert.

    The 4G63 head has a sinterd metal or Powder Metal seat insert, and are rather hard, and a true PITA to cut/grind with older equipment (valve seat stones such a a Souix or B&D or the neway cutter) with these hard seats the valve takes the wear more than the seat.

    Some shops still in operation have equipment still in use from the 1950s, 1960s, and the 1970s.. this equipment is too out of date to work on modern alum heads and the seat inserts they have. They will still work just fine on older cas iron heads like small bocks and such.

    Another reason he have heard "I just had a valve job done and it is running sh**ty" is beacuse the machinist did not check the specs, or perform a simple vacuume teast to check for valve to seat seal.

    A properly spec head that is rebuilt will be good as factory or even better. The installer will know with in 5 mins of fire up after the install if the head is done properly.

    It probly should be, I was a noob to the board when I first wrote this, plus it is not in the proper format for a tech article, nor are the pics used saved at DSMTuners.

    I tend to post these on a few diffrent sites.

    If you go here, and check posts # 10 and #17 you will find more links to machine shop write ups I have done.

    http://www.dsmtuners.com/forums/reputation-recommendations/364180-bogussvo.html
     
    Last edited: Sep 15, 2011
  11. arrowhead

    arrowhead Proven Member

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    Exactly what I stated, but I have never really seen any gains from larger valves on a stock seat on the contrary on a flowmaster I have seen the opposite, think about it and you will see it makes sense, the largest restriction to cylinder fill is the valve and if you place a larger valve on a non proper seat you will get reversion we even smooth and round the edges of the valve faces to have a better drop of the mixture into the cylinder.

    This has been my experience. Please do not take this as an argument only that
    less experience guys will benefit from this info.


    Thanks
    arrowhead
     

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  12. BogusSVO

    BogusSVO Proven Member

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    Arrowhead, I understand what you are saying. I have seen a good amount of OS valve installed improperly.

    Some shops are lazy, or do not want to spend the time to do it right.

    The big thing I see is that they do not do a throat cut and open that up, so that becomes the "choke point" and will flow no more than a stock valve.

    The other over looked point is valve unshrouding in the combustion chamber, and that will case the reversion, from the air flow coming off the back of the valve and bouncing back of the CC wall

    When you talke about smothing the valve face, do you mean back cutting the valve? Or polising the valve margin?

    http://www.dsmtuners.com/forums/newbie-forum/341288-why-have-your-valves-back-cut.html
     
    Last edited: Sep 19, 2011
  13. arrowhead

    arrowhead Proven Member

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    OK I think I understand your question if not please let me know.

    I do smooth the valve face to get as smooth finish as i can, I do the same to the valve stem up to the guides mark there I just polish very lightly not to upset
    my clearances.

    I do very light polish on my transition steps but not on my seat angle.

    I like to do 44 degree cut on the valve and 45 on the seat, interference angles,
    The valve face edge is the one that I try to sore of smooth out.I think I am running out of space. PLUS doing all you mentioned before your question.
    Look at all the research by all oem to try disk or flappers or valve opening by selenoids to eliminate that big blockage.I can go further with more but I am at the bottom of the page, I am not very good at this . If this clarifies your question
    Please let me know if not I will try some more.
    thank you
    arrowhead
     

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  14. shadyspeed90

    shadyspeed90 Probationary Member

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    all of this was helpful thanks. i also wanted to add that when realigning valves to the seat ive always used valve grinding compound and spun the valve by hand. this works well if using a new valve with the original guides though. i dont think that technique would work with a newly installed valve guide. im going to be going through a machine shop for my guide replacement instead of doing it myself. thanks for all the info.
     

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  15. ricktb

    ricktb Proven Member

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    I had my guides replaced by a machine shop for about $6-8 bucks a piece. After I found the valve no longer contacted the seat all the way around. Tried to use valve grinding compound to close the seal , but after 5 minutes I realized it would either take way to long, or may wear the valves down way to much. Took it back the the shop and they finished off the valve job for me...

    total expense $450CAN (not incl parts) for that I got:

    pressure test
    mag flux test for cracks
    hot tanked
    guides replaced
    seats cut
    deck shaved
    valve stem cut to length to bring everything back to factory specs
    reassembly of valves, seals, springs, retainers, and keepers

    well worth the money! It runs like new
     

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  16. BogusSVO

    BogusSVO Proven Member

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    A couple points are not right.

    First, you can not magaflux an aluminium head, the magnetic field will not pass through.

    Only ferrous metals can be magnafluxed, cast iron and steel

    You pressure test an aluminium head for crack, either submerged tank or a soap water solution to look for bubbles.

    Also having the head milled has zero to do with valve tip height on a OHC style engine.

    Grinding the valve tip is all that needs done, also you missed that it also increases valve spring installed height, so an extra shim is normally added under the factory spring seat.
     
  17. DSM's 4 life

    DSM's 4 life Proven Member

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    I just got my head back from the machine shop they charged me 438.45

    I droped my bare head off to have the guides replaced they decked my head and ground the valves i gave them. Today i lapped and the valves and installed by stem seals i was using a socket and an extention and pressing them on by hand one or two gave me some troubble so i used a ball peen hammer and bareley tapped it and my guide moved???? you guy are talking about liquid freezing parts for clearence and I barley gave it force and moved my guide im concerned i just paid all this money and its going to give me issues
     

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  18. boostdawd

    boostdawd Supporting Member

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    What all did they do for over 400? I recently got my head refreshed also. Replaced all valve guides, valve stem seals, minor port work, fully cleaned and decked for 280.00
     

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  19. miliman13

    miliman13 Proven Member

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    price don't add up. ^
     

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  20. bastarddsm

    bastarddsm Proven Member

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    If your guide moved, it is likely loose and will fall out
     

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  21. donniekak

    donniekak DSM Wiseman

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    They probably took some aluminum out with the old guides, then just installed std guides.

    Good head work is expensive because it takes time. I get volume discounts and it's cheaper for me to get a block bored, honed, decked, and a crank balanced than get guides and valves installed in a head.
     

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  22. DSM's 4 life

    DSM's 4 life Proven Member

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    Heres my recipt
     

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  23. DSM's 4 life

    DSM's 4 life Proven Member

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    Also one of the guides holes in the head were damaged by them
     

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  24. miliman13

    miliman13 Proven Member

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    It's difficult to say what " is" the price of machine work. But for me, in my area based off the average of 3 shops that is costly labor.
    Not to mention the charge for "valve seals " is double what they are sold for on our vendors site.

    The rest does seem right.

    What do you plan on doing? You already paid them for the work so I would hope they cover it.
     

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  25. DSM's 4 life

    DSM's 4 life Proven Member

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    Im not to sure what i can do? Do i ask them to put oversize guides in free of charge?
     

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