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Valve adjustment issues 79 308

Discussion in 'Technical Q&A' started by dan the man, Mar 29, 2005.

  1. dan the man

    dan the man Karting

    Nov 5, 2003
    146
    Alabama
    Full Name:
    Daniel
    I have recently had a set of heads reworked with new Valves. the seats looked good, and the guides were fine.


    I am now trying to adjust the valves. both of the Exhaust cams (and one of the intakes) are basically at 0 clearence or less. my valve pucks are averaging around .160 inch (4.06 mm).

    I need a bunch of Pucks ( mainly between 3.4 mm and 3.8 mm) so that I can adjust the valves. If anyone has a bunch of pucks that they can let me use to adjust the valves, I will gladly buy the pucks that I use, or replace them.


    Thank you

    Dan
     
  2. Gary48

    Gary48 Guest

    Dec 30, 2003
    940
    Dan, here's an alternative to adjusting valves with the heads off! Keep your stock (pucks) but dry assemble the buckets and cams without springs and retainers, then push a valve into the head and measure the clearance between the cam base circle and the puck. This will usually be tighter than needed when grinding seats and replacing valves. It is then simple to grind the valve tips on a valve machine to get the nesessary clearance. I am doing this currently on my 246. Good wrenching!

    Gary
     
  3. yelcab

    yelcab F1 Veteran
    Consultant

    Nov 29, 2001
    9,236
    San Carlos, CA
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    Mitchell Le
    2-valve engine valve shims (you called pucks) are volvo shims. Buy them from your local volvo dealer. Make a list of what size you need, go down there and pick them up at $6-$7 a piece.
     
  4. dan the man

    dan the man Karting

    Nov 5, 2003
    146
    Alabama
    Full Name:
    Daniel
    What year Volvo's and engines fit?
     
  5. Steve Magnusson

    Steve Magnusson F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    18,404
    Texas
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    Steve Magnusson
    Just go by the outer diameter (if you can't get an exact model cross-reference) -- 2-valve 308 shims are 33mm diameter, 4-valve 308 shims are 29mm diameter.
    (My notes also show that Fiat used the 33mm size in some applications.)
     
  6. ferrarifixer

    ferrarifixer F1 Veteran
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    Jul 22, 2003
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    Phil Hughes
    You should NOT grind the valve tips at all. This is VERY bad engineering practice, and can cause medium to long term unnecessary expense.

    The tips are hardened, and you'll soften them by grinding.

    Also, you may leave a sharp edge which can score the guide and damage the seal while installing.

    Also, if you remove enough, the bucket can touch the spring retainer and you will drop a valve when the collets jump out.

    Also, the valves springs need to be at a certain fitted length, so if you are finding the clearance is too small, you may also find that the valves and seats are either worn or cut too deep, making the springs too long once fitted...and therfore weaker.

    Also, I find Australia quite expensive for parts... and shims from a local engineering supplier are about AUD $5, so about US $3-4. The shims are readily available and have hardened surfaces.

    Get a workshop manual, or get proper technical help to do this job. It is woefully false economy to short cut head work.
     
  7. Lawrence Coppari

    Lawrence Coppari Formula 3

    Apr 29, 2002
    1,861
    Kingsport, TN
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    Lawrence A. Coppari
    Never grind shims. They are only surface hardened. Surface is much harder than metal beneath surface. This comes from heat distribution during the process.
     
  8. F308 MAN

    F308 MAN F1 Rookie

    Jan 19, 2004
    2,907
    Isle of Man
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    Dave S
    Ferrari UK have the shims ... at around £2 (GBP) each.
    Click on "Sponsors", above, for their contact details.
    cheers, d
     
  9. fletch62

    fletch62 Formula Junior

    Mar 8, 2004
    333
    Fairhope, AL
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    Larry Fletcher
    I bought a complete set of shims in a case, 68 shims for about $120. You need to contact International Auto Parts and get a set of shims for a 124 Fiat. http://www.international-auto.com/
    Larry
     
  10. Gary48

    Gary48 Guest

    Dec 30, 2003
    940
    Dan, you may get conflicting information about what to do,but if you have changed to stainless valves, grinding the tips is very o.k.; This is a no wear zone period, strickly a push deal with no problems associated with this procedure. This is done by many top engine builders on overhead cam motors of all types. Waste your money on a plethera of different shims and you won't use half of them and you won't get accurate lash either for your effort. Consider the fact that your lobe which has already mated to your stock (puck) will again have to remate to the new (puck) with sometimes more wear to the cam lobe. This is why it is highly advisable to keep the same puck with the lobe it is mated too. This is sound advise and very good engineering principle

    Best regards

    Gary
     
  11. pma1010

    pma1010 F1 Rookie

    Jul 21, 2002
    2,558
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    Gary
    I am not an engineer. I did talk to Dema Elgin (who is) about the issue of replacing shims. He sees many examples of lobe wear from shims NOT being replaced.

    One data point. Appears to be 180 degrees different from your view.
    Philip
     
  12. ferrarifixer

    ferrarifixer F1 Veteran
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    Jul 22, 2003
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    Sorry Gary, but have to absolutely disagree with you.

    New shims save wear and tear on cam lobes for a start, not increase it... and valve tips will soften, and then mushroom out if ground down and not re -heat treated afterwards... never mind the installation problems I already mentioned.

    If, later on, you then need to remove the valves, a mushroomed out tip will rip up the seal and damage the guide for sure... unless you try to grind the edge off before you slide it out...which is just a pr1ck of a job and totally unnecessary.

    I've just fixed a 308 for this EXACT reason, and it had stainless valves fitted, and it's installed valve springs were reduced to below 50lbs seat pressure due to worn/cut valve seats and ground tips.

    So, sorry Gary, but tip grinding is something our Aussie Bush mechanics might do... but these guys also use tree bark for brake pads.
     
  13. Gary48

    Gary48 Guest

    Dec 30, 2003
    940
    Dan, I am sure you will hear some more from our mate from Oz. My point is you can safely grind stainless valve tips, the reason is that these tips are inductioned hardened. This hardening process goes in from the tip at least 1/8 of an inch. the amount you will have to remove at most would be .010, well within any hardening. After grinding the tip you then grind a small 45 degree bevel at tip end and you've got it. They will not hammer out period. Think about it you have a hardened tip and its setting on the underside of a hardened bucket, how the heck will it hammer out? There is no clearance to speak of. By the way this is all done on a valve grinder in a precision and small way. If you grind off of the tips you will not change the dimention of the valve keeper to the spring seat as was suggested, the only way that would change would be to grind the valves or seats. I have offered this method as an alternative and I hope it helps you or anyone else interested.

    Gary
     
  14. ferrarifixer

    ferrarifixer F1 Veteran
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    Jul 22, 2003
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    I'm not saying grinding the tips will change the valve retention dimensions... but the REASON for a reduced clearance should be checked... and it is usually due to seat/valve wear. So it is far better to fix the cause, NOT the symptom.

    Also, especially with a 246.. which has large diameter, heavy valves.. the spring pressure is even more important.

    Also, with 246, don't waste your time re-fitting single collet ring valves and collets. More often than not the collet is, or will wear, and there is a simple up grade to use a double ring collet.

    The workshop manual for this whole procedure is very good and informative, it really should be followed as closely as is possible.

    Dont be defensive Gary. I'm not saying you're a lousy person/parent or you've got an ugly wife, I just think your advice is only to be used in dire emergencies at best. It's an option for sure, but it is not correct procedure.
     
  15. Gary48

    Gary48 Guest

    Dec 30, 2003
    940
    ferrarifixer, don't come off as the know all to end all, a little help for our buddy Dan is whats important here. Maybe you could learn a little from your shadetree bush mates, bark and all. By the way who told you about my wife

    Best of regards

    Gary
     
  16. ferrarifixer

    ferrarifixer F1 Veteran
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    Jul 22, 2003
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    If I knew it all I would be on a yacht cruising the world. I only know enough to be a mechanic living in a rented house driving a beaten up old car!

    I don't know what your occupation is, but I would bet you are certainly better at it than me...

    ...and I will be cocky enough to say that I am probably more experienced and better placed to give advice on this.

    As for your wife..... we dont adjust valve clearances while our tools are in the sump... do we!
     
  17. arnup

    arnup Rookie

    Mar 31, 2005
    24
    sydney
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    kevin
     
  18. Gary48

    Gary48 Guest

    Dec 30, 2003
    940
    Ah! now thats the spirit, I was looking to push your buttons and you fell hook line and sinker, at least your not a bloody poof! but you seem a mite uptight, maybe a good piss-up is in order. The next time I'm in Oz I'll get in touch and I'll buy you a couple of rounds and we'll talk cars. Thanks for the banter and the advice even if it isn't fact just opinion. Just kidding, don't get excited.

    Best of regards

    Gary
     
  19. Rifledriver

    Rifledriver Two Time F1 World Champ

    Apr 29, 2004
    25,491
    Austin TX
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    Brian Crall
     
  20. arnup

    arnup Rookie

    Mar 31, 2005
    24
    sydney
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    kevin
    Valve tips will not soften, and then mushroom out! The 308 with the low seat pressure will be the cause difficulty of removing valves... not the tipping you are incorrect
     
  21. arnup

    arnup Rookie

    Mar 31, 2005
    24
    sydney
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    kevin
     
  22. Gary48

    Gary48 Guest

    Dec 30, 2003
    940
    Thanks guys, I thought I was all alone out there. Here again the Ferrari myth that its a super delicate exotic, mystically forged from unobtainium in darkened shops is debunked. That Ferrari is so different that it transends all other engine practices and metalurgy is also a myth that has been highly honed and carefully nurtured by the leagues of the uninformed. I for one value it for its uniqueness and highly value the application of proven techniques to improve and simplify the Ferrari art form without the drama of rigid by the book rules. Lets have fun advancing the art form and improving the species. A sincere note from someone with an engineering and metalurgy background

    Gary
     
  23. ferrarifixer

    ferrarifixer F1 Veteran
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    Jul 22, 2003
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    Sorry kevin.

    I don't have any idea what i'm talking about, and the dozens of times I've had to repair engines that have been (far too recently) valve tipped is just a figment of my imagination. I'd guess I've done about 30 cylinder head overhauls for this reason.... or did I just dream it.

    In the mean time, I'll keep scouring pages of workshop manuals until I find it written as correct procedure, and I'll write to all the shim manufacturers to tell them their services are no longer required.

    Are you happy now.......?

    Tipping valves is done once, during manufacture to set the correct protrusion above the collet ring and overall length. It is done either to within the hardening already present, or it is re-heat treated after being tipped.

    To repeatedly tip them to set clearance is just a short cut that'll bite you in the end. There are many short cuts you can take on these cars, and this is one I would avoid.. even on my own car where I may be happy to take risks elsewhere..
     
  24. Ferrari_tech

    Ferrari_tech Formula 3

    Jul 28, 2003
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    Malcolm W
    #24 Ferrari_tech, Apr 1, 2005
    Last edited by a moderator: Sep 7, 2017
    Just my 2 cents worth - I have to say that "tipping" valves is not common practice in our workshops, certainly not done to achieve the correct valve clearance. Not only is it bad mechanical practice, but will change the dimentions between the valve tip and the theoretical centre of the camshaft.
    Image Unavailable, Please Login
     
  25. ferrarifixer

    ferrarifixer F1 Veteran
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    Jul 22, 2003
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    Phil Hughes
    Yeah, right. What would you or the author of that picture know about it.. eh...?

    Thanks Malcolm, A picture says a thousand words.

    You will see that there is a half mm tolerance for valve height. Thats '020 in old money.

    Can you post/scan the picture that shows installed valve spring heights too....??

    Just to help those interested understand even more...
     

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