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308 QV cam spec

Discussion in 'Technical Q&A' started by pad, Jul 10, 2006.

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  1. pad

    pad Formula 3

    Sep 30, 2004
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    Paul Delatush
    #1 pad, Jul 10, 2006
    Just want to verify that the exhaust cam timing for a 308 QV USA car is: open/close - 40*BBDC / 14*ADTC. Anyone sure on this?
     
  2. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    #2 Steve Magnusson, Jul 10, 2006
    The OM documentation on this seems unambiguous:

    US 308QV
    exhaust
    opens 50 deg BBDC
    closes 14 deg ATDC

    Where are you getting the "40 deg BBDC" spec?
     
  3. pad

    pad Formula 3

    Sep 30, 2004
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    #3 pad, Jul 10, 2006
    The OM that I have (PDF file) stated the exhaust timing is 50* / 10*. Awhile ago, I downloaded an article off the web stating the Euro 308 2V were 54* / 10, USA 308s 2V were 50* / 14*, however, the USA 308 QV were 40* / 14*. The article quoted Kieth Bluemels book. Is your OM the one that came with a USA QV?
     
  4. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    #4 Steve Magnusson, Jul 10, 2006
    Yes, the 260/83 (1983 model year US) and 307/84 (1984 and 1985 model years US) OMs both show the exhaust timing as 50*/14* (and the Euro OM shows 54*/10* -- indicating that the exh. camshaft lobe is the same and that it's just timed differently).

    What is the print number (XXX/YY) show in that .pdf OM? (should be on the last page or on the inside back cover)
     
  5. pad

    pad Formula 3

    Sep 30, 2004
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    #5 pad, Jul 10, 2006
    Printed in Italy cat. 248/02 n. 2500.

    Thanks for your help on this.

    The next question is which is of the 2 settings (Euro or US) would you set for performance. My car has EFI with near open exhaust fed by a 90mm throttle body attached to plenum that have double the stock volume.
     
  6. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    #6 Steve Magnusson, Jul 10, 2006
    That's kind of an odd print number (a low XXX number with a late YY number). The Euro 308QV OM is 248/82 so maybe they just renumbered the YY part to reflect the year (2002?) when they created the .pdf version?

    My guess is that the 50*/10* number is just a mistake that jumbles parts of the US and Euro specs together (there was a similar discussion about the same confusion on the 328 values a little while ago), but it should become self-evident when you do the actual set-up -- i.e., since you aren't changing the duration of the lobe you will only be able to achieve 50*/10* or 54*/10*&50*/14*, but not both (and same thing for the 40*/14* spec -- if it isn't physically achievable, you can safely conclude that it's just a printing mistake).

    I believe the Euro numbers will always give better performance, and the only downside on a stock US car would be it might be a little less healthy for the cat(s) and have slightly higher HC/CO emissions (i.e., if you are cat-less, there's no reason not to use the Euro values).
     
  7. pad

    pad Formula 3

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    #7 pad, Jul 10, 2006
    Steve,

    You're right, its 248/82 (poor quality reprint).

    Thanks for your help. I'll reset the exhaust cams to the Euro 54 /10 setting. Now to see if I can get these cams dial in before I grow too old to drive the car...
     
  8. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    #8 Steve Magnusson, Jul 10, 2006
    Well, that makes more sense (not changing the print number), but what page shows the 50*/10* spec?

    In the 248/82 OM .pdf available from the Owners Site, both page 10 and page 64 show the 54*/10* spec.
     
  9. pad

    pad Formula 3

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    #9 pad, Jul 10, 2006
    My mistake, it shows 54 /10. I think I need a rest....
     
  10. pad

    pad Formula 3

    Sep 30, 2004
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    #10 pad, Jul 11, 2006
    Finished dialing in the cams last night. Used the Euro specs. Interesting that the cam marks still line up within the cap marks, but not centered as they were before I used a degree wheel / dial indicator. One exhaust mark barely makes the "goal posts". In total, I put about 16 hours into this timing exercise.
     
  11. bill308

    bill308 Formula 3
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    #11 bill308, Jul 11, 2006
    Last time I did the cam timing, belts, and valve lash, I put a lot more than 16 hours into it several years ago. It takes time to do good work. I also determined TDC from the #1 piston, recorded shim thicknesses (averaged 4-measurements for each shim-some were not flat) and final clearances.

    Bill
     

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