454 Valve Lash Adjustment

Discussion in 'Gas Engines/Drives/Transmissions/Props' started by dcogaming, Jul 18, 2012.

  1. dcogaming

    dcogaming New Member

    15
    Oct 20, 2010
    Lower Niagara River - Lake Ontario
    340 Sundancer 1987
    454 Mercruisers
    Hi everyone,

    I have a 1987 340 SDA. It has the twin 454s (340 MIE). I had to do the head gaskets on the starboard engine and was hoping for some advice on adjusting the valve lash. I would normally do this warmed and running on my street motor but with the exhaust set-up on the Mercruiser this is far from easy to do. So I was hoping someone could lend some advice on the cold engine off procedure. :smt100
     
  2. rondds

    rondds Well-Known Member SILVER Sponsor

    Oct 3, 2006
    Jersey Shore
    2001 380DA
    Merc 8.1s (2008)...Hurth ZF 63 V-drives...WB 7.0 BCGD (2013), Garmin 8208 & 740 MFDs, GMR 24xHD dome
    DCO
    Take a look at this thread. I just went through the same issue. and found that it is possible to remove the covers (I do not have exhaust risers, only elbows).
    http://clubsearay.com/showthread.php/50132-Valve-Cover-Removal-on-454-7-4L

    This is the procedure for cold and hot (running) straight out of the Merc Manual for my 7.4MIE Gen IV with hydraulic lifters. Either way (hot or cold) works perfectly but don't make the mistake I did and forget to adjust one!

    [​IMG]

    [​IMG]
     
  3. Bt Doctur

    Bt Doctur Well-Known Member

    Aug 21, 2010
    New Jersey
    Ex SRV 240 Weekender twin
    in between
    Much better off doing each cylinder, rotate motor untill the intake valve for that cylinder opens and then closes, now your on compression both valves closed. tighten nut untill all slack is gone, ( cant spin rod with fingers), then go 3/4 more.
    valve sequence E,I,I,E,E,I,I,E
    http://boatinfo.no/lib/library.html
     
    Last edited: Jul 18, 2012
  4. dcogaming

    dcogaming New Member

    15
    Oct 20, 2010
    Lower Niagara River - Lake Ontario
    340 Sundancer 1987
    454 Mercruisers
    Awesome Ron ty for your help


     
  5. rondds

    rondds Well-Known Member SILVER Sponsor

    Oct 3, 2006
    Jersey Shore
    2001 380DA
    Merc 8.1s (2008)...Hurth ZF 63 V-drives...WB 7.0 BCGD (2013), Garmin 8208 & 740 MFDs, GMR 24xHD dome
    DCO, it's straight from "The Bible." I've done it now three times and if you do it right, you'll be ok. Sounds like you are no stranger to this type of thing so you won't make the stupid rookie mistake I did.
     
  6. Happy Hour IV

    Happy Hour IV New Member

    294
    Nov 22, 2009
    California
    340 Dancer 1988
    454 Merc BW V drives
    I did mine hot. I replaced the two studs/nuts near the riser on the valve cover with allen socket bolts. They are now very easy to remove with
    a ball type allen wrench. Just like a car there is very little oil splash when running at idle.
     
  7. rondds

    rondds Well-Known Member SILVER Sponsor

    Oct 3, 2006
    Jersey Shore
    2001 380DA
    Merc 8.1s (2008)...Hurth ZF 63 V-drives...WB 7.0 BCGD (2013), Garmin 8208 & 740 MFDs, GMR 24xHD dome
    Three's a fair amount of debate about how many turns to go on a big block after lash is removed. I've heard 1/2, 3/4, and full (Merc Manual). I did a full turn using the cold method.

    When we went back in to do the hot, we checked all 8 valves by backing off til lash noise and then retightening according to the manual (with the engine running). When backing off on each nut, rattling started right at one turn. Sort of proves that a cold adjust is just as reliable as a running adjust.
     
  8. Saverio

    Saverio Member

    999
    Aug 31, 2010
    Long island new york
    1995 330 DA
    Twin 454 Webber Carbs
    V drives
    Fresh water cooled
    Looking for some help. I'm down on power on Port did compresson test found 160 across except 2 at 130. I want to pull heads and send them out.

    all my manual says on gen V is to set rockers at 45lbs torque. is that true no vavle lash adjustment???
     
  9. rondds

    rondds Well-Known Member SILVER Sponsor

    Oct 3, 2006
    Jersey Shore
    2001 380DA
    Merc 8.1s (2008)...Hurth ZF 63 V-drives...WB 7.0 BCGD (2013), Garmin 8208 & 740 MFDs, GMR 24xHD dome
    I believe that Gen V that is correct. My post (above yours) from 2012 describes the Gen IV process. Gen V is simpler.
     
  10. Saverio

    Saverio Member

    999
    Aug 31, 2010
    Long island new york
    1995 330 DA
    Twin 454 Webber Carbs
    V drives
    Fresh water cooled
    wow I kept reading the manual thinking im missing something so put it all together and just torque the rockers down and done??? wow
     
  11. d-reed

    d-reed New Member

    12
    Oct 23, 2018
    Western Ma.
    1996 Sundancer 250 DA
    Gen 6 454 carb Bravo 1
    I have a Gen 6 and the rockers are bolted down. If yours have studs with nuts you need to adjust them. 0 lash then 1 turn. cold engine. If my memory is correct, flat tappet cam is adjustable and roller cam is not? You can go on You Tube, lots of vids on how to do it. You do not have to run the engine. It will start right up and have no noise or mess! You will impress your buddies too!
     
  12. rondds

    rondds Well-Known Member SILVER Sponsor

    Oct 3, 2006
    Jersey Shore
    2001 380DA
    Merc 8.1s (2008)...Hurth ZF 63 V-drives...WB 7.0 BCGD (2013), Garmin 8208 & 740 MFDs, GMR 24xHD dome
    Gen 5 is a torque spec. Follow what your manual says.
     

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