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  1. AKJohne

    1997 5.7 LX knock sensor

    Yes sir
  2. AKJohne

    1997 5.7 LX knock sensor

    Thanks Chris, I suspected there was no simple easy answer, I was hoping someone on here had already done this. Next time I have the boat in the water and have the right conditions I will duplicate my experiment. My friend that helped today used his scope to capture the voltage drop when we...
  3. AKJohne

    1997 5.7 LX knock sensor

    Recently rebuilt the heads due to a tuliped intake valve, all back together and was verifying the knock sensor was functioning. Used a timing light and had the motor warm and running at ~ 1800 RPMS on the muffs. One guy watching the light and tapped on the block, sure enough you could see it...
  4. AKJohne

    Mercruiser 5.7 anti-siphon valve

    Do you have to have one? I dont on 97 5.7. Starts fine, sometimes several pumps shots are required if it hasn't run in awhile. Other wise non issue... just wondering?
  5. AKJohne

    5.7l mercruiser gen 1 alpha 1 to vortec head swap problem please help...

    Did you check the compression with the new heads? vortex heads have a smaller combustion chamber and often the pistons should be a reverse dome rather than dished. Suspect your compression is too high for the fuel you are using. I believe they make head spacers for this issue and not saying...
  6. AKJohne

    Burned valve or worse 1997 5.7 LX

    Motor is back together and running, valve's, timing & carb set, compressions all between 150 & 165. I think we are good for a another 100-500 hours, maybe more...! Been pondering this valve issue and nothing is pointing to detonation, lean or water I simply believe the valve was thin and got...
  7. AKJohne

    4.3LX acceleration opinions

    Do you have trim tabs? they can help getting on step by pushing the bow down.
  8. AKJohne

    Burned valve or worse 1997 5.7 LX

    Will see what they have, Probably..... HAHA....... by OEM I meant mercruiser/quicksilver, NAPA will not have them, IMO they are best for mannie/riser/elbow, probably not as critical at the mannie/head. I dont know what they are made of, looks like graphite impregnated...? In any case they sure...
  9. AKJohne

    Burned valve or worse 1997 5.7 LX

    The issue with ordering is the fact I am in Alaska and shipping times have become extended. I prefer to use OEM gaskets, I may see what NAPA has I.S. locally. I have a trip planned with our daughter and hoping to pull that off by the end of the month. Thanks for all the help/ideas.
  10. AKJohne

    Boat wiring

    Brake line, I am assuming this is steel and not a flexible rubber line that would go from axel to wheel?
  11. AKJohne

    Burned valve or worse 1997 5.7 LX

    I looked some and did not find one, will keep looking, paste link please if you know of another source. thanks Having trouble getting the exhaust head to manifold gaskets. Shipping, covid, who knows. I checked a local shop that does a lot of engine replacements and he said use RTV, he said that...
  12. AKJohne

    Burned valve or worse 1997 5.7 LX

    You have mentioned water several times, certainly its possible to cause this, however where was this coming from...? intake? typically cylinder pressure much higher than a 15 lb cap, so combustion gas usually goes to the cooling system and I saw no indication of that and in fact have a...
  13. AKJohne

    Burned valve or worse 1997 5.7 LX

    The 02 plate is NA, might have to make one. Picked up the heads yesterday, all new intakes as they were too thin to recut, guides and exhaust valves OK, new seals on the guides. Lilley will never get a definitive answer on why that valve failed, I dont think it was the fact I was running at 3800...
  14. AKJohne

    Burned valve or worse 1997 5.7 LX

    Good info on the o2 riser, I didn't know they existed for marine, thanks for posting/sharing that....!
  15. AKJohne

    Burned valve or worse 1997 5.7 LX

    Cleaning prepping parts and waiting to get the heads back. Thinking about the loose plug on the #3 cylinder, did the plug loosen after it got hot? or did the loose plug somehow contribute to the heat in that cylinder? all other plugs were tight, actually very tight.... I have hard time...
  16. AKJohne

    Burned valve or worse 1997 5.7 LX

    I dont think there was any water intrusion into the cylinder, I think the piston was washed with fuel when running the 75 miles back to the harbor. No compression at this time. Heads are at the machine shop for new parts as needed and getting refreshed. We made a plate and did a leak down test...
  17. AKJohne

    Burned valve or worse 1997 5.7 LX

    Gaskets & such, why is the top of the piston so clean?
  18. AKJohne

    Burned valve or worse 1997 5.7 LX

    I was curious about the piston as well, manifold, riser and elbow gaskets were still doing the job, I replaced the elbows this spring and use oem gaskets, actually pleased to see the exhaust manifold to head connection was in fine shape and the head gasket was not blown out either.
  19. AKJohne

    Burned valve or worse 1997 5.7 LX

    Have done both leak down and compression test b4 teardown. Will make a plate to check rings, I could wait until its back together, if I have rings issues would like to know now. Carb is a Weber 750, essentially a edlebrock 1410. Weber makes them for ed Secondaries start to open at 4200, start...
  20. AKJohne

    Burned valve or worse 1997 5.7 LX

    "Good head" and cylinder/piston
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