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  1. #1
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    Default Timing marks 1996 Mercruiser 5.7

    I am trying to time my 1996 Mercruiser 5.7 and am having a hard time understanding the timing markson this engine. Can some one advise? I know that 8degrees BTDS is correct. I just can't read the timing marks Thanks

  2. #2
    Honorary Moderator Emeritus Don S's Avatar
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    Default Re: Timing marks 1996 Mercruiser 5.7

    Below is a drawing of how the timing marks are setup. Do you know if you have a Thunderbolt IV or Thunderbolt V ignitions system. The method of timing is different for the TBV ignition from the standard TB IV ignition.
    Don S.


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  3. #3
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    Default Re: Timing marks 1996 Mercruiser 5.7

    I have a Thunderbolt IV. My timing marks do not look like that though. On the cover it almost looks like a U with no marks but a line in the middle. If I had to guess I would say the line is TDC and the U points mark 8 degrees before and after if this makes any sense to you.Thanks

  4. #4
    Honorary Moderator Emeritus Don S's Avatar
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    Default Re: Timing marks 1996 Mercruiser 5.7

    Merc puts a lot of paint on them, and sometimes you can't see any numbers.The deepest notch is always 0° or TDCThe high peaks (Points toward belt) are 4° apartCan you post a picture of your setup if it's different?
    Don S.


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  5. #5
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    Default Re: Timing marks 1996 Mercruiser 5.7

    Thanks Don,I will try to take a digital image of the time marks tomorrow. Is there any trick to attaching an image to response?

  6. #6
    Honorary Moderator Emeritus Don S's Avatar
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    Default Re: Timing marks 1996 Mercruiser 5.7

    Look at this thread for instructions given by Dunruna, if that doesn't work for you, let me know and you can email the picture to me. http://www.iboats.com/cgi-bin/ubb/ul...;f=24;t=011127
    Don S.


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  7. #7
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    Default Re: Timing marks 1996 Mercruiser 5.7

    Hello Don,Lets see if this image comes through. [IMG]

  8. #8
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    Default Re: Timing marks 1996 Mercruiser 5.7

    Don, Please send me your e-mail so I can forward image to you.my e-mail is:keastman@socal.rr.com

  9. #9
    Honorary Moderator Emeritus Don S's Avatar
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    Default Re: Timing marks 1996 Mercruiser 5.7

    You got mail.
    Don S.


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  10. #10
    Honorary Moderator Emeritus Don S's Avatar
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    Default Re: Timing marks 1996 Mercruiser 5.7

    While all the information I posted earlier about your timing marks is correct for a 96, 5.7L engine. HOWEVER, you seem to have a 2001 or newer engine in your boat.That "plastic" timing chain cover is only used on the newer blocks and can not be used on older ones. So obviously you have a newer engine than you thought. But back to the timing.There is a notch in your vibration dampner that is at 0° or TDC. What you need is a decal to put on the vibration dampner. Mercruiser has one, and the part number is 37-864360.If I was you, I would order a couple of them so you have one on hand, that or when you put it on, scribe a mark in the vibration dampner and mark it so it can't go away. Use the decal to locate the proper mark for your engine.Just be carefull and put the decal the proper direction. See my earlier drawing. Your photo for others to see (smaller of course)
    Don S.


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  11. #11
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    Default Re: Timing marks 1996 Mercruiser 5.7

    Thank you Don, for your research and your help. I bought the boat used and did not know that there was anewer engine.Thanks

  12. #12
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    Default Re: Timing marks 1996 Mercruiser 5.7

    Don,How could I confirm the newer block besides the timing cover, would the serial number on the block identify? I am interested because I know I have the pre votec heads so possibly some one put a short block, which might then have the newer hardened rods and pistons which might make it more practical to consider putting on the vortec heads and converting to a 4 barrel carb in place of the 2 barrel.What do you think?

  13. #13
    Honorary Moderator Emeritus Don S's Avatar
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    Default Re: Timing marks 1996 Mercruiser 5.7

    Don S.


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  14. #14
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    Default Re: Timing marks 1996 Mercruiser 5.7

    I believe the plastic/composite timing cover started in '97, on all sbc's, not just vortec. A slightly changed water pump to clear the new cover, too. Also thought Thunderbolt V started in '95. If the block has been replaced, short of a teardown, you can't tell what was done or what parts are in there.

  15. #15
    Honorary Moderator Emeritus Don S's Avatar
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    Default Re: Timing marks 1996 Mercruiser 5.7

    I thought it did to, but look at the drawings from the parts books below. Not sure what engine he has, but the 97 service manual shows the metal timing mark, so that is what I gave him a picture of. When he sent me the photo, I only found it in the manual for the 2001 and newer engine. Understand now that I was looking for timing information, not front cover composition.Here is what I found when I went looking for the composite front cover in the parts book.99 to 2001 was this one, with no pictures of the timing mark in the 98 to 2001 service manual. Then in the 2001 parts manual I found this picture, and the 2001 and newer manual showed the decal and composite cover on the engine that I posted. I also found this in the 98 to 01 service manual Thus I gave him that information. I have now looked some more and it looks like the composite cover was used from 98 and up, but the metal cover was also used.Strange to say the least.
    Don S.


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  16. #16
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    Default Re: Timing marks 1996 Mercruiser 5.7

    DonS I know where there is a carolina classic 26 with a pair or merc 5.7's that has each style cover and the engines were repowered as a pair. not sure how what or why they keep changing. all I do is fix them. have you ever wondered why, if the seal is replacable, you cannot reuse the composite cover? has big words right on it. do not reuse cover if removed. myself if I take it off I toss it just always wondered why.
    no tech questions by PM, they wont get answered.
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  17. #17
    Honorary Moderator Emeritus Don S's Avatar
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    Default Re: Timing marks 1996 Mercruiser 5.7

    I don't know either, and it makes me wonder why also.Good news is, I haven't seen any rusted through like the old ones did.
    Don S.


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  18. #18
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    Default Re: Timing marks 1996 Mercruiser 5.7

    Don,I just looked up the parts list and found the same thing as you. Nothing under '97, but in '98 to 2001. Hmmm. I did find info in Dennis Moore's book on SBC performance, that it was in '97. I have a '97, but not 100% sure what style I have. Coming up on its first spring tune-up and timing. It is 2 hours away, or I'd check it right now. From a picture, blown up, I think I see one of the new cover type bolts. Anyway, I'll know sometime this month.I guess all we can say is, T4 and the new timing cover probably didn't come on the original mercruiser engine, from the factory.

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