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  1. #1

    Question Mercruiser 3.0 L upgrade to Delco EST


    want to upgrade a Mercruiser 3.0L from conventional ignition to a Delco EST. All the hardeware stuff of Delco EST is completely in place. Unfortunately I actually do not have any manuals.
    Of course I experienced all the "problems" related - so the (+/-) confusion with the shift-break-switch, the resistor power cable, the strange "programming behaviour" of the Delco EST and finally the max. ignition angle of about only 20 deg assuming an adjust to have a smooth idle.
    However, with the old and meanwhile defective (brokeen springs etc.) breaker points ignition it was always possible to adjust the ignition system to be fine; good idle and full power at the end of rpm-range. With Delco EST I have a significant decrease of max engine power and boat speed.
    I read some posts here concerning this theme - now:
    The manual 13covr2.pdf (http://www.boatfix.com/merc/Servmanl/13/13covr2.pdf) - some threads point to - only contains the table of contents, the rest is missing. Are there any other known locations for the complete document? Any other docs in this case concerned are welcome.
    And is it possible to get a circuit diagram - not only a wiring plan for the outer wiring - for Delco EST? I even don't know whether or not Delco EST is built in discrete or computerized electronic ... That's it ...

    Thanks, Ron the German .

  2. #2
    Join Date
    Jun 2009
    New Plymouth,Taranaki,New Zealand

    Default Re: Mercruiser 3.0 L upgrade to Delco EST

    The only things I did when I fitted a electronic Delco dissy,as against the points condenser type on my 120hp chev/GM,was to have the Ignition feed wire activate a relay,so when key goes on,I get a direct feed of 12v,from the starter solenoid.works very well.plus set the ignition timing by ear,advance it up till engine surges a bit then drop it back a bit.Because of our low octane rating,timing marks dont reallyfactor into tuning our vehicles.Plus,on the Holden motors,same as the 3.0 litre GM chev,weve found the harmonic balancer outer hub moves on the rubber,so timing marks are inaccurate.Had to tune them by ear as well

  3. #3

    Default Re: Mercruiser 3.0 L upgrade to Delco EST

    Thank you budgie, it's okay, when you are satisfied with your settings made by experience and ear. I also achieve a pretty good behaviour of the engine at all. And there is no remarkable difference if I adjust it by ear or by measuring instruments - using Delco EST as given.

    The point is that the old ignition worked better, it enabled the engine to run about 4600 rpm at full power. With Delco EST I only reach about 4100 rpm.
    I'm unsure about the adjusting procedure of Delco EST - where should be the difference between 1 degree with jumper and 12 degees without jumper. I do not have the opportunity to strech the range of the ignition angle in a second adjusting step. That's why I'd like to have a detailled circuit diagram to see, what's going on there. May be any modification is possible, but please not with blind eyes.

    And yes, when I preset the Delco EST to higher angles, full power as in former times will be achieved but with unreasonable idle state - resulting in bad bad engine start, it may even be impossible to start the engine. And you know - when you are at sea, everything should work best and reliable.

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