preignition vs idle timing on 95 175hp oceanpro

angus63

angus63

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I read a post recently about a burned piston due to preignition (early timing)in a 3 yr old motor. I recently replaced powerhead and did the 10hr break-in. My wide open timing is 28° btdc and I verified with a light (still shaking from the experience). The manual calls for 4° atdc as the idle timing. In order to idle at 750 RPM, I have my idle between 0° and 2° atdc. Does the idle timing affect the operating timing in the lower rpms where preignition could be a problem???? Using 87 octane with QL78YC @ 0.030.
 
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Dhadley

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Re: preignition vs idle timing on 95 175hp oceanpro

If I read your post correctly, you have a 60 degree V6, right?
 
angus63

angus63

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Re: preignition vs idle timing on 95 175hp oceanpro

Yes I do. Used the "clips" on the timer arm to adjust idle timing (kind of a rack and tooth setup).
 
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Dhadley

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Re: preignition vs idle timing on 95 175hp oceanpro

Are you sure you want the total timing set at 28?
 
angus63

angus63

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Re: preignition vs idle timing on 95 175hp oceanpro

Sorry, too many numbers in my head today. The wot is set at 22° btdc. 28 is the feed rate of the machine i'm setting up at work.
 
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Dhadley

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Re: preignition vs idle timing on 95 175hp oceanpro

I believe the wot timing should be at 20 degrees. I'll have to check to verify. If it is 20 and you want to stay at 22, you might want to richen up the carbs at mid range and high speed. I would also go to a cooler plug. <br /><br />We don't normally worry too much about the idle timing within a couple of degrees. Whatever it takes to run properly. A lot depends on how low or high the motor is at rest on any given boat.<br /><br />Good luck!
 
angus63

angus63

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Re: preignition vs idle timing on 95 175hp oceanpro

Thanks for the info
 
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