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Onan question


mikeb

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I'm comfortable with motorcycle and auto engines, but I'm new to Powrmax's and Onan engines. I have a quick question maybe some of you Onan experts can help me with. The Powrmax service manual indicates the spark plugs fire simultaneously, but when setting the valve clearances, you rotate the crank 1 rev to set the other cylinder. If I understand this right, the coil fires both plugs on each revolution at the same time, but only one plug per revolution does any work as the other fires in between the exhaust and intake strokes. Correct assumption? This only matters to me because I'm trying to use an old (non-inductive) dwell/tach meter to determine engine speed on the Onan. If the Onan coil fires once every revolution, then it's running 4 times faster than the V8 scale on the meter says it is: ie, 300 rpm on the V8 scale is actually 1200 "Onan" rpm. Thanks again, you folks are a great help. Mike Bennett Fresno, CA
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A 4 stroke engine only turns 2 revolutions on the crank. You are correct about it fireing on the dead stroke of one cyl. and on the power stroke of the opposite. But with only 2 revolutions, multiply it by 2.
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You are correct multiply by 4. That is one engine the non-inductive meter should work on, if it were an inductive meter you would divide by 2.
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Thanks for the help, always nice to double check my thought process on something new. mike
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