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jhemp3
#1 Posted : Sunday, February 06, 2011 4:42:28 AM(UTC)
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Where do you point an optical tachometer to get an actual engine RPM when setting idle speed? I'm thinking at the flywheel through the timing opening but really don't know.
Thanks,
Jim
Jim Hemphill
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ComputerJoe
#2 Posted : Sunday, February 06, 2011 4:48:04 AM(UTC)
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Uh yeh.
And it really helps to use a piece of chalk to make the pointer and degree lines more readable as well.
A dark garage, or night time helps as well if the tach strobe isn't very bright.
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jhemp3
#3 Posted : Sunday, February 06, 2011 4:55:59 AM(UTC)
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Thanks, Joe
Jim Hemphill
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Berthed MM 207 Tennessee River, Picwick State Park Marina
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dougrose
#4 Posted : Monday, February 07, 2011 12:12:22 AM(UTC)
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I used the damper on the front of the engine because I couldn't see the flywheel. I taped around the outside with a strip of black tape, then put a thin strip of white tape on. Now the tach light works very well.


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jhemp3
#5 Posted : Monday, February 07, 2011 1:19:56 AM(UTC)
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I tried that also, without tape, and received readings a little different from the flywheel? I guess I was getting an invalid reading without a the optical clarity of having tape on the area. Don't know if "interference" of some sort from the other pullys could be a factor. Then "overthought" different circumfrences and the such...
Jim Hemphill
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'87 32' FBS, USCG Certification #1057921
Berthed MM 207 Tennessee River, Picwick State Park Marina
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Rick100
#6 Posted : Tuesday, February 08, 2011 2:29:42 AM(UTC)
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jhemp3 wrote:
Where do you point an optical tachometer to get an actual engine RPM when setting idle speed? I'm thinking at the flywheel through the timing opening but really don't know.
Thanks,
Jim


If what you have is a optical tach you can point it at anything that rotates for an rpm measurement. In the case of our boat engines the flywheel or the crankshaft damper in the front works just fine. All the optical tachs I have used require a strip of reflective tape on the thing you want to check the speed of. A timing light needs nothing to work except the signal from # 1 plug but a white mark on the damper or flywheel makes it easier to see. Rick
When I die I hope my wife sells my stuff for more than I told her I paid for it.
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