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mech123

onan rpms

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mech123

im trying to set top no load on my powermax... I used 2 different tacs, tiny tacs and read 4950 or so.... engine does not sound like its running that fast... I used a vibr tac and reading is about 2700 rpms.... which reading do I use??? does the 12 volt coil and point interrupt the electrical tac readings????

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quote:Originally posted by 720nut

Hey Bob where do you get one of those, looks to be pretty neatdOd


id="quote">
id="quote">I don't have the Tiny Tach but the $18- variety they say good for 36000 hours or 4 years. Mine is still ticking after three years, E-bay or Amazon.

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mech123

I was talking with a guy about this rpms issue. He use an rpm tac on his model Rc airplanes. Put a piece of tape on 1prop blade and use the tac. This read the true crankshaft rpm. He said the kit is about 25$ at a hobby shop...another old time car mechanic said his tac has to be set per number of cylinders on vehicle

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Kenh

The "RC" tach, if it is like mine, is an optical tach. It reads the contrast of light and dark. You will need two pieces of tape to get a true reading. I would suggest wrapping the crank with black tape and placing two white stripes on the tape and a bright light for the best reading. It's possible it MIGHT read the keyway but I doubt it would. One piece of tape will require doubling the reading. Mine is very accurate. The vibrtach is a good piece of equipment. That should be as accurate as you need.

Ken

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