Engine RPM's

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Hi all,   I am trying to tune up an old short hood. How do you check what RPM's you are running?Is there a gizmo or technique that anyone knows how to get an accuratenumber so I can get it in specs?
Reply:I have a harbor freight photo tach I use on small engines. I checked it against a 1750 rpm elec motor and it was dead on.  About $60 IIRC.                                                                MikeOl' Stonebreaker  "Experience is the name everyone gives to their mistakes"Hobart G-213 portableMiller 175 migMiller thunderbolt ac/dc stick Victor O/A setupMakita chop saw
Reply:I use a laser RPM gauge with reflective tape on the end of the exciter, but above all I check the voltage at the 120 volt plug and the welding lead studs.Don’t pay any attention to meI’m just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
Reply:OK, I've been looking into those, but I am wondering also if anyone has used something like one of these multimeters to find rpm's.  It actually has a setting for rpm's and breaks it down into 4,5,6,8 cylinder motors. And then you can use it as a regular voltage meter and all that. https://www.napaonline.com/Catalog/C...884_0282460874
Reply:Originally Posted by mla2ofusI have a harbor freight photo tach I use on small engines. I checked it against a 1750 rpm elec motor and it was dead on. About $60 IIRCMike
Reply:multimeter. use the HZ setting. measure the 115 volt receptacle and set for 61 to 61 HZ under NO load. Or get  kill-o-watt plug in device at the home center. It plugs in to the 115 volt receptacle and reads Hz and  watts  if you have some thing plugged in to it.
Reply:Originally Posted by ccawgcmultimeter. use the HZ setting. measure the 115 volt receptacle and set for 61 to 61 HZ under NO load. Or get  kill-o-watt plug in device at the home center. It plugs in to the 115 volt receptacle and reads Hz and  watts  if you have some thing plugged in to it.
Reply:I just bought a digital laser tachometer on ebay for I think $19.  The exact same tach is sold for up to $70, so just look at the pictures and buy the cheapest.  But check the location first - the very cheapest shipped straight from Hong Kong!  I think mine came from New York - the seller was "hi-pc" or something like that.  He'd sold like 400 of them with 100 percent feedback.  Shipping was very fast. Like CEP was saying, just tape a 1/2" square piece of the included reflective tape on it, and go to town.  I put my tape on the crank pulley.  It works well on diesels also.  Very accurate and repeatable.
Reply:Thanks for the ideas fellas.I'll get one of those laser tachs then. Seems like the cheapest most accurate method. If I place the reflective tape on the exciter shaft end, does it rotate at the same ratio as the motoror is it geared up or down? I would try for the crank pulley, but I don't want to have to drain and remove the radiator to get a straight shot on it.
Reply:sorry about that. Most of the engine drive welders I get to work on all are ac power.Don't get to work on the Dc aux power welders.
Reply:Don't know if you can still buy them, but an anolog elec clock w/ second hand works good for setting Hz to 60. Just plug it in to welder/gen and check the clocks 60 sec against your wrist watch. 61 or 62 sec clock time against the wrist watch's 60 sec would be 61 or 62 Hz. Someone correct me if I'm wrong.                                                    MikeOl' Stonebreaker  "Experience is the name everyone gives to their mistakes"Hobart G-213 portableMiller 175 migMiller thunderbolt ac/dc stick Victor O/A setupMakita chop saw
Reply:Originally Posted by kamotzIf I place the reflective tape on the exciter shaft end, does it rotate at the same ratio as the motor or is it geared up or down?