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wml52


Joined: Dec 2, 2015
Points: 1

Tecumseh HM-100 RPM's ???
Original Message   Dec 2, 2015 11:52 am
I'm new to this site and first time posting here so hello to all.

I have an 18 year old Tecumseh HM-100 10HP flat head engine that powers my 5000 watt self regulating portable generator. According to the manual the no load RPMs should be set to 3600 RPMs, I am assuming this is to give the correct 120 volt 60 Hz output. However when the generator is loaded to about half it's rated watts the engine RPM's drop along with the voltage and Hz. If I adjust the governor increasing the RPMs to give me approxitmatly 120 volts @ 60Hz when loaded I get around 3700 RPM when the load is removed.

So my question is this, will running the engine at 3700 PRM's with no load do any harm to the engine.  Any information would be appreciated.

Bill
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niper99


Location: London Ont
Joined: Dec 2, 2007
Points: 354

Re: Tecumseh HM-100 RPM's ???
Reply #1   Dec 3, 2015 1:48 am
only run engine at 3600 rpm.
RedOctobyr


Location: Lowell area, MA
Joined: Nov 5, 2011
Points: 282

Re: Tecumseh HM-100 RPM's ???
Reply #2   Dec 30, 2015 12:31 pm
For what it's worth, my Generac 5500XL RPMs also sag somewhat as a load is added. It has a Generac engine.

The Generac service manual says that with no AC load on the generator, the governor should be adjusted to give 61.5-63.5 Hz (3690-3810 RPM).

Before I adjusted it, it was about 60.5 Hz (per my Kill-A-Watt) with no load. Adding 3000W of load (a little over half of its capacity) brought it down to about 57 Hz.

I adjusted it to about 63.2 Hz. Applying the same load, the RPM sagged to 60.4 Hz.

I don't have other mechanical-governor generators to compare against (my EU2000i throttle is electronically controlled). But my Tecumseh OHV snowblower RPM also sags as a load is added, even before the throttle opens fully. I replaced the governor spring, and the sag was reduced, but is still present. So mechanical governors are not perfect, they don't seem to necessarily hold the exact unloaded RPM. So it seems reasonable to me to set the RPM a little higher than desired, with no load, if that's what the manual calls for.
This message was modified Dec 30, 2015 by RedOctobyr
bus708


Location: Maryland
Joined: Jul 24, 2010
Points: 321

Re: Tecumseh HM-100 RPM's ???
Reply #3   Jan 26, 2016 5:56 pm
The Tecumseh is a good engine, however they do not like high revs. Doing so can result in connecting rod failure.The 10 hp engine is notorious for that .
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