Tecumseh HM-100 RPM's ???

[wml52]

I'm new to this and first time posting here so hello to all.

I have an 18 year old Tecumseh HM-100 10HP 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

 

[Rivets]

With the no load RPM's set at 3600, what are your AC voltage and hertz readings? At what you call half load, what are your AC voltage and hertz readings? I am assuming you have measured the wattage of the units you are plugging in, which I should not do. If both readings are between 110-120 VAC and 55-60 Hertz you should not have any problems. If your voltage and hertz drop below 110 and 53 respectively, you are risking a chance of burning out your equipment.

 

[wml52]

OK, readjusted the RPM and the readings are as follows:

No load: 3650 RPM, 119.5 Volts @ 60.8Hz

1600 Watt resistive load: 3610 RPM, 122 volts @60.1Hz

3500 Watt resistive load: 3440 RPM, 110.6 volts @57.3Hz

Inductive load 1/2HP well pump: 3500 RPM, 113 volts @ 58.3Hz

The reason I asked about running at 3700 RPM no load was to compansate for voltage drop during heavy loading.

I should note that the RPM were measured using a Tiny-Tach so the RPM will not be that accurate due to the refresh rate of the tach but it all I have at the moment.

 

[Rivets]

If your heaviest lost is approx. 3500W, you should have no problems unless you are running units which have many electronic components. These units would be highly sensitive to voltage changes which occur with the older style generators such as your's. Most of the older generators were designed to power units such as electric motors heaters and lights, not computers, today's TV's, etc.

 

[aandpdan]

Most generators run around 3650 or so unloaded.

Your governor is just not sensitive enough to hold the RPM as you apply a load. It can be a worn spring or some play in the linkages - not unexpected on an 18 year old generator.

Check the linkage thoroughly.

 

[wml52]

The gen-set is only used to provide back-up power to essentials furnace, well pump, fridge, lights, coffee maker, microwave and electric water heater which is a managed load.

This gen-set has over 1400 hours on it so I agree with aandpdan I'm sure there is some wear in the governor and linkage assy which is why it fluctuates between 3650-3670 RPM. I'm sure the tolerances were much better when new but it's been so long I can't remember...lol

Although I'm pretty anal when it comes to maintenance, change the oil and plug at regular intervals, check and adjust valves if necessary after every 200 hrs of use and have always run synthetic oil, I'm a little surprised it has lasted as long as it has.

 

[redmondjp]

There won't be any problem with an unloaded speed of 3700rpm.

 

[Rivets]

Personally I would not exceed 3600 RPM's on an engine that old. Just my opinion.

 

[redmondjp]

Personally I would not exceed 3600 RPM's on an engine that old. Just my opinion.

Yes, but an additional 100rpm is only a 2.8% speed increase - hardly noticeable.

 

[bertsmobile1]

There won't be any problem with an unloaded speed of 3700rpm.

It is a bit quick but considering the engine will not be running 24/7 you should get away with it