Outdoor Power Equipment (Lawn Mowers, Snow Blowers, Chain Saws and more) Discussions

I just started using my new hour meter/tachometer today on my blower, and it peaked out at only 3180rpm, but steadily displayed 3120rpm.  It is this one:

http://www.amazon.com/Tachometer-Kawasaki-Motorcycle-Generator-Snowmobile/dp/B0049IFX56/ref=sr_1_cc_1?s=electronics&ie=UTF8&qid=1321768364&sr=1-1-catcorr 
         

Using that horsepower-to-torque formula (HP = torque x rpm, divided by 5252), I get 8.66 HP at 3120rpm.  At 3600, it would be 9.993 HP.  For the formula I used a torque figure of 14.58, which I got by plugging in the assumed Tecumseh 10.0 HP figure at the assumed rpm of 3600, into the torque-to-horsepower formula (HP x 5252, divided by 3600).  Lots of assumptions, I know, but I had to get the torque figure that way so I could turn around the formula to get my horsepower figure at 3120rpm.

Anyway, I don't know if this meter is accurate.  When my son and I get his Ariens ST824 put back together again (took it apart to paint the inside of the housing; adjust the chains; replace the friction disc, cracked handlebars, and beat-up/bent impeller; serrate the augers using a Platinum 30 cardboard template I made while at Home Depot; greasing the chains, auger shaft, and friction disc shaft), then I will try my tachometer on his machine.  I may just pick up another meter to compare in the end. 

If the reading is the same on his, or close, then maybe it is the meter.  If he gets around 3600rpm at full throttle, then maybe I need to adjust my governor.   If I do have to adjust it, does anyone know how to do that?  It's only a three-year old Tecumseh L-Head 358cc.  Thanks for any help.

I will try your ideas first on Wed then I am planning to drill 1 inch hole so I have an easy access to the governor arm shaft.  Once I resolve this RPM issue, the blower will be very good.

blumonster wrote:

It is much easier from the backdoor (rear cover) approach.  I have a full access to the governor and the spring so it will be easier for me to adjust now. Thanks for the diagram.  I will let you know how this goes once I figure out how to increase the RPM.

I purchased one of those tach/hour meters for my Husqvarna snow blower.   It  cost $42.95 US.    The engine is a Briggs, 305, 1450 torque engine.     At full throttle it reads exactly 3600 rpm, 

I tried per aa335, but the governor shaft does not move at all.  It does blow snow ok so it really is not worth adjusting it since it does not sound all that good at higher RPM anyway.

if the governor shaft will not move then you have a problem with the governor.  in order for the governor to control the engine speed it must be able to open and close the throttle plate on the carburator.

MN_Runner wrote:
Since you were able to change engine speed by moving the governor arm, I suspect that the governor shaft is stuck to the governor arm.  You can try spraying a small amount of penetrating fluid at the joint and break it loose.

aa335: "Since you were able to change engine speed by moving the governor arm, I suspect that the governor shaft is stuck to the governor arm.  You can try spraying a small amount of penetrating fluid at the joint and break it loose."

  No.  He has moved the governor arm which should be bound (bolted) to shaft by the 6 x 20 bolt and nut.  The shaft should be turning when the arm is moved.  He says the shaft can't be turned so the arm is not bound to the shaft as it should be.  The bolt is probably loose or the shaft worn. 

  Carlb is right.  That shaft has to move.

NM_Runner:  "It does blow snow ok so it really is not worth adjusting it since it does not sound all that good at higher RPM anyway."

   If it's over rev'ing it won't sound good but worth adjusting.   The governor keeps the engine from over'reving.  It also keeps the rev's constant for any throttle setting.  At full throttle the engine will sag under load.  The governor will sense that and move to increase the carb throttle to get more gas and keep the rev's constant for the load.  Without a working governor an engine will sag when loaded and be pretty useless.

So how do we adjust it? How should MN_Runner proceed?

I sold my HS35 this afternoon.  The governor works and it does maintain the RPM (just not at 4000 like the service manual says) under the load and blows the snow reasonably well.  I just did not want to sink more money and time into this machine than I am willing to invest on a 30 year old machine as the parts are sometime obsolete and not available.  I would have kept the blower if it were upgradeable to GX160 but  the HS35 platform cannot take GX160 as G150 has a lower height.

Your HP formula has a fault, does the term "Torque curve" or "Power curve" ring any bells? You will have a maximum torque at a given speed, after you reach that speed the torque falls off. Were it not for the curve, you should be able to the the motor together until around 5000 RPM, that should put you in the 15 HP range.