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Couple of questions about a small engine

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Last sunday i visited a tool/flea market and bought this lawn mower engine. You can read the label, is a Italian copy of 3,5 hp tecumseh engine, i've changed the oil, checked it has strong spark, new spark plug fresh gasoline, and then i tryed and start it, it kicks back, also i heard couple of loud pops from the exhaust, the flywheel is aluminium and it doesn't have blade, i've heard on some engine blade acts like a flywheel is this the case here and can i turn this engine and use it i vertical configuration without taking it apart ?
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Comments

#2
the motor will not last as long in the vertical configuration as it would in the flat(horizontal) position.
but if you are set in doing it, you'll need to put the carburetor in the horizontal plane for it to work properly.

i suppose you could make a flywheel, or put weights on the aluminum flywheel that is already there.
but, you may need some kind of heavy duty safety guard to trap the flywheel (or weights) if it (they) should ever happen to separate from the crankshaft :eek::bonesrock:

another real problem is lubrication,
the flat engine uses splash lubrication differently than a vertical engine.
you will also need to consider a modification for either pressure lubrication, or modification of oil slingers on the crankshaft you have now.

if you really want to do it there is a way,
but you may be better off getting a vertical engine and save yourself a lot of trial and error, unless finding a vertical engine is not possible or probable.
 
#3
Sometimes if you hit something really hard with a vertical shaft lawnmower it will shear the flywheel key and that changes the ignition timing, it will pop or backfire, but it won't run.
 
#4
if you hit something really hard with a vertical shaft lawnmower it will shear the flywheel key and that changes the ignition timing, it will pop or backfire, but it won't run.
I've heard about this , but i don't know the history of this engine so i don't know should i install a blade and try starting it then, or remove the flywheel and check the flywheel key ?
 
#5
I've heard about this , but i don't know the history of this engine so i don't know should i install a blade and try starting it then, or remove the flywheel and check the flywheel key ?
Definitely check the flywheel key before proceeding. That kickback can damage other components. Assuming a traditional flywheel, adding a blade will have very little effect.
 
#6
Most of these engines came with an aluminum key in the flywheel. It's a safety feature of sorts. If the blade hits something hard the key will deform and stop the engine rather than let it destroy itself. When you remove the flywheel check the key. It doesn't take much of a deformation to throw the spark out of time enough to stop the engine. If the key is bad be sure to replace it with another aluminum one. A steel key could cause the flywheel to be destroyed or bend the crankshaft if you should happen to hit something.
 
#7
Solid advice, Projectnut but i don't think this engine will ever see another lawn mower again, maybe a small go cart or a generator.
 
#8
Generator would be a good use, you could run it vertically and wouldn't need to change the engine around. I've also thought about coupling a vertical engine to a rear differential.
Solid advice, Projectnut but i don't think this engine will ever see another lawn mower again, maybe a small go cart or a generator.
 
#9
I've checked the key on the flywheel, at first when i looked, it looked broken but when i removed it, it is a offset key, made from aluminium and totally ok. Now i'm thinking about attaching a belt pulley to act like a flywheel. Also the key can go one way in so is not upside down.
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#10
The blade definitely acts as a flywheel. I know this from personal experience. Taking a vertical engine and turning it sideways isn't a good idea. The oil pan is in the wrong place.
 
#11
On most vertical shaft motors used for lawnmowers the blade does act as a flywheel, the actual flywheel is very light. Those vertical engines used for other purposes like pressure washers will have a heavy flywheel like a horizontal shaft engine. The lubrication for vertical engines will not work when the engine is turned horizontal.

<slightly off topic>

Back in the dark ages my Dad ran a small engine shop. Some of the the old horizontal Clinton brand engines had a very heavy cast iron flywheel. We put one of those very heavy flywheels on a vertical shaft mower that also had a large heavy steel disk blade with replaceable tips. That was one of the smoothest running mowers but it would take forever to coast down to a stop when you shut it down, it took so long that we considered it dangerous!
 
#12
Years ago I had a Jacobsen 22" "Turbo Cut" mower with 4 sickle type blade ends attached to a large "suction lift disc". I think the blade/flywheel assembly weighed around 15 lbs. The blades were designed to turn to the center if you struck a hard object. I did hit something hard a couple times. When a blade turned to the center the flywheel was so out of balance you had no choice but to shut down the machine. Fortunately the blade end could be rotated back to the proper position and all was well. It was a beast to start with the heavy blade assembly and would take a couple minutes to wind down when it was shut off.

https://www.magazine-advertisements.com/uploads/2/1/8/4/21844100/jacobsen-rotary-mower-1.jpg

It was a tough old mower, but it was very tiring to mow 1/2 an acre.
 
#13
An issue that I ran into recently was a loose valve seat. Aluminum block engines have steel or cast iron valve seats and they have a tendency to work out when running an overheated engine. This would cause a backfire through the intake or exhaust depending in which seat came loose. This is a fairly common problem. A compression test will be low to none.
 
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