Hi, I picked up a 3.5 B&S lawn mower engine for kicks (and for free), and I want to use it in some way (not sure yet) but everything I've thought of
would virtually require horizontal output. I have been disassembling the engine to check potential problems, and I've come up with the following:
Carb: I can turn it 90 deg. relatively easily, with the help of a flexible hose
gastank: mounted to the bottom of the carb. both must always be upright
(oh and I might have to figure out how to run a larger gastank!)

these pose the biggest potential issues:
L-head design: It is possible the design of this 2-stroke L-head won't let it work vertically. I'm not sure why but I have considered it. There IS a strange module at the base of the 2 valves (by their springs) that has a large hole in it and some kind of diagphram inside. it's about the size and shape of a pack of gum. Not sure what it does but maybe, since this hole is lower than most of the module it is intended for oil to flow inside or something. edit: the parts list calls it a breather assembly
Oil sump: the sump and oilpan exist right above the rotor. However I find myself wondering, could I not abandon the sump and just run 50:1 gas/oil fuel? or would that not work. I could possibly try to redesign the sump but I haven't figured out how to open the crank yet

can't think of any other problems off the top of my head. your input is appreciated!

hovercraft.Saw one on the show little peole or whatever its called on dish.All ya need is one the same size with a horizontal shaft for the prop for forward movement.Not much else its good for except a lawnmower or a really powerful and loud ceiling fan.

the engines off of lawnmowers kinda rely on the blade to act as a flywheel, without the extra rotating mass they're kinda gutless and die easy... I've thought of just making a round steel plate for a flywheel and balancing it, but haven't gotten that far...

the oil system is just a slinger powered off of the crankshaft or camshaft, I don't think you'll be able to make it a horizontal engine for that reason alone. as far as getting the crankcase to split, all that's holding it together is the bolts around the bottom, and the rust around the output shaft at the lower crank bearing. if you really want to take it apart, have the engine upside down, take emery cloth and clean off the crankshaft at the crank bearing seal, get all the bolts out holding the bottom cover on, carefully pull the cover off, try not to shake much around as I did when I pulled apart the 3.5 briggs I took apart in high school, the cam and crank gears weren't marked, so I don't think I had them in right...

the other way to do it is just leave it horizontal and run a belt drive, a V belt can be turned 90 degrees without a problem...

well, ya see as I have no other engines and no money to spend on this little project, unless I can find a horiz. motor for free all I got to work with is vertical shaft motors. So if it can be done, I will do it It's one of those projects entirely based on free junk and lots of labor.

ok, another thought, I don't think there's enough crankcase room, but the horizontal shaft engines just have splash oiling via a finger on the end of the connecting rod, maybe you could swap the connecting rod and extend the future bottom of the crankcase somehow...

Awhile back i saw a abanded riding mower in somones yard and i went to look at it to see what motor was in it.It was a briggs.And actually there was a pulley or 2 up front from the engine running back to the rear end and the blades.Go to a mower repair shop or go online and look at some of the parts schematics and youll see that theres some that have the belts twisted all sorts of ways to make them work at different angles.

I have thought of the belt-twisting, but that's my last resort. I would like to get it to work horizontally if I can
As for a flywheel, yes it's gotta be kinda gutless at 3.5HP but it actually does have a steel flywheel on *top* that serves all sorts of really nifty purposes- providing spark, raising idle speed when it starts, and of course starting..

update: i thought it was a 2 stroke, but upon reconsideration I don't think that's the case- the exhaust valve and intake valve are never open together. I think it's a 4 stroke.

Yep, it is a 4 stroke. It can be converted to run horizontal with the correct parts and some aluminum welding (for the oil filler/sump) but the question in the end is it really worth it? I started out working in my uncle's lawn mower shop when I was 9. I am now 52 and those years still rate up high on my list of best. Personally I wouldn't spend the time and effort to convert it but then I am not you so I'll stop right here and wish you good luck in your endeavor.

I guess at this point it will largely depend on what I can get my hands on cheapest. I'd prefer horiz. and there's a welding rig at my school, but if I can get a pair of bevel gears that might be a better choice. Only problem is vert. mounting would limit the applications, cause it would require more space and weight.

p.s. I've read L-head's biggest problem is breathing, so they get like 7:1 compression. Would it be feasible to put a small homemade supercharger on this thing? (by small I mean the intake pipe is about the diameter of a nickel) Not looking to boost the crap out of it, just to raise the compression ratio to a more normal 9 or 10 to 1.

The flapper valve you were refering to is a crankcase breather somewhat like a PCV valve in a car. If they stick, it makes the greatest oil fogging machine you've ever seen. Spent 35 yrs running a small motor shop working on those suckers plus many others. Wouldn't make a good plane motor as it's much to heavy for the power it puts out. Friend of mine and I had a Quadra 200 that weighed about the same but put out 24 hp.

[X(]Hi, I don't think anyone has caught this but you said the intake and exhaust valves were not open togeather so it must be a 4 stroke. The thing is after 30 plus years as a mechanic i have never seen a 2 stroke with valves. if it has valves it is a 4 stroke, 2 Strokes have Ports or reeds.
Have a great day. [sm=72_72.gif]
Waterloged

yup, I'm pretty sure it's an L-head 4 stroke now