Small engine tech / redneck projects

[dremu]

I donno, maybe this is a Lounge thing, but ...

buddy gave me a coupla lawnmowers, edgers kinda thing, little 2.5HP B&S motors. Hey, "free" is the GOOD four-letter F word

So I'm thinking of building a little gas-powered generator or air compressor, roll it into the pick-n-pull and run my impact tools

First up, I hate yankin the damn string though. Can I get electric start for such a little engine? I presume it's some sort of uni-directional clutch and a little motor?

Then, I'm kinda torn. To do a generator, I'd just hook an alternator to the motor with a V-belt, presuming I wire the thing for one-wire, a small battery, and off I go. 12V anywhere as long as I have gas

To do an air compressor, I could put a spare A/C compressor on there, or maybe get an electric air compressor and use the gas motor instead of the electric.

However, the one part that stumps me here is the pressure switch. On an electric air compressor, right, you turn the motor off and on when the tank fills up or gets too low, respectively. With an A/C compressor, you'd engage the clutch or disengage it. However, both of these require electricity ... so now I'm to running an alternator AND some variety of compressor off this poor little lawnmower engine.

S'pose I could just use a little motorcycle battery, but then I gotta charge the thing somehow, and it'd be nice to have the unit self-contained.

Any other ideas? Could rewire the alternator for 120V ... I do actually have a 1kW inverter around here somewhere, could use it, though I'd hate to run power tools off it. Other than a gas blender (I don't drink, and 2.5HP is a bit much!), any other uses for small motors?

-- A

 

[diesel4me]

kinda small....

A 2.5 hp motor isn't really big enough to run either a compressor or an altenator--I've tried using a 3.5 hp,and that was laboring pretty hard trying to spin a GM altenator...a 5 hp would be a better choice..I've used a few 2,5 hp tecumseh and briggs motors on go-carts and mini bikes with fairly good results,but they wont spin the tires or climb much of a hill--ok for tarred level ground with a smaller kid on them..

You CAN get 110V out of a gm altenator,but its a bit complicated on an internally regulated one--you have to remove the regulator and ground one of the brushes..a easier way is to use the inverter,its a lot simpler..or you could use an old school pre-72 externally regulated altenator,and wire it up so you can switch the regulator in or out of the circuit,to switch from 12V to 110V--to get 110V it must be run at a constant speed,any rpm fluxuations will increase or decrease the voltage..the inverter works better..

You can convert a induction motor from a washing machine or other similar appliance into a generator by adding a few capacitors to it,and spin it with a gas motor--110V will come out of the cord! --but they wont run tools with hi amp motors like a circular saw--best for lights and small stuff like drills or a jigsaw...again,2.5 hp might not be enough..a search on google for "Homebuilt Generators" will bring up some interesting pages!--one website is www.theepicenter.com

I did make a 12V power supply by putting an old 12V generator from an early 60's GM on a 2.5 hp briggs motor--and I could use the generator as a starter to start it as well!..they had starter-generators on many old lawntractors..but they were a better starter than a gererator(feild coils were wound with heavier wire for use as a starter,it only puts out 10 amps or so for charging the battery)..mine would barely start a 2.5 hp motor without cooking it!...

Its possible to use a car starter on a small engine,the best is the older ford ones with the huge bendix drive facing backwards used until 1964 or so--you coud remove the bendix,and it exposes a long shaft ,and it has no "nose" to get in the way,looks like a normal electric motor--its a simple deal to put on a pulley and an idler pulley on the motor to tighten the belt to start the engine..cant leave it engaged after it starts!--I tried wiring one of those like a starter generator--it started perfectly,but it only put out less than 10 amps,and the bushings didn't last long in the starter...

You need a pretty good sized motor to spin an air compressor..5 hp at least..you might get away with the 2.5 hp motor running a GM altenator with the inverter,and use the 110V or 12V to run one of those small compressors that plug into the ciggarrete lighter or a house outlet..

As for the pressure switch,a gas engine powered compressor uses a "constant unloader valve" that free wheels the pump when the full pressure is reached--it applies air pressure to the intake valve on the air pump and hold it open,so no compression occurs,until pressure drops low enough for it to "kick in" and let the valve close so it will pump up again..its a bit complicated to hook up--I tried putting a 25 hp ONAN engine on a huge air compressor I bought,hoping to make it into a portable sandblaster rig--but even 25 hp didnt seem like enough HP to run it,even though it only has a 7.5 hp electric 3 phase motor on it--and the unloader valve would have cost 150 bucks..so I put the electric motor back on it--and its up for sale!



have fun!!

 

[REDCRO_REDNECK]

if the motors are realy old restore them and keep for decorations the old N series briggs motors look really neat if that is what you have.

my dad bought 2 of them, I got both running with out much effort.

 

[diesel4me]

I had some!..

I found 2 antique Briggs motors in the rubbish left by the curb many years ago,one was a 6N series,the other was a 5"S"..like the ones used on old reel type mowers--I got both running in about an hour,only had to clean the points and carbs out!..but I put them in the shed for several years and neglected to drain the gas out,and they got all varnished up --stupid of me,I know better!..

I found an small engine website online that had a free classified section,and I needed money,so I advertised them for sale..I got 75 bucks for the pair and they guy was happy to get them! --he lived only a few towns away so he picked them up..I also sold him a model "A"briggs motor and a model "ZZ" briggs for 75 each--probably worth more,they were really old,but I had no use for them other than to display at small engine shows I hadn't been to for many years,so I sold them..they got a good home!.. I still have a model "19" out in the shed collecting dust--it smokes pretty bad..

 

[cbbr]

Make something really useful - a gas powered blender.

 

[diesel4me]

winch motor??

I had one hooked to a riding mower tranny that just had forward and reverse--used it to drive a winch on a small utility trailer...worked good,but starting it up was a PITA sometimes in crappy weather...