McCulloch Alternator

What this is: In November 2004, a 1200 watt Mcculloch alternator (57k) became available on EBAY. The advertisement said that it did not run, and that the motor did not have compression. I won it for $28.89 plus shipping (with the cost of shipping and parts, I've got way too much into this thing, but it's been a fun project) When I received it, I knew I had a big project. The gas tank had old gelled gasoline and a lot of rust inside, and the "fuel well" was completely missing. The carburetor was completely gummed up with solids in the passageways where liquid gasoline was supposed to flow. Also, it seemed like the motor had very low compression. It was no small wonder this thing did not run! On the plus side the motor did turn over, and everything seemed to be there.

Initial Starting Attempt: After cleaning the gas tank, figuring out how to replace the fuel well that is part of the tank (15k), and overhauling the carburetor, I re-installed the parts on the engine and tried to start it. It would turn over, but refused to start. I thought that maybe it had no compression, so I pulled the head to be sure that the valves and cylinder walls looked good. They were OK. Even though I had spark and a new spark plug, I installed Briggs and Stratton's Magnetron electronic ignition (PN 394970) (3k). The engine really didn't need this, but I figured as long as I was in the motor, installing an ignition system that has no moving parts would eliminate a lot of uncertainty about the quality of the spark. This part cost about $15 at Northern Tool and Equipment.

Back to the Bench: Over the next day or so, I decided to try to remove the alternator from the engine. I was unsuccessful in removing the permanent magnets (24k) from the engine (on this try - I was successful a day or two later), but I was able to easily remove the generating coils (28k) where the electricity was made. Once the coils were removed, I tried starting the engine. What a difference! The engine turned over and inertia from the flywheel and magnets allowed the engine to continue to spin for a much longer period than before, and after a couple more pulls on the starter rope it finally came to life!! Apparently, the inertia from the alternator magnet assembly gives the perception that the engine has low compression.

I examined the two coils that I had removed earlier, figuring that they were somehow the reason the engine would not start. It appeared that they are supposed to be connected in parallel, with each coil contributing about 600 watts to the output of the machine. Both coils were damaged, one very badly. I installed the better of the two coils and ran the machine. It worked! I repaired and installed the second coil, connecting it the same way it had been connected before. Once again, the engine would just not start and run. Thinking about the problem, I realized that the second coil was connected out of phase with the first coil, causing what is essentially a short circuit to the generator, which is a very big load (Ever try to start your lawnmower while it is standing over uncut grass? This is much the same condition). When the coils were correctly connected the engine started and ran just fine. I've also figured out that I can easily wire this machine up to supply 220 volts at 1200 watts if needed, but I've not tested this. (note: One warm day last winter I had the bright idea to connect the coils in series to get twice the voltage, and then run the engine a slower speed to reduce the voltage {and cycles per second}. I thought that I could then use the engine to run a heater in my camper with less noise coming from the generator. The results of this test were less than optimal. At the lower engine speed the engine could produce enough power to run the heater effectively.)

Testing the alternator, I find that it will supply power not only to a 1500 watt heater without any difficulty (125 percent rated load), it will also supply the heater plus 350 watts of Christmas lights as well (1850 watts total - over 150 percent rated load). I've also tested it with my furnace fan, and it will run the furnace quite nicely as well. A 1500 watt heater and 700 watts of Christmas lights overloads the alternator to the point where there is little output from the heater. Voltage regulation with this machine is about like my home-made alternator. No load, I see about 130 volts. With a 1500 watt (125 volt) heater running, I see about 100 volts. Also, with the 1500 watt load the throttle is wide open.

Lubrication: Testing also revealed that the 3 HP Briggs and Stratton engine leaked a lot of oil from the crankcase. The problem was found to be a cracked block that started with one of the bolt holes that is used to hold the crankcase cover assembly on the motor (the end of the motor the power take off end of the crankshaft sticks through). The repair was to replace the bolt with a slightly longer bolt and back it with a nut, and then fill the area of the crack with JB Weld. The repair mostly worked (meaning it slowed the leak considerably). I need to take the time to find the remaining leak and this will probably involve more JB Weld. UPDATE: I ran the generator under load for a bit over an hour, and found that it used a lot of oil - about 6 - 9 ounces. The leak is still there, but it couldn't have leaked as much as it burned. If it leaked as much as I poured in to replenish, there would be a large puddle. There is only a small puddle, and it is small enough that the puddling stays on the mounting frame and doesn't drip on the ground when being run for an hour. The machine also creates a lot of smoke, so I can't run it inside my 8 by 10 metal storage shed unless I keep the doors open. I'm using 5W-30, and that may be part of the reason it's burning so much oil. See below ("New Engine") to read about how I finally solved the oil leak.

Efficiency: This little motor has a 2 quart gas tank, and seems to use a lot of fuel. It will run about 2 hours on a tank of gas. For now, this is just as well because it will also use enough oil (burning and leaking) to require that the oil be filled as well. For those of you that are mathematically inclined, 2 quarts of gasoline is in rough terms 55,000 BTU's. This alternator is rated at 1200 watts, so in two hours it can make 2.4 kwh, which is 8,200 BTU's. Doing the math, 8200/55000 = about 15 percent efficiency. If you can buy gasoline for $1.80 per gallon (the going price in January 2005), each kilowatt will cost you about 38 cents just for fuel. Where I live I can buy electricity from the power company for about 8 cents per KWH (including taxes and other fees) in the winter. As you can see, no one is going to get rich selling electricity to the power company with this machine!

Muffler: I fitted the engine on this alternator with a "plumber's delight" (57k) muffler in an effort to reduce noise. The exhaust port is threaded to take 1/2 inch pipe, so I installed a 90 degree street elbow in the exhaust port. Another length of pipe carries the exhaust up 6 - 8 inches to the muffler. A support rod is attached to the carrying handle and exhaust pipe to keep the exhaust from flopping around while the engine is running. The muffler is actually two Briggs and Stratton part number 5019 mufflers connected face-to-face (23k) with a short length of 3 inch diameter aluminum ducting, with a 90 degree street elbow on the outlet of the muffler. This contraption quiets the engine's exhaust to a nice quiet put-put-put sound very nicely. The (loud) noise that remains is the mechanical noise from the engine. This remaining noise, while much quieter than before, it still quite loud. Apparently these small engines were never designed with low sound levels in mind.

Muffler Update: The best muffler I have found (so far) is two cheap home depot mufflers mounted face-to-face with a piece of sheet metal (aluminum ducting works well) held in place with hose clamps. The only big problem I've found with this configuration is the muffler inlet isn't designed to handle the massive shaking it gets mounted on the end of a fairly long pipe. I'd still like to know how well a home made muffler would perform  (click here for a rough draft of my home made muffler - 83k), but I've not found the time to build one.

New Engine: (69k) Spring is here, so I decided it was time to fix the oil leak in my generator. Properly repairing the engine involved the replacement of the cracked block. Searching EBay for a couple of weeks a replacement engine was located and I won the bidding. This is what I found.

Once the engine was delivered and unpacked, I added oil and a bit of gas to test run the machine. It started and ran with very little trouble, so I proceeded with my grand scheme.

To use this engine with my generator, it needed to have a tapered shaft on the engine. Removing the gearcase that came with the replacement engine revealed that the shaft was not tapered. To remedy this, I swapped the crankshaft from the old engine. I found that the engine that was delivered with my generator had been severely abused (but ran well - see above), and was probably run without oil a time or two. The crankshaft and rod bearing surfaces showed evidence of scoring, but since I needed to have the tapered shaft I used it anyway. The other problem was the new motor had a ball bearing on the output shaft and the original motor had a plain bearing, and I was unable to remove the ball bearing to use on the old crankshaft. This made the new crankcase cover unusable, To solve this problem I used the cover from the original engine on the new motor. The crankshaft support bearing in this cover was severely worn, but having little choice I used it anyway. I was not too worried about it because the seal shows no evidence of leakage.

Once the motor and generator was re-assembled, using everything I could from the replacement (carburetor, fuel tank, etc), I test ran it with several loads including the air conditioner on my camper. The machine seemed to work fine with no glitches.

Since the generator was working fine, it was time for paint. Flat black and scratched and faded yellow are not the most exciting colors. Since the generator housing was already yellow, I decided to paint this machine in my favorite color scheme - John Deere green and yellow. The resulting paint job isn't perfect, and I suspect that a lack of proper preparation will result in some of the paint not being very long lasting. But for now it looks great! (69k)

The serial number reveals this engine is even older than the original; if the shroud (and the numbers stamped in it) is original, the engine was built in 1962! Even though this engine is very old, it still starts and runs without any difficulty.

Other Notes: Does it will start when the temperature is below zero? Why yes, it starts quite easily when tested at -12 degrees Fahrenheit. I checked the oil, poured a bit of fuel into the empty tank, and primed it by pouring a tiny bit of fuel down the carburetor throat. Pulling the starter rope a few times the motor came to life just as easily and ran just as well as in warmer temperatures.

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