For those of us in the colder part of the world, we all know, winter is coming... That means that it is time to get the snowblower tuned up.Back story:
A few years ago, when I moved into the new house, I looked at the drive and figured I could just shovel it myself... "oh, it will be a good workout!" Yeah right.
The driveway is about 350 to 400 ft. We had a brutal winter that year. A lot
of snow... after the first snow fall and subsequent shoveling, I immediately went on Craigslist and found a snowblower. It is an Ariens ST420. A 2 stage 4 HP blower from the late seventies. Ad said, it ran last year but would not start so instead of fixing it, the owner bought a new one. $70. So I went and looked at it. Gave a tug on the starter and while it turned over, it would not start. So I offered the guy $25 for it and loaded it into my truck.
Got it home, cleaned it the best I could (it snowed the next day) and fire some starting fluid into the carb . It fired right up. Used it that winter by sarting it every time with starter fluid. The next winter I went to order a carb rebuild kit for it an found a new carb was only a few dollars more. Ordered it and put it on and had an easier time using it. This past winter, the motor seemed to have less power. Thankfully, we didn't get anywhere near as much snow, but it kept stretching belts because it did not have the power to move the snow etc...
This year, I have decided to give it a new heart. I am replacing the original 4 HP engine with a 6.5 HP Honda clone. The replacement engine has good reviews and even has a go kart racing culture popping up around it. Apparently, with some hop up parts, I can get 27 HP out of it
So here is the start. The blower in it's current state (I had already started dismantling it):
This is the 6.5HP Predator engine I am putting in:
No adjusting or adapter plates required. It fits perfectly into place. Almost like it was meant to be there.
Comparing the engines output shafts, they are the same diameter and located about the same height from the bottom of the engine:
The crank pulley even fits nice!
But now we see the first problem. Anyone see it?
Yup, the eagle eyed will see that the old engine has 2 output shafts, not just one. The old engine has a pulley that comes off the cam that rotates in the opposite direction from the crank output shaft.
While I can get a pulley from a new model that is essentially a double pulley, it does require an adapter sleeve (3/4 to 1"). Not really a problem to buy (going to order it tomorrow) The real issue is that pulley that spins in the opposite direction? It drives the wheels. So if I don't do anything, I will have 1 forward speed and 4 reverse speeds!
So now I have to figure out how the drive train works. The belt drives a spinning disc, when you pull the drive lever, it pops up and makes connection to a dirve wheel which in turn drives the wheels. When you select a speed, there is a U shaped fork that slides the wheel to a different position above the disc. The closer it is to the center, the faster it spins, driving the wheels at a higher speed. At its slowest speed, it is towards the outside of the disc thus spinning slower. Move it into reverse and it goes past the center of the disc and spins in the opposite direction.
I pulled the contact wheel and shaft to have a closer look.
I forgot to take a picture of it in the blower chassis. You will have to imagine a spinning disc (much like a record, remember those?) perpendicular to the big wheel.
Took it apart to get a better understanding:
At first, I thought I could just reverse everything. Nope. Can't do that. The big drive gear (not pictured) will not fit on the other side. Too much in the way. I have to either come up with a way to spin the drive platter (for lack of a better term) in the opposite direction or add an intermediate gear to spin the wheels in the opposite direction.
Hmmm. Another idea might be to move that drive wheel down the shaft so it would work in reverse?
There are some things in the way, I might not get full movement. Maybe go from 4 forward speeds to only 2... I only use 2 speeds anyway. The lower ones... if i push the drive wheel past the center of the platter, I would only get the higher speeds. I think I have that right.
I will try to get pictures of the guts to explain what I mean tomorrow.
Until then I will be
trying to figure this out.