How important is the alignment of the camshaft over the lower drive & auger pulleys? - Snowblower Forum : Snow Blower Forums
 
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post #1 of 7 Old 12-28-2014, 08:40 PM Thread Starter
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How important is the alignment of the camshaft over the lower drive & auger pulleys?

I am putting a new engine on a two-stage snowblower and I have a question about aligning the camshaft with the lower belt pulleys. The thread about the swap is here, but this seems like it's own distinct question so I am creating a thread for it. I hope this is ok.

As I see it there are three alignment issues when placing the engine. 1) Fore/aft, 2) side-to-side, and 3) parallelness. (And height, which is not an issue for me on my project but I imagine height impacts the three alignments in different ways for each.)

For each of these, can you comment on how important precision is and what might go wrong?

1) Fore/aft - I know that this can be adjusted using spacers so it's not a critical question during installation unless the engine ends up too far forward. But how much does it matter if I am little bit off... like if I screw up the adjustment or encounter some other obstacle?

2) Side-to-Side. The center of the lower auger pulley is not aligned side to side with the lower drive pulley. Assuming the camshaft is dead center of the lower drive pulley and off-center compared to the lower auger pulley I assume the following: placing the camshaft off-center of the drive pulley and closer to the auger pulley will make the drive belt tighter and the auger belt looser. Placing the engine in the other direction, away from the both lower pulleys will tighten both belts. How precision is the tension on these belts and will a 1/4 inch in either direction make a difference?

3) Parallelness. This is if the engine is crooked which results in the top pulleys being crooked compared to the lower pulleys. As an initial question, how tight are the tolerances when manufacturing snowblowers? A bit of play in the four mounting bolts is enough to end up with some crookedness. Now assuming I do the best I can in my garage given the 10 degree weather and oil slick on the floor how much error is going to be catastrophic and what will that catastrophe look like?

What I am hoping you will all say is that none of this matters, just eyeball it and go!
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post #2 of 7 Old 12-28-2014, 09:17 PM
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I just eyeballed mine and it was close. Just mount your pulleys to the new engine and stick the engine on top and eye ball things as close as possible. On most blowers the friction disc for the drive actually moves forward and backward when you engage it so that one has some movement built in. You just want to make sure things are straight enough that the belts don't wear prematurely. I would worry mostly about the auger belt since it has the most load on it.

Some lawn mowers and other machines actually have the belts twisted from the factory to turn 90 degrees.

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post #3 of 7 Old 12-29-2014, 10:24 AM
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The closer the crankshaft is to parallel to the impeller and drive shafts in the machine will increase your belt life. Same thing withthe pulley to align with the pulleys on the impeller and drive.
You can raise or lower the motor on the tractor unit as long as you run appropriate length/width belts assuming the idler pulleys will still tension the belts.

Usually they will be pretty close for your needs just by eyeballing the alignments.
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post #4 of 7 Old 12-29-2014, 10:37 AM
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On the MTD I just bolted it down to the existing holes and on the Montgomery ward Gilson I seen that under the 3/16th inch top plate was predrilled holes for the 5hp Briggs which matched the Predator perfectly so I drilled them out and bolted it down. Real easy not too hard at all. Plus the 8hp Tecumseh does that have the same bolt pattern as the 212cc Predator? As to alignment just Eye ball it. If you are off to much it will inrease belt wear as said above.
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post #5 of 7 Old 12-29-2014, 01:08 PM
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I know it's a little late but sometimes if you can get your hands on a half inch plate ,you could bolt/weld to the existing holes on the frame ,then drill and tap holes to fit the engine.
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post #6 of 7 Old 12-29-2014, 08:20 PM Thread Starter
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Quote:
Originally Posted by GustoGuy View Post
...the 8hp Tecumseh does that have the same bolt pattern as the 212cc Predator...
Same bolt pattern but the engine sits on top of the bolt pattern differently. I can bolt the predator into the same holes the tecumseh was bolted into but the camshaft ends up too far back and to the left. So the new holes are drilled forward and to the right.
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post #7 of 7 Old 12-29-2014, 08:22 PM Thread Starter
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Originally Posted by Bob Cat View Post
I know it's a little late but sometimes if you can get your hands on a half inch plate ,you could bolt/weld to the existing holes on the frame ,then drill and tap holes to fit the engine.
That's a good idea and if I screw this up that is what I will do!
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