Tuning and RPMs Under Load - Snowblower Forum : Snow Blower Forums
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post #1 of 11 Old 01-13-2016, 06:27 PM Thread Starter
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Tuning and RPMs Under Load

I've got a question about tuning the engine on my Ariens. It's an early 70s 5hp Tecumseh. I recently picked up an RPM/hour meter and it works pretty well. I've tuned the engine to just under 3600 RPM at full speed with no load.

My question is: when the auger hits some snow the RPM drops to about 3200-3300. Is that to be expected or should I be able to adjust how much the throttle opens to maintain 3600?

Thanks.
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post #2 of 11 Old 01-13-2016, 06:46 PM
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A tach is some great insurance for minimal investment.

That's a typical RPM drop if you're really stuffing its face.

the only way to really get more out of it would be to boost compression or mess with the impeller pulley ratio (increase torque at the expense of velocity/throwing-distance).


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post #3 of 11 Old 01-13-2016, 07:05 PM
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i would guess that your rpm drop puts that engine right in its peak torque happy place !

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post #4 of 11 Old 01-13-2016, 07:53 PM Thread Starter
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Thanks for the feedback, guys. I guess I was just hoping to get a little more throwing distance. It works fine but it's not as far as I'd like and on my drive I can end up throwing the snow in the middle twice if it doesn't clear to the side.

Plus this.
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post #5 of 11 Old 01-13-2016, 08:03 PM
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Impeller mod would help if u haven't already
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post #6 of 11 Old 01-13-2016, 09:58 PM
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Quote:
Originally Posted by Michael303 View Post
I've got a question about tuning the engine on my Ariens. It's an early 70s 5hp Tecumseh. I recently picked up an RPM/hour meter and it works pretty well. I've tuned the engine to just under 3600 RPM at full speed with no load.

My question is: when the auger hits some snow the RPM drops to about 3200-3300. Is that to be expected or should I be able to adjust how much the throttle opens to maintain 3600?

Thanks.
Are you hitting a lot of snow, or just an couple of inches. If its just a bit, maybe the governor needs a bit of adjustment.

If its a good size pile, especially if its wet or heavy, it's normal for an engine to slow down some when its chewing big piles. The governor does the throttle adjusting to keep the RPMs up, but it cannot make the engine provide more power than its designed for. That said, make sure you have the throttle wide open when you are working, because if its set to slower speed, the governor will not be able to maintain power.

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post #7 of 11 Old 01-13-2016, 10:26 PM
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Carburetor tuning/performance could be off. Is it adjustable?

It does not sound out of the ordinary but I have had sound running machines that appreciated an tweak of the high speed needle and responded stronger.

Pete
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post #8 of 11 Old 01-14-2016, 11:33 PM Thread Starter
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The last snow was 3 or so inches. It was a little wet but nothing it should bog down on. I'll take another look at the governing this weekend. I'm not familiar with the adjustments but maybe I can get the throttle open a little more when the governor kicks in.

Thanks again for the feedback, guys.
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post #9 of 11 Old 01-15-2016, 06:59 AM
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engine may be a little lean. If you have an adjustable carb try to richen it up a little.
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post #10 of 11 Old 01-15-2016, 09:38 AM
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Quote:
Originally Posted by Michael303 View Post
I've got a question about tuning the engine on my Ariens. It's an early 70s 5hp Tecumseh. I recently picked up an RPM/hour meter and it works pretty well. I've tuned the engine to just under 3600 RPM at full speed with no load.

My question is: when the auger hits some snow the RPM drops to about 3200-3300. Is that to be expected or should I be able to adjust how much the throttle opens to maintain 3600?

Thanks.
Sounds like the governor....when settings are at extremes of major and minor it will either dog or over-rev......there is a sticky thread, as well as other posts that have great info
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