Whirlwind stump puller

[Viking Life]

I have a 72" stump puller on a stock 220. What pitch should I be running on the prop?

[akblackdawg]

what ever pitch it takes to pull the rpm's you want the motor to turn, will be different depending on the power of the motor, start at a setting of 2, and go higher or lower to get the max out of motor.

just noticed this is your first post, welcome to SA, feel free to ask. i'm a car motor guy or could tell you more about your 220, but pitch setting is pretty basic, you can also play around with the search function and find answers to almost any problem in the world on here. If you are new to airboating, don't hesitate to ask, we all want you to slide safe.

[Viking Life]

It says that was my 1st post? Weird. I've been on here for a while. Thanks for the input tho! Been in the glades since I was a kid but stepped away for a bit. There were no carbon fiber props back then. So I built a new boat and got this stump puller prop and wanna make sure the pitch is right on this stock 220

[akblackdawg]

a stump puller isn't normally used with ac boats, i had a panther with 383, 2:1 box, and used a 3 blade stump puller. i'm sure some will suggest a different prop. stump puller might be too wide to work well on ac boat. look at WW website also for more info.

[Comanche-pup]

Got several friends with stump pullers on their AC motors??? Couple on GPUs??? Not sure what you talking about blackdawg?


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[Bruce]

set it where it turns 2800 line up the casting mark on the blade with the 25 on the hub and see what u got

[WhirlWind Propellers]

Just a quick note on the older Stump Puller blade series. This blade style is known as a workhorse, so there are still many of these blades around, and we can still make new ones on request.

The Stump Puller series came in both a standard 72" (max RPM 3000) and a 78" (max propeller RPM 2700).

*The direct replacement for the Stump Puller 72" is the Whisper Tip 72" and the direct replacement for the Stump Puller 78" is the Whisper Tip 2.0 78".

The Stump Puller 72" is a wide-blade, and as a 2-blade is often best matched to an a/c 520 or 540, or a big-block direct-drive auto engine. Though I have seen them on smaller 4-cyl a/c and 220 GPUs, just with a lower blade angle. For a direct drive set-up, the most important factor is setting the blade angle to get as close to 3000 RPM WOT (or a little lower on a/c motors) without going over.

So to answer your question, as others have said, the pitch you need to set the Stump Puller 72" is the one that holds your motor at your target WOT RPM, without letting it go over 3000 RPM. For a static set-up, you want to undershoot by about 200 RPM for your WOT on the water RPM target. If you line up the seem line of the blade with the numbers on the hub, this will give you a starting point. Do a run-up and see what RPM you get, then stop and adjust the angle up or down. Each degree of pitch change makes about 100 to 200 RPM of change on the engine. It's a pretty fine resolution. You can usually dial it in perfect in 2 to 3 runs.

Sincerely,
Patti