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Upgrade Mighty Mac chipper from 7 HP to 10 HP


CanadianGuy's Avatar
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12-19-11, 07:26 PM   #1  
Upgrade Mighty Mac chipper from 7 HP to 10 HP

I recently bought a 1986 Mighty Mac chipper with a 7 HP B&S motor. The motor works fine now but I'll be chipping a lot in the spring and suspect it'll burn out as those old motors require lots of attention to the oil level. New Mighty Macs look just like mine but come with 10 HP motors. Does anyone know if I could easily upgrade mine and, if so, what parts would need replacing? Thanks

 
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12-20-11, 05:54 AM   #2  
Ha, ha, ha. I had (I guess I still have it...) one of those. Mine was the type where the engine assembly could be attached to the chipper/shredder or to a roto-tiller or several other attachments. My wife lovingly referred to it as the Franken chipper, Franken tiller and then finally the Franken pump. As it broke I would repair it with misc. parts until it was no longer recognizable. I think the only thing that remains of it is the motor mounting plate, battery mount and one guard and it's now a 2" water pump if you could even say it's the same machine.
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Which model do you have or what does it look like? The older models were rather long and often had four wheels. Newer models are more upright with two wheels and a tow bar or handle.

Don't bother upgrading the engine. The stock engine produces all the power that the chipper/shredder section can handle. More power will just cause other things to break. Just keep an eye on the oil level and run it until it dies and then recycle the metal. Any money you were planning on investing in a new, larger engine just save to buy a replacement chipper if/when this one ever dies. Depending on how much you use it, it could last quite a long time.

If you have the model I'm thinking of, keep in mind that it is a light duty shredder and a very light duty chipper. Wear ear plugs because it's loud, especially with chipping. Wear safety glasses because it is not up to current safety standards and throws a fair bit of chips out and the occasional piece of steel. And, NEVER, NEVER, NEVER get any part of your body past the edge of the infeed chutes. If something is stuck or you want to push material in use a wooden stick. Also resist the urge to push sticks into the chipper section. It may be OK once in a while but the chipper shakes the stick quite a bit making your hands numb. OK for short periods but can lead to permanent damage if done long term.

 
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12-20-11, 06:30 AM   #3  
Thanks. The model I have is a 12P and looks almost exactly like the brand new one at MacKissic Inc.. Aside from the bigger engine, the only apparent differences are that they now use pneumatic tires and positioned the chute on a bit of an angle. This one replaces a battered 5 HP 1985 Mighty Mac 12P that I was given years ago. I burned out that one's old B&S pretty quickly because I did not know about having to constantly check the oil. Replaced it with a Honda motor I got on sale for $200. It's been very useful because I tow it into the woods with my garden tractor and chip deadfall on site, spreading the chips over my trails. The Honda motor has been fantastic but the chipper's side chute fell off from metal fatigue and I can't use the top chute because the screens were missing. The "new" one is not only more powerful, but has all components and appears to have seen little use over the years. The motor is a 7 HP B&S 170402-2336 which seems to have been very popular based on the amount of replacement parts available online. I think this one was originally built for a snowblower. Though the chipper hasn't been used in years, the motor starts on just one pull. But I'm worried about forgetting to keep checking the oil next spring as I chip the cuttings from a project this fall in which I trimmed trees and cleared all the growth below the power line that runs 350 feet from the road to my house. I thought about renting a big chipper but there's no way to get it to the site so I'd have to lug all the cuttings down to the driveway and then lug the chips away.

 
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12-20-11, 08:31 AM   #4  
My dad got me into the habit of checking the oil every single time I start a small engine. Only takes 15 seconds and can prevent having a really bad afternnon.

 
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12-20-11, 08:44 AM   #5  
If the engine is in half way decent shape it should be no problem keeping it oiled. Just get in the habit of checking the oil level before working or every time you add fuel and you should be fine. I don't think it's worth spending the money to upgrade engines now. If you do forget and run it out of oil you can always get the engine then.

I am with you about the Honda engine though. I love their x series engines. I have several of them. They are relatively quiet and mine get abused when they are working, forgotten when their not working and they always start right up and run like a champ. To this day I still have not had one that needed to have oil added between oil changes, and they have a low oil shutdown in case you ever do forget.

 
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12-20-11, 09:09 AM   #6  
I had a 12PT they are one awesome chipper, mass destruction in a box, don't forget to sharpen the knife blade on the side. Have a good one. Geo

 
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09-14-14, 12:14 PM   #7  
Speed up belt tensioning

When we first started using our Mighty Mac 12P, I was concerned about how much time it was taking to re-tension the belt. The instructions call for re-tensioning hourly for the first 5 hours of operation.

Most of the time was taken loosening and then re-tightening the four bolts that clamp the engine to the chipper's chassis. I had to get a wrench on both the bolt head (above the chassis) and the nut (below). I would guess it was 10 minutes to loosen and 10 to tighten.

I replaced the hex nuts with wingnuts (5/16-18 in our case) and that has cut the re-tensioning time to about 5 minutes.

The wingnuts have nylon inserts, just like the hex nuts they replaced. If you can't find these locally, you can find them on Amazon (sold by *****).


Last edited by Shadeladie; 09-14-14 at 03:08 PM. Reason: Removed name
 
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