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The old H70 Tecumseh in my MF7 Hydro is nearing the end of its life, and I expect to hear the sickening POP sound of a rod going through the block before too much more. It's already been through one, so I'd recognize that sound again. With the absence of short blocks and parts in general, what are my options to repower? I'm not out to boost HP, since it's doing all I need now, but more wouldn't hurt. I'd like to avoid cutting the sheet metal if at all possible.

I'd like to find a drop-in replacement, but I know that's wishful thinking. Some of you out there must have had to go through this and I'd appreciate your input - including horror stories that might take me out of trying it. What are the pros and cons of the engines on the market? How difficult are the conversions?
 

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Red Tractor Fan
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I guess the two "best" bang for the buck swaps would be either the 6.5 or the 11 hp swap using the Harbor Freight Honda clone. The 6.5 may preform as good as your 7hp did because it's an overhead valve, but I have never been able to compare. The 6.5 will be a pull start motor with a complete drop in unit muffler & gas tank. You will need to fabricate a bracket to attach the cable to the carb. (being a pull start, I would just hand choke it.) This motor can be had for $99.00 all the time on sale.

The 11 hp would really handle anything with the MF7/8 tractor will be presented with. This motor is a full unit like the 6.5, but also has an electric start & a back up pull start. You will need to build a throttle bracket and choke if you like. The electric start will need the harness lengthened to be placed in the dash if you like. (reuse the key switch from the motor) These motors go on sale for $299 and with both of these deals, I believe you can use the 20% off coupon too.

I guess if you wanted to really push it, they sell a 13 hp motor too!

PS, check the reviews on Harbor Freight, even there these motors have an amazing feed back for being good motors. The go cart crowd just loves the 6.5 motors and there are a ton of them that go on rotor-tillers.

http://www.harborfreight.com/engine...al-shaft-overhead-valve-gas-engine-66014.html

http://www.harborfreight.com/engine...hp-ohv-horizontal-shaft-gas-engine-66492.html
 

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I have just fitted a Honda 5.5 in my MF8 it fitted without much trouble, it seems to go better than the Tecumseh.I had to drill new holes in the mounting plate to line it up,did away with the original petrol tank used the Honda. I intend to use it untill i have time to do the Tecumseh up. Dave
 

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The old H70 Tecumseh in my MF7 Hydro is nearing the end of its life, and I expect to hear the sickening POP sound of a rod going through the block before too much more. It's already been through one, so I'd recognize that sound again. With the absence of short blocks and parts in general, what are my options to repower? I'm not out to boost HP, since it's doing all I need now, but more wouldn't hurt. I'd like to avoid cutting the sheet metal if at all possible.

I'd like to find a drop-in replacement, but I know that's wishful thinking. Some of you out there must have had to go through this and I'd appreciate your input - including horror stories that might take me out of trying it. What are the pros and cons of the engines on the market? How difficult are the conversions?
You might want to consider using a Tecumseh HM series engine they have cast iron liner and you can get 8, 10, 11, 12hp units all about the same physical size. I think you would have a better chance of making it fit without cutting any sheet metal and have a longer lasting engine with more power so it doesn't work as hard.
 
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