replacement engine


Old 08-02-05, 07:34 AM
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replacement engine

this might sound ridiculous but would it be possible to put a 8 or 9 hp engine on a mower orginally equiped with a 5 hp? i need (want) more power.
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Old 08-02-05, 10:36 AM
Join Date: Jul 2003
Location: ill.
Posts: 68
length and and width of 5hpcrankshaft has to have similar match to new engine or your pulley wont fit. you will have to fine a crank that will match your pulley or find a new pulley that is similar to yours but fits the new crank. also bolt patterns may differ at base meaning you may have to drill new mounting holes. i have a 1972 5hp that runs ok but i know it will need overhauled or replaced eventually. i have been told 5 and 8 hp dont match but 8,9,10,11, and 12 hp do. you will probably have to find matching pulley that fits a wider crank. i wont know on mine until i take engine off. either way it is a project.
Old 08-02-05, 11:38 AM
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yes it would be a project, but thats ok. i would just get a new blade mandrel milled and find a pulley with the right id/od. even if the engine fit the old holes, which it probably wont, the crank may be a bit longer and the frame might not be able to take the torque if the engine its bolted at iffy locations. in that case i thought of an adapter plate. that way i could adjust not only the fit but the depth of the crank to match the old.
Old 08-02-05, 09:50 PM
Join Date: Jul 2003
Location: ill.
Posts: 68
other info i thought of is i put a 4hp carb standard diaphragm on the 5hp yrs. ago and it works fine. i have also interchanged some parts on 8 and 12hp engines i have.
Old 08-03-05, 12:09 AM
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Just about anything is possible. If you don't mind the expenses and effort required to make this work, go for it. There are 7 hp engines made for push mower applications that will fit right in place of your old engine. You might have to change throttle and engine brake cables to make it work properly, but it can be done.
Old 08-09-05, 03:38 AM
Join Date: May 2005
Posts: 39
Outfits like Tulsa Engine Warehouse have line drawings of different engines. Just filnd out what you have for shaft diameter and length and mounting bolt circle, and find a larger engine with the same pattern.

I wanted to put a bigger motor on a 5hp Ariens Snow Blower and got all kinds of conflicting advice - including a dealer service manager telling me it was "impossible".

A 7.5 hp B&S OHV Intek Snow fit straight onto the mounting holes and had the same shaft location and diameter as the old Tecumseh L head. So while forum advice will be divided into yes, no, and maybe, you won't know until you look at the drawings - or call the engine manufacturer.

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