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Briggs motor swap

1479 Views 11 Replies 7 Participants Last post by  Tractor-Holic
I have a Noma lawn tractor with a briggs 18hp twin that's locked up. I happen to have a 12hp single cyl. briggs setting under the bench. I'm wondering how big a conversion it would be to put this 12hp into this no-account Noma tractor. Shaft size difference, mount difference and-so-on. If anyone has doe this I'd appreciate some input here. This was one of those rear wheel steer outfits. I've already swapped out the rear-end on another occasion. It's only front wheel steer now.


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If I have your model,type and code numbers for both engines,I should be able to look it up.
I'll get them pronto

35077 / 1034-A1 / 95022411
Model / Type / Code

283707 / 0153 01 / 9502234E

Sorry, i have no clue how big of a swap it would be (probably not that bad, if you have a welder and a little time).

But, by the codes you provided of the two engines, they were made the exact same year, just one day apart! Now thats a coincidence if i do say so myself.
the codes you provided of the two engines, they were made the exact same year, just one day apart! Now thats a coincidence if i do say so myself.

I didn't notice that . . .it is very interesting.

I think in Northern Tool's catalog they have a chart with all the dimentions and specs on engine mount bolt patterns and crank length ,etc..So does the website under "tech info" in the engine listings..

I'm thinking those engines are probably swap-able without too much hassle myself..most 12-20 HP engines share similar mounting and crank PTO's,since many lawn tractors use the same chassis (or nearly so),with larger engines twin cyl.engines,and hydro trannies
VS single cylinders and manual trannies on lower end models...
From what I've found the shaft diameter and length are the same 1" X 3 5/32".
I think I'm going to go ahead with it. If I have to cut holes in the frame for mounts so-be-it. There might be a little wiring to contend with but I'm a wire guy by trade so It's not a problem. I'm betting I won't even have to cut holes. Others here have said they use the same frame for a number of different models so I'm betting this will work with minor modifications.

Thanks guys,
Dropping from an 18 to 12 HP may cause some attachments to be under powered. If your running a 60" mower deck that 12 HP may struggle in tall grass.
Before you start to reinvent the wheel, you may want to open up that Vanguard, and see what is required to repair it. A good running Vanguard is going to be a much better option that even the best running 12 HP single.
I picked up a Toro for free once that was "locked up" and hauled it to a friend's house. We took the spark plug out (to free up compression) and tried to turn it by hand. Suddenly it freed up, we squirted a little gas in the opening, put the plug back in and it fired right up. Sold it for $200 later in the summer. Give it a good check before giving up on it, as per rscurtis above. Going to a 12 is definitely going to reduce power.
Yes,it wont be a powerhouse,but it'll probably be good enough to get him by, until a better engine or tractor comes along!..
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