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.
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 www.surpluscenter.com 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.
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.