71 800 special engine options.

[Tripwire 1]

So the tractor has the original 8hp Briggs currently. I’m thinking about swapping something with more power for mowing and such. What would bolt directly up to this tractor and require the least modification? 

[Stepney 2,354]

The B&S 8 should have enough grunt to mow lawns and the like, but it would be getting on in years and they dont age so well as a Kohler IMO.
You could very easily drop in a 10-16hp Kohler. One from a WH would be bolt in and go, a K series from another make may require small adjustments. (A junker doner would make it a breeze).
Your B&S will have a 1" crankshaft. So you will need the larger 1 1/8" drive pulley, and if you want to run implements, you'll need a PTO clutch and associated hardware. Very easy to do once you have the parts. I just converted a Raider today.

I guess you could go with newer alternatives .. but personally I despise most of today's options, and good Kohlers are plentiful. 

[ebinmaine 72,681]

Agreed.

 

Find a Wheelhorse for parts and use that as your donor.

You'll have all you need right in your hands.

 

I'd add to what @Stepney stated by advising a 12 horse or larger.

There's a noticable difference in power/torque between 8 and 12.

Not to much between 8 and 10.

 

[ebinmaine 72,681]

Of course another option would be to just go find a decent running 12 horse machine and use IT for mowing.

Keep the 71 8hp for puttering around on.

Add to the herd. Save all the work.

 

Down in your PA area there's a ton of horses for low money available.

 

[edgro 680]

Agreed. I had to buy 3 "donor" tractors to get one worthy of being parted out

[Tripwire 1]

So I’m going to do a compression test to the 8hp Briggs. What’s a good psi range for these engines? 

Edited April 30, 2020 by Tripwire