1872 engine swap question

[cwcub]

Is a m20 from a 2072 A direct swap for a 1872 with a m18. I'm looking at remanufactured long blocks and was thinking why not go with the m20 instead for an extra 100 bucks. will the manifolds, carb, starter bolt on the m20. I imagine jetting would have to be changed. anything else?

[Tom Scott]

Just need the pto for a 20 hp, it is has a larger crank snout diameter. Yes, if you have access to a Mag 20, absolutely!

[dag1450]

Yes pto is different.......but hold on...there are a couple more! I found the carb to b different......i could not get my 20 to run (good) on the carb from an 18. a few years ago i needed to work on the 20 carb ...so i bought some time and robbed a nice newer carb from another 1811 i had.....me or the 20 were not happy.
Starter might bolt up....but the electrical connection is in slightly differt spot....not a deal breaker.
Some sheet metal is different.....will they b a show stopper...idk. the 20 is maybe 1/2" wider. flywheel shroud is different. Sides have different part number..and i just found this little detail this spring. The lower muffler box tin from the 20 did not fit on the 18......it was wider to the point i had take it off and put the right one back on....and believe me....the little bolt down by the starter is not too fun to do twice! Parts look up shows same part number so...idk
Just on the pto detail.....i personally would not bother. Just call me "Debbie downer". good luck

[dag1450]

I forgot to ask....where r u looking at this block? I did see one outfit that was doing that....and it was tempting.
While u r doing this swap.....if your fuel pump is older..that is a must do. My starter stuck when cold....so i bought that. u will need several gaskets...muffler, intake, probably oil filter block connection...and dont forget the all important turbo encabulator.....that is also exclusive to the mag 20. If u r not familar..look it up...u may b able to install one on the 18 also.

[BigMike]

Dave, what is the status of your rebuild?

[dag1450]

Mike....so many questions......i will answer over on my topic

[dag1450]

This is the 20 lower muffler box. It was cut and made wider

IMG_20160522_085843345_HDR.jpg (2.93 MiB) Viewed 4889 times

[cwcub]

Always hidden details. I will stick with the M18. I'm sure i can find a couple ponies somewhere.

[Tom Scott]

My bad, I didn't think there were differences in the muffler box sheet metal. The carb I knew, but glossed over the long-block part. I think of replacement engines as whole pulls from a scrapper where I would get the engine shrouds, flywheel, carb, etc.with it.

I checked the diagrams, the starters are different. The 2072 starter has a different armature, so they must have given it more umph. Without a complete donor motor, this would be an expensive swap. Sorry I answered less thought than I should have!

I too am curious who is offering complete rebuilds as a package.

[dag1450]

I'm under the weather this weekend so I have a lot of time to think about your project.....and all mine . Corey....just make sure they ask u about the crank specs.....so your PTO will work with out issue.

[cwcub]

That's ok Tom. Thats the beauty of a forum. many brains and experiences! Kustom Lawn and Garden has these kohler long blocks but you must send in a core. I just googled rebuilt Kohler. I think they are in Ohio. They advertise 30+ years rebuilding K series and the M's Claim to have worked out the failure of the governer gears and some other things "better than new" They are cheaper than the repower OHV kits by about $500 I am seriously considering this route if I don't gernade my engine by thew end of the season. Not uncommon to be mowing in near 100 degree weather. been running ams oil small engine oil for a couple years in the 1450, lower oil consumption seams to do well. Any way that's my plan for now for the 1872