They are everywhere. Just look for 2 and 3000 series cubs.

The 20hp is not any easy engine to obtain unless you come out of pocket. I feel that me having my motor apart and with me grabbing a vertical shaft 20hp mag tomorrow i should be in good shape. I was just wondering if anyone has found a video or step by step procedure of how to convert the vertical shaft one over to a horizontal one? I will then most likely work over the winter in rebuilding the original 20hp mag horizontal. I appreciate your help though guys.

It's a very involved conversion. Ol'George has done it, but it's not easy. I think he had to machine some parts to make it all work.

As in "Ol George"? A check for the name on the member list but I don't see it. Maybe it's just me or it's spelled differently. Let me know thanks guys. And also guys if I go through with this I will make sure to post as much information as possible so that others can use in the future.

http://www.onlycubcadets.net/forum/member.php?u=1190

His profile. :beerchug:

Ok this is from the memory of an old fart:
I have no experience with mag 20's only mag 18's.
On the m-18, I needed a good crankshaft, so I used the vertical one as my horiz was junk.
I had to cut it off and machine (lathe work) it to 1-1/8" dia. and make a short bushing on the 1" undersize section @ the end of the clutch bearing area.
Then drill/tap the end of the crank for the pto clutch retaining bolt. as it was a vertical and much too long, and with it shortened, the thread was gone .
Also a captive keyway had to be milled in the crank for the key that drives the pto clutch.
IIRR the M-20"s are 1-1/4" diameter not sure as I have said,I have no knowlege of them so that might not work without measuring and doing figuring.
M-18's are 1-1/8 so this m-20 crank machining might be very different or not be feasible at all. :bigthink:

The block was not drilled for a dipstick tube, so I had to set it up on my B'port mill and drill it @ a compound angle with a special 16" drill.
Can't remember the size but it was over 5/16, maybe 3/8 Dia.
Then drill/tap the dipstick tube retaining clip.
Then I had to drill the oil passage that was not drilled in the block where the suction tube mounts for the oil screen in the bottom of the sump
( again Bridgeport work)
Also the cup plug had to be pressed into the block, to block off the new drilled oil passage hole @ the pto cover mating area, to duplicate the factory machining.
There are 2 different diameters on that modification, to contend with.

Then there are 2 gravity oil drain back- to- sump holes, not on horizontal blocks
(one in each cylinder) that are drilled on vertical blocks that have to be plugged,---- if you don't plug them, it will flood the valve/spring chamber and it will consume huge quantities of oil.
I turned up aluminum plugs for this, with an interference fit and pressed them in the holes and headed then, so they would stay put and be retained by the cylinder spigot when assembled.
You will have to use your horz. oil screen pickup box,
as well as your pto end cover.
Prolly more but I can't remember just now.
Like I said in the old post referenced to,
it ain't a bolt together and go.
And without having done a mag 20, all bets are off.:bigthink:
This should answer your personal message as well as answer interested others.
I did it as a challenge and the engine is running well today, @ least 800 hrs later.:beerchug:

Thanks Ol'George. The information that you have provided is huge and important to me and others who may venture in doing this task. Thank you again for your time and knowledge. I am sure that there are others out there that have done this and will hopefully chime in and fill in any gaps or pointers that may have been missed.

Thanks
Again

Jay B

Sorry to necromance this thread, but do you know if a KT-17 II horizontal crank is the same as an M18? And if the closure plates are the same?

I.e could I take parts from a KT17 and use it to convert an M18 from vertical to horizontal?

You can use the series 2 closure plate, yes.
Even a series 1 closure will work, but it needs machined for the oil pressure relief valve spring pocket.
IIRR the taper on the magnum flywheel is larger than the series 2, and so is the oil seal, so cranks are not swap-able.
If you have a lathe and mill and know how to use it to machine the block,
just knock yourself out, as I did, but if you don't have the equipment, spend maybe $100 or less and buy a mag horizontal block on ebay.
A much less expensive, and way easier way to do the conversion.
And if you do buy a block, make sure you buy both sides of the block as a set, because they are machined as a set.
Some idiots sell 1/2 of a block, because they don't know that.
It would be like buying a connecting rod & cap from different sources.:bigeyes:

Thanks George, that’s very helpful! I do have access to a machinist with a mill and lathe. It doesn’t look that awful to me, but I’d prefer to do as little cutting as possible.

I found a whole MV18 for 150, so if I can keep the modification costs under a couple hundred I wouldn’t be doing too bad I guess. Would be nice to see what shape the innards were in anyway.