You should be able to find a replacement engine at northertools.com....the Model is Horse ....DOM might be 9th month 1974 ???? Your 6hp tecumseh used just the crankshaft to power the tiller ,if it had a reverse that used the camshaft also ,you would need to be sure that the replacement engine had two shafts to power fwd/rev also.
Good Luck Jim

A Horse is a Horse, of course, nothing but a horse! and, why go bigger/ That 6 h.p. did the work! no need to go bigger! at more expense!
Rustyj

The size of garden that I till is rather large and would like all the power I can get. So how do know what the replacement engine is? The current one is dead. It has zero compression. You pull the handle and the just spins and slowly slows down. It is a rather old engine and worked well past its time. I hope to take it off this week and tear it apart to see what broke. My guess is the valves. It did make a loud noise and then just spin down to a stop.

"It did make a loud noise and then just spin down to a stop"
Ouch! Sounds like the old girl slung a rod.
More than likely your engine is an H-60, or possibly an HH-60 if cast iron.
Too bad Tecumseh doesn't make that engine anymore, but another 6 or 8 horse Tecumseh or Briggs should bolt on fairly easy.
Go to smallenginewarehouse.com, they sell a Tecumseh 8 horse that should be a direct swap, and their prices are great.

Set the old engine on a flat surface-measure the distance from the plate to the center of the crankshaft. Be sure the engine you buy has the same measurement! Also, the same length of crankshaft!
and, more h.p. won't be any more efficient for tilling any areas, big or small! Its not how fast you can go, its how well the engine runs, how well you care for it, how well you maintain it, whether you check the oil before and after use, changing it frequently!
Your old engine broke the connecting rod--probably because nobody bothered to check the oil level before they started it! ("Oh, it was full when we bought it 30 years ago!") Seems those kind of machines don't get much, if any, maintenance, over the years!) I've gotten engines with the oil drain plug so covered with dirt, you'd know it hadn't been out in a long time! ("Oh, is that what that plug is for?")

The best deal, is to google "small engine warehouse" and
click on some of the results. Most of them have "horse"
engine replacements, and at a much better price than you
could locate anywhere else.

Fish

I have an HH60 removed from 1983 Troybuilt used most years for very small garden. Installed a Honda, same horsepower for no other reason than I now have all Honda engines and a commonality of spare parts. HH60 ran well and is boxed-up $50 & pay shipping

For the money the HF 6 1/2HP engine on sale for $99 is hard to beat. I've had one on my horse for 5 yrs now and it's still going strong.

Mike

mia2ofus, i am assuming HF is Harbor Freight? The one you purchesed, is it item#69730? My HH60 shot craps today and am wanting to replace the engine. Did this engine mount right up or did you have to do modifications? Thanks!

rootcause, can you tell me what Honda engine you replaced your HH60 with? Thanks.

I did the harbor freight engine too a couple of years ago. I believe it went right on. I think that I was able to use the same pully, but I think that I had to find another bolt to attach the reverse disc (different threading).

edit: btw: I was just using it today. It is going on its second full year. It fired right up as usual and ran fine while I tilled my 30' x 35' garden. I just set it to run full speed. I have detached the throttle cable because it needs to be longer to fit the new engine. I almost never needed to run the engine more slowly anyway, but I was also looking on line today and found a 6' cable that I might get (but maybe not).

Depending on how old your machine is--there is a shaft that protrudes from the gear case cover, that the reverse pulley fits onto. If it isn't in it/ on it, and the shaft isn't there, don't buy that engine. Contrary to what everybody sez, You should buy an engine locally, so you can see that shaft, or not! No use having to pay for shipping, and/or a return fee. Been a while since I worked on one, but, I have the illustrated booklets that explain the process. You should contact the Company to see if those booklets are still available! HTH: Rusty Jones

I should say this: Your gear case may fit the newer engine--or not! If it does-yer home free. If not---- RJ

Thanks for the input Rusty, appreciate it! Tried the Company and they don't seem to have the booklets that you talked about. Couldn't get you to scan the pages you think I need and email them to me could I?

The model and serial numbers plate is all faded. Pretty sure this is an older machine. I am attaching a photo if anyone can give me an idea of year or model. thanks