312-8 Engine Repower

[LFB 12]

Glad to be a new member!

To repower or to buy new, that was the question. The ole Kohler was worked on once and lasted a while before it would now have to go into a whole “total rebuild”
It was hard to find any local dealers that wanted to do the work on a 39-year-old engine, and being that old, they basically suggested that I just go buy a Home Depot / Lowe’s model economy series and call it a day. WOW!

Out of curiosity, I did visit several authorized dealers of some top brands and in all honesty, I could not find a unit that I really liked. They were all “lawn tractors” as to where the Wheel Horse is first a “tractor” then by adding the deck it becomes a machine that can mow the lawn. The only models that seemed to be built like the Wheel Horse were on the 7k-10k price range. They just don't build them like they used to.
Not to mention, some had plastic transmissions; no, no, no! So, I made the decision to repower.

Yes, it is an investment, but that tractor has been good to me for 39 years and I just could not be comfortable seeing the whole Horse go out to pasture.

I contacted Repower Specialists and they set me up with their Honda GX630 kit for replacing the Kohler M12.
The install was not too bad, but I did run into a few minor hiccups with wiring (which they sent me a custom harness) and some PTO bracket clearance issues with the muffler.
I found fixes for all.

With that said, I wanted to document the install of the repowering of my 1987 Wheel Horse 312-8 tractor (bought new in the fall of 1986) with the new Honda GX630 engine kit.
I saw a lot of videos out there for engine replacements, however none were going to use the PTO and therefore they were dropping in all sorts of engines for mud bogging and such.
Even though this is a 312-8, I believe the install process, and some issues I encountered, along with the fixes, may apply to other Wheel Horse models. I hope this video helps if you decide to repower.
Link: https://youtu.be/KPl3smQl9cg

[ebinmaine 70,524]

 

 

Long history!!!

 

 

Glad you had the sense to repower that gem!

 

 

 

[Sparky-(Admin) 21,997]

  I kinda zipped thru the video…but well documented! 
  Nice Install as well 

 

 

[Achto 28,681]

 

Nice to see you keeping the ol' girl going.

[SylvanLakeWH 27,376]

 

[oliver2-44 10,323]

Nice repower

 

Don’t chunk that M12. Someone here may need some parts off it. 

[gwest_ca-(File Mod) 11,234]

Nice installation.

When they started using the Command engines the drive pulley was not tight to the crankshaft laterally and the set screws would allow pto pressure to move the pulley inward resulting in a slipping pto clutch.

Their fix was to add a spacer behind the drive pulley. Just a heads up.

 

[mrc 873]

great video, nice job!  

[CCW 1,333]

@LFB  I did the same last year with my 87 312-8.  Here are the two links to my process. 

 

312-8 Repower Update - Engines - RedSquare Wheel Horse Forum

 

312-8 repower - Page 2 - Engines - RedSquare Wheel Horse Forum

[953 nut 57,740]

14 hours ago, LFB said:

The only models that seemed to be built like the Wheel Horse were on the 7k-10k price range.

It may be 39 years old but it looks like new and now runs like new too.                            Factoring in inflation your $ 2,500 purchase in the fall of 1986 would be $ 7250 today so IF today's offerings were comparable to a Wheel Horse the price would be about the same, but they aren't.

[LFB 12]

1 hour ago, CCW said:

@LFB  I did the same last year with my 87 312-8.  Here are the two links to my process. 

 

312-8 Repower Update - Engines - RedSquare Wheel Horse Forum

 

312-8 repower - Page 2 - Engines - RedSquare Wheel Horse Forum

I actually read through your thread about a month ago and it was because of your post that I knew it was the right move to make. My Kohler was acting up the same way yours was with burning oil and such. Had new piston rings valves etc.. installed, but there is never any guarantee that the work done will correct the issues unless one does a full blown rebuild which requires boring the cylinder new crank / cam and it seems to open Pandora's Box... The new tractors don't have anything close to the "tach-a-matic" system and when I asked how easy it was to remove the mower deck. all the sales folks, said. well.... THANK YOU again for that post you did on your repower as that made the decision to repower a solid one for me   

[LFB 12]

7 hours ago, mrc said:

great video, nice job!  

Thank you. Figured some folks might want to repower and the video would be a good reference for them, hat could possibly help with their specific Wheel Horse model. Plus it slowed me down in the install process which is good for me as sometimes I can rush along and then later wonder, did I tighten those bolts??? LOL

[Lee1977 7,024]

We have been repowering for years. I put a Briggs Vanguard in a C-120 8 speed thirty six years ago. There's know room to spare but it's in there.

[kpinnc 13,645]

On 4/10/2025 at 5:44 PM, LFB said:

Yes, it is an investment, but that tractor has been good to me for 39 years and I just could not be comfortable seeing the whole Horse go out to pasture.

 

Now you need to find a 48 inch deck because you have plenty of power for it. 

 

Well done on the repower! Great to see you keep her going!