Heymow - Lawnmower Racing Forum

Engine Help => Briggs Flathead => Topic started by: dragon45895 on April 23, 2010, 11:05:47 pm

Title: is it possible to convert a vertical shaft oppossed to a horizontal?
Post by: dragon45895 on April 23, 2010, 11:05:47 pm
I have a 12.5hp horizontal briggs opposed engine that smokes like a freight train, and i recently aquired a 14hp vertical shaft opposed twin.  both are 40ci blocks, and the 12.5 is complete.

is there a way to covert the 14hp to horizontal using parts from the 12.5?  has anybody done that  before? 

if your wandering why im asking, its because my beloved snapper i used for years is fouling plugs faster then i can replace them :(, and i cant find any reasonably priced horizontals in my area.

any help/info would be awesome :)
Title: Re: is it possible to convert a vertical shaft oppossed to a horizontal?
Post by: Running on Empty on April 23, 2010, 11:24:06 pm
Are you going to use it for racing?
Title: Re: is it possible to convert a vertical shaft oppossed to a horizontal?
Post by: dragon45895 on April 23, 2010, 11:41:47 pm
Not this one, its to revive my grass cutter, have other engines for racing, but this is the only place i could think of to find info on converting this thing. 
Title: Re: is it possible to convert a vertical shaft oppossed to a horizontal?
Post by: Running on Empty on April 23, 2010, 11:51:01 pm
You would probably be farther ahead just buying rings and rebuilding the motor that is in your grass cutter.  I believe some parts are transferable between the horizontanls and the verticals, but not all of them.  Either way hone the cylinder, clean the block and heads up good and get some new rings and maybe a gasket kit and you will be on your way.  You would have to do this anyway is you were going to build one good motor out of the two you have.

Am I making sense or totally missing what your going after here?
Title: Re: is it possible to convert a vertical shaft oppossed to a horizontal?
Post by: dragon45895 on April 24, 2010, 12:19:03 am
i would be happy to rering the engine, but it has a good bit of what i call "ring rot", in other words, it would need bored, and over size pistons/rings installed.  hense the reason i was after converting the vertical.

Title: Re: is it possible to convert a vertical shaft oppossed to a horizontal?
Post by: Running on Empty on April 24, 2010, 02:43:04 am
I dont think I would go so "extreme" until you actually pull it apart and look at the cylinders and mic them.  You may find a cracked or broken ring.  If you need oversized rings it is not a big deal.  Bottom line is you need to tear that motor apart and see whats going on,
Title: Re: is it possible to convert a vertical shaft oppossed to a horizontal?
Post by: Huffy044 on April 24, 2010, 08:19:39 pm
Old Goat does it to Briggs single OHV.s I have have spent some time following him around the track, I'd say he is pretty successful-send him a pm
Title: Re: is it possible to convert a vertical shaft oppossed to a horizontal?
Post by: THawley08 on April 24, 2010, 10:03:27 pm
Blocks are the same just the pan, crank, and cam are diff. I believe
Title: Re: is it possible to convert a vertical shaft oppossed to a horizontal?
Post by: FlatheadPuller on April 25, 2010, 06:02:22 pm
All parts interchange unless going from psi to splash. The only thing one would need to do is also change the crank if going from horizontal to vertical. If going from vertical to horizontal and not using it on a specific piece of equipment you do not need to worry about it. A vertical crank is 2-3 inches longer on the pto end then a horizontal. When going from a vertical to a horizontal you need to change the sump, side cover, dipper and induction. Same thing when changing from horizontal to vertical.
Title: Re: is it possible to convert a vertical shaft oppossed to a horizontal?
Post by: dragon45895 on April 25, 2010, 09:20:55 pm
All parts interchange unless going from psi to splash. The only thing one would need to do is also change the crank if going from horizontal to vertical. If going from vertical to horizontal and not using it on a specific piece of equipment you do not need to worry about it. A vertical crank is 2-3 inches longer on the pto end then a horizontal. When going from a vertical to a horizontal you need to change the sump, side cover, dipper and induction. Same thing when changing from horizontal to vertical.

Thank you for this information, this is what i was after!.

my next question is:  would the sump, side cover, dipper and induction off of the 40ci opposed, fit a 18hp 42ci opposed?  i do have an 18 availiable, and it would be a nice power boost for this machine, its in better shape too i might add, just had new rings and such installed
Title: Re: is it possible to convert a vertical shaft oppossed to a horizontal?
Post by: FlatheadPuller on April 25, 2010, 09:27:27 pm
yes
Title: Re: is it possible to convert a vertical shaft oppossed to a horizontal?
Post by: dragon45895 on April 25, 2010, 09:44:21 pm
Very cool, will have to go pickup that engine then!  im glad these things interchange as good as they do!
Title: Re: is it possible to convert a vertical shaft oppossed to a horizontal?
Post by: Rooster on April 25, 2010, 09:44:35 pm
There are some differences in how the oil passages are drilled in the horizontal and vertical blocks.
The 12.5 is not much different than the 14. The 42 cube 18 however will have longer stroke as well as bigger valves and different heads, so you would definitely want to use that block & heads, and the carb is bigger as well.  Yes the sump and side cover will bolt on, but be sure to check the oil passages in that block, might need some changes.
Title: Re: is it possible to convert a vertical shaft oppossed to a horizontal?
Post by: outlawmower on May 05, 2010, 09:26:35 pm
Yes you can convert these motors. Just shoot Flatheadpuller a PM and he can give you some more details.