I am from Australia and am looking to call on your collective wisdom to assist in the repair of an 8hp vertical shaft briggs & Stratton engine that punched the connecting rod out the side of the engine case.
What engine sizes (ideally larger) share the same physical mounting hole locations, and overall external physical dimensions.
Ideally i would like to install a larger horsepower engine, so long as it is the same physical size as the 8hp vertical shaft engine, or to repair the 8hp 319cc engine with your suggestion of the general replacement parts that i am likely to need.
I have never needed to know anything about these engines, and even though i'm fairly good with repairing engines, i have never had to repair a Briggs & Stratton, so in that respect, i am a newbie to this.
Lets start with the model number information of your current engine. There are other engines that you can use, but we will need to get more information to give you the best options.
While we all like more horses, all mower engines spin at around the same speed , 3500 rpm so a bigger engine will not make the mower go 1 mm / minute faster.
If you cut long grass or have a very hilly yard then it will be a distinct advantage as the engine will not bog down.
Aside from the existing engine numbers it would be immensely helpful if you told us what it is going into .
A lot of bigger engines will just not fit into smaller mowers.
I am currently having a devil of a job trying to fit 15Hp intek into the space that a 13 Hp Diamond plus went into because the crank is bigger and fouled on the steering gear of the Greenfields Anniversary model.
When we replaced the 13Hp Powerbuilt engines with the 11 Hp inteks in a bunch of Rover Rancher III we had to turn the engine around and change the fuel tank as the longer cylinder overhung the front of the mower.
The 13 Hp Power builts that were servicable went into some Rancher II's replacing the 10Hp engines and we had to fit shorter belts as the longer engine would not side far enough forward to get the belt tight.
There is a lot more to it than the bolt pattern and length of the engine.
Lets start with the model number information of your current engine. There are other engines that you can use, but we will need to get more information to give you the best options.
I had a mower shop modify the 8hp crankshaft so that the engine would mount up to the blades. The engine had to be turned around 90 degrees, allowing it to be fitted onto the mounting location of the original 5hp engine.
I have been told that the engine is around 20 years old, and you cannot get parts for it anymore in Australia, hence why i would like to have more engine options, ideally, more powerful engine options, as even the 8hp engine isn't powerful enough to mulch long palm fronds.
Where do i find the model number on the engine, as i cannot readily see it?
Your collective help would be appreciated greatly.
Most likely location for the model number on that engine would be under where the throttle control is located, or down the side of the blower housing opposite side as the air filter.
First thing is you can get parts for those engines.
I get mine from Jacks Small Engines who also sponsor this site ( amongst others )
Your model code and type numbers will be on the engine cover directly over the spark plug, stamped into the metal which makes them a little hard to read.
Use those numbers on the USA Briggs & Stratton web site to download the engine parts diagram.
It will automatically send you to the Australian site which is about as much use as tits on a bull.
When you get there select North Amercia as the location and you will be in.
Any single side valve Briggs engine will bolt right up.
Good luck getting the blade carrier off the shaft.
Downside is they don't make side valve engines any more.
I have put a 13 Hp into one of those , went strait in sideways
We had to drill some new holes and I used an engine mounting plate from an old Murray ride on to stiffen up.
The fuel tank got hung off the feed chute which was a bugger when you had to open it up to clear a jamb but it meant I could put on a fuel filter and tap.
No good going much bigger than 13Hp because the output screen will bend before the engine stops with the 13 Hp so a 10 or 12 might be the way to go.
Most old mower repair shops will have a stack of old side valves they keep for spares because no one will buy a ride on now days with less than 10 redundant Hp.
If you are cutting palms regularly then keep the blades very sharp and grind the blade to around 30 deg which will serve you very well provided you don't go tossing dead dry gum branches in there .
Can you post photos of your Rover Shredder Mulcher 13hp conversion, and the """murray plate stiffener", and where i can get this item, as i want to replicate your exact engine conversion.
How do you get the blade carrier/blades to mount up to the larger diameter shaft, which i assume is 1" diameter?
I have the model number for the 8hp engine: 90702 1203 01 81080611 if that gives a better picture of the type of engine i have.
Your 8 Hp should have a 1" shaft. All the ones I have worked on did.
I sold that Rover a long while ago, got a slightly latter model now waiting for an engine swap.
When we were running the 13 Hp anything too big down the chute jambed the blades against the finger screen on the output and usually bent them.
The bolt holes are not symetrical so if you rotate the engine you have to redrill the mounting holes .
However the new holes end up being very close to the old ones so we welded the Murray plate under the platform as it takes the full weight of the mower and the vibes from the machine working.
Any plate of steel will do, it just happens that the Murray was in the graveyard at the time. I was going to use the plate from one of the Rancher II's but that mower was slated for repair.
Currently running a Masport , Granberg & Allpower.
We do a lot of shredding as the landlord grows olives and christmass trees.
Add to that there are acres of lantana, blackbury & private that needs to be cleaned up fairly regularly and that dose not take into account ferral natives.
So If the 8hp engine that is currently mounted 90 degrees to the original 5hp engine, then the 10hp, 12hp and 13hp engines should bolt straight onto the red mulcher/shredder frame, but your advice is to attach a steel plate underneath the sheet metal (and in the area where the blades spin) to strengthen the engine mounting area? If i have understood your explanation correctly.
A 10 or 12 should go directly in where yours sits now and bolt strait on.
The 13 fouled because the case was bigger.
The mounting holes were in the same place so it was either rotate the engine or change the feed chute.
The bolts holes are not symeterical around the engine shaft and the engine shaft has to stay in exactly the same place.
So we rotated the engine.
This meant drilling new holes which were very close to the old holes and would have weakened the engine mounting.
Remember every time the blade smacks something in the hopper the engine tries to rotate in the opposite direction to the blade rotation.
Thus the strengthening plate.
If you put in on the top , which is easy it will raise the blades by the thickness of the plate.
If it goes underneath the blades end up in exactly the same place only the clearence between the top blade & the body is reduced.
If you don't drill new holes no need for the thicker mounting plate unless you see it starting to crack.
Briggs did what most makes did.
Started with a bore & stroke for one series then either stroked or bored it go to the next series
Within a series they used various devices like a smaller carb, or smaller jets or a restrictive manifold to get the 1/2Hp incriments
The first number is a 6 digit number so your current engine is 091702 with the 09 being the displacement in cu in.
Usually within a single series there was usually a 2 to 3 Hp range.
This will explain it better than I can
And you need t remember that your shredder uses an obsolete engine so you are looking at the differences between one obsolete engine and another obsolete engine.
Could it be assumed that there should be a lot of 12hp engines floating about as they would be the more common engine size used on ride on lawn mowers?
