rear engine snapper info
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Arwing64
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Swapping a smaller engine with a much larger engine may sound like a good idea, but you may run into problems. First off, an 8 HP Briggs and an 18 HP HP engine is incredibly different in size, weight, and power. Is is possible to do this? Yes.
For a rear engine rider, the engine is usually tucked into a small compartment just big enough to house the engine. This of course varies from model to model. A much larger engine may not even fit into it, and the bolt pattern on the base plate would obviously be different. The shaft size might be different too. The 8 HP Briggs might have a 3/4" shaft while the larger 18 HP might have a 1" shaft.
The transmission on the tractor is most likely only able to handle 8 HP. So if too much of a load it put onto it, you might bust the transmission. Although this may not happen under normal conditions, it is still possible that over time the transmission may become too overloaded.
There may be some components if the engine that would not work with the original electrical setup. The 18 HP may have a fuel solenoid, a small device at the bottom of the float bowl designed to cutoff fuel when no power is going to it. The 8 HP engine probably did not have a fuel solenoid. Your original engine may have had an electric start and an alternator to charge it. The 18 HP most likely has the same thing, so the setup is simple there. The original batter may not have enough cold cranking amps to power the starter motor on the new engine. The battery may have to be swapped with a more powerful one. Test it out and see if it might work with the original battery.
The throttle and choke linkages would have to be modified for the design and orientation of the carburetor for the 18 HP engine.
The critical thing is making the 18 HP fit within the space provided AND making sure the shaft is centered perfectly at the same time.
An 18 HP engine can either be a single cylinder, an opposed twin, or a V-twin. Can you tell me what engine it is?
For a rear engine rider, the engine is usually tucked into a small compartment just big enough to house the engine. This of course varies from model to model. A much larger engine may not even fit into it, and the bolt pattern on the base plate would obviously be different. The shaft size might be different too. The 8 HP Briggs might have a 3/4" shaft while the larger 18 HP might have a 1" shaft.
The transmission on the tractor is most likely only able to handle 8 HP. So if too much of a load it put onto it, you might bust the transmission. Although this may not happen under normal conditions, it is still possible that over time the transmission may become too overloaded.
There may be some components if the engine that would not work with the original electrical setup. The 18 HP may have a fuel solenoid, a small device at the bottom of the float bowl designed to cutoff fuel when no power is going to it. The 8 HP engine probably did not have a fuel solenoid. Your original engine may have had an electric start and an alternator to charge it. The 18 HP most likely has the same thing, so the setup is simple there. The original batter may not have enough cold cranking amps to power the starter motor on the new engine. The battery may have to be swapped with a more powerful one. Test it out and see if it might work with the original battery.
The throttle and choke linkages would have to be modified for the design and orientation of the carburetor for the 18 HP engine.
The critical thing is making the 18 HP fit within the space provided AND making sure the shaft is centered perfectly at the same time.
An 18 HP engine can either be a single cylinder, an opposed twin, or a V-twin. Can you tell me what engine it is?
Carscw
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The two problems you will run into are.
Shaft size on the 18hp is 1 inch. Easy fix.
I paid $20 to have a shop bore out the drive plate. Then bought a pulley from tractor supply to drive the blades.
The exhaust. If it's a single cyl then no problem. If it's a twin cyl you will have to turn the pipes up or install the engine so the muffler hangs off the rear. Then you will not be able to stand the mower up.
Shaft size on the 18hp is 1 inch. Easy fix.
I paid $20 to have a shop bore out the drive plate. Then bought a pulley from tractor supply to drive the blades.
The exhaust. If it's a single cyl then no problem. If it's a twin cyl you will have to turn the pipes up or install the engine so the muffler hangs off the rear. Then you will not be able to stand the mower up.
