engine rpms

[john2189]

How much over the 1800 rpms would be safe without doing any damage? Ive done a full tune up , adj valves etc and I think a few more rpms would help run the woods 59

Some one on here said that rpms makes hp and ____?______ makes torque

[Randy Tuura]

How much over the 1800 rpms would be safe without doing any damage? Ive done a full tune up , adj valves etc and I think a few more rpms would help run the woods 59

Some one on here said that rpms makes hp and ____?______ makes torque

I'm not an engine expert, but there are a couple ways to improve the mowing with a Woods 59. I have one and use it every week.

First on my list of things to do to improve cutting is to make sure the blades are sharp.
Second is to mount it with the proper "trim" - leading edge slightly lower than trailing edge.
Third, check your pulley size coming off the PTO. If the pulley is from another implement, it might be smaller. It would have more power but less RPM on the blades.

There are several things to do to improve cutting before trying to re-engineer the engine.

Just sayin.

[Eugene]

Increasing engine RPMs will increase the mower blade feet per minute and also increase the tractor's ground speed. If the mower is set up correctly and correct pto pulley size, nothing gained.

[Scrivet]

Along with what's already been mentioned add 3 well greased easy turning spindles and 2 smooth running mule drive pulleys. That's ten bearings you have to spin before you ever touch the first blade of grass. One running rough will eat a pony, a couple running rough will eat a horse(power) or two.

[Matt Kirsch]

Torque and RPMs make Horsepower.

Torque X RPM / 5252 = Horsepower

As the RPMs rise in an engine, torque rises, hits a peak, and then starts to fall off.

I think peak torque on a Cub engine is around 1500-1600 RPM if I'm not mistaken.

After 1600RPM the engine makes more Horsepower, but only by virtue of the RPMs rising faster than the torque is falling. Even that has a limit, and Horsepower starts to fall off at around 2000 or 2100 RPM, where the last Cub engines were running.

The later Cub-engined tractors were geared "slower" to take advantage of the increased HP at higher RPMs. They traveled the same speeds but only by virtue of the higher RPMs of the engine.

More RPMs without a gearing change is just more noise and a slightly longer run into the tall grass before the tractor begins to lug down. Normally the tractor will "seek its own level" where ground speed, mower speed, and available power will even out. If the going is good the engine will speed back up. If it's bad the engine will continue to lug down and eventually stall if you don't push the clutch.

[john2189]

Torque and RPMs make Horsepower.

Torque X RPM / 5252 = Horsepower

As the RPMs rise in an engine, torque rises, hits a peak, and then starts to fall off.

I think peak torque on a Cub engine is around 1500-1600 RPM if I'm not mistaken.

After 1600RPM the engine makes more Horsepower, but only by virtue of the RPMs rising faster than the torque is falling. Even that has a limit, and Horsepower starts to fall off at around 2000 or 2100 RPM, where the last Cub engines were running.

The later Cub-engined tractors were geared "slower" to take advantage of the increased HP at higher RPMs. They traveled the same speeds but only by virtue of the higher RPMs of the engine.

More RPMs without a gearing change is just more noise and a slightly longer run into the tall grass before the tractor begins to lug down. Normally the tractor will "seek its own level" where ground speed, mower speed, and available power will even out. If the going is good the engine will speed back up. If it's bad the engine will continue to lug down and eventually stall if you don't push the clutch.

Thanks, so what I should do is put a tach on the end of the pto shaft and see what the rpms are and then adjust the linkage or governor to the 1800 rpms right ?

[Glen]

Hi,
You didn't say if you are working on one of your 1949 Cubs, or the 1972 Cub. If it has a Battery Ignition Unit, you can hook on an electric test meter with a tachometer in it to the coil, and see the RPMs. If I remember, it says on the serial number plate on 1949 Cubs the max RPM is 1600. A 1972 Cub you could set at 1800 RPM.
Here is a page from the Cub parts book showing the governor. The max speed adjustment bolt is on the governor. It is number 13 in the pic. It has a lock nut too. Click on the pic makes it bigger.

http://www.farmallcub.info/manuals/cub_ ... 012-18.jpg

[outdoors4evr]

If you put in all of the engine upgrades that a 184 has (or a replacement engine from a 184), you can run a 60" mower deck at 1800 RPM's measured at the PTO. In a 184, the engine would be turning about 2200 RPM's to obtain this PTO RPM.
At this RPM, The tractor would be moving in 2nd gear at a speed of 3.8 MPH if it has the 8.3-24 tires.

If you do not have all the 184 upgrades, then you will probably just be putting unwanted stress on the engine components that would eventually end up with a component failure. Pretty easy to break a crankshaft, ask me how I know.

[Matt Kirsch]

1600 or 1800 either way with a standard Cub it's just going to make more noise sitting there wide open. Under a load you really won't notice the difference unless the governor isn't opening the throttle at the lower RPM for some reason.