Tune up question

[jamieg74]

I have just replaced basicaly all of the ignition components, rebuilt the govorner and the carb. I put everything back together and the cub runs but I want to make sure it runs as good as it can. What order should I use to tune things up? I am guessing timing and then the carb. Is there any adjustment for the govorner? If so where should I fit it in to the order of things?

Thanks

Jamie

[Hengy]

While you are tuning it up, make sure to adjust the valves so the gap is just right. Mine are set to 0.013 and it really helped the power of the tractor...

Mike in La Crosse, WI

[Cecil]

I usually do the timing first. Then using the low speed adjustment on the carb turn it until you get a smooth transition between low and hi speed. If it is set incorrectly there will be a hesitation from low to high. There are times when this will even cure surging that is caused by the governor hunting. If I do get a problem with governor hunting I always check the carb adjustment before I start adjusting the governor.

[JimT]

One other thing is to set your points before setting timing. Changing the points will change the timing.

[Gary Dotson]

As Mike mentioned, be sure to adjust the valves, so start with that first. Next, replace & adjust the points, replacing the condenser at the same time.

Replace spark plugs (and wires, cap, rotor, etc. if doing so) Be sure to confirm correct plug gap.

Check & adjust Ignition timing.

Start engine & warm up

Adjust carb. idle mixture.

If you have a tachometer, confirm no load RPM. (Varies with year, check manual) If adjustment is needed, adjust the stop screw on the lever on top of the governor.

[Hengy]

If you have a tachometer, confirm no load RPM. (Varies with year, check manual) If adjustment is needed, adjust the stop screw on the lever on top of the governor.

OK, this brings up a question. I have a 1949 Cub, so I am pretty sure that it is a 1600RPM engine. Will I kill the engine if it is adjusted to run at 1800RPM? What about 2000RPM like some of the later cubs?

What detriment will the extra 200 or 400 RPM have on a 1600RPM engine? What is the differences that allow the engine to run faster without killing it?

OK...that was several questions....

Mike in La Crosse, WI

[Eugene]

If you have a tachometer, confirm no load RPM. (Varies with year, check manual) If adjustment is needed, adjust the stop screw on the lever on top of the governor.

OK, this brings up a question. I have a 1949 Cub, so I am pretty sure that it is a 1600RPM engine. Will I kill the engine if it is adjusted to run at 1800RPM? What about 2000RPM like some of the later cubs?

What detriment will the extra 200 or 400 RPM have on a 1600RPM engine? What is the differences that allow the engine to run faster without killing it?Mike in La Crosse, WI

An opinion. Engine RPM, high idle and low idle. I have several tachs but set my tractor engines RPMs by ear and feel.

1600 RPMs is the maximum torque for the C-60 engine. 1800 and 2000 RPM give you a bit more horsepower. Will the additional 200 or 400 RPMs kill the engine - not on an engine in good mechanical condition.

Changing the length of the linkage between the carburator and govenor arm will (should) add a few RPMs. You could also change over the manifold and add the larger carburator. You could have the distributor reworked to increase the advance. But, it's a tractor not a race car.

[gitractorman]

Mike,
The later cubs with higher horsepower did have a couple of differences. One was the Zenith Carb, which has larger intakes, and therefore moves more gas and air. The other was domed pistons in the engine.

Can you increase the rpm on your engine. Yes, and it probably will not hurt anything, as long as you do not run it wide open all of the time. However, if you look up the power curve on the engine, the engine was designed to give the greatest torque at about 1600 rpm, and the htorque actually drops off after about 1800 rpm. So, increasing the rpm on your tractor will really not do anything positive towards power, since torque gives you power to operate/pull implements, other than implements and ground speed will be very slightly faster.



Bill

[Jim Becker]

Changing the length of the linkage between the carburator and govenor arm will (should) add a few RPMs.

This isn't a good idea. The main effect will be to potentially mess up the governor behavior or keep the engine from idling down properly.

This rod should be adjusted with the engine off. Push the control lever fully forward, hold the throttle wide open at the carb and adjust the length of the rod so the pin will just slide in without disturbing the position of any other parts. You are likely to find that there is enough wear in the various connections that there is some range of length adjustment that will allow the pin to be installed. I always adjust the rod as long as possible while still allowing the pin to go in.

[Trent M]

Jim- In GSS-1411, pg 2-18, it is recommended to do the gov-to-carb rod adjustment with the operator's control at half-speed. What would be the difference in pushing the operator's control fully forward?

[Trent M]

Jim- I think I may have figured it out. Did you mean to push the governor control rockshaft arm all the way back, as oposed to the operator's throttle control?

Yes its true, I'm a little slow, but I catch up eventually.

[Eugene]

Changing the length of the linkage between the carburator and govenor arm will (should) add a few RPMs.

This isn't a good idea. The main effect will be to potentially mess up the governor behavior or keep the engine from idling down properly.

This won't affect the govenor behavior/operation but it could limit the engine's ability to idle down somewhat. My Cub, and probably most Cubs, has enough slop/wear in the linkage, if adjusted to compensate, would add a few RPMs.

The topic was adding 200 to 400 engine RPMs. At approximately 1600 RPM, the butterfly valve/plate throttle valve in my Cub's carburator is not fully open. The ungovernored C60 engine is capable of considerably more than 2000 rpms. I had the govenor connecting rod drop out of the carburator - run away engine.

[Jim Becker]

Jim- In GSS-1411, pg 2-18, it is recommended to do the gov-to-carb rod adjustment with the operator's control at half-speed. What would be the difference in pushing the operator's control fully forward?

I did mean the operator's control. I think if everything is in perfect condition, pushing the lever anythere from about 1/3 to full will give the same result. It will put enough tension on the governor spring to rotate the rockshaft back. But again, with worn patrs . . .

[Gary Dotson]

I agree with Jim on gov. rod adjustment. There is only one way to correctly adjust the rod length, it's all about having the whole system in sync. While changing the length will somewhat affect maximum RPM, it will have an adverse effect on Gov. response. The stop screw on the lever was put there purposely, for adjusting no load RPM.

Mike, you can run your engine at 1800 or 2000 RPM if you would like, it's not likely to cause any problem at all. You'll likely run out of adjustment before reaching 2000, though.

My Cub has a power unit gov. on it, and will run much faster than 2000. It should have self destructed by now, but seems no worse for wear. I always knew a was kinda fast, but when we checked it with George's tach, we were both surprised - 3017 RPM!!!!! I seldom run full throttle!