Governor tuning

Well, thanks to all of the advise so far. Got the carb rebuilt everything else is good so far. The governor tolerances all seem good, I want to tweak the governor to get better response. Where do I start?

These governors are simple proportional controllers: there isn't much to tweak. You can increase the gain and get slightly faster response at the price of increased overshoot (and perhaps oscillation if you overdo it). How you do that depends on the exact design of the governor in question.

What do you want to achieve? For most purposes you can do no better than making sure that the governor is working as designed.

Well one thing you would have to do is get youself a gram scale and reduce the weight off the throw weights on the governor. It will give you better response if that is what your after.
Charles

Shaving the weights will reduce the gain.

Worked for me, maybe mine is different.
Charles

How? The spring opens the throttle, the weights close it. Put in a new spring is about all that is needed.

> The spring opens the throttle, the weights close it.

The spring exerts force that tends to open the throttle, while the centrifugal force on the weights (transferred through the thrust bearing and the rocker arm) exerts force that tends to close it. When the two forces are equal the throttle doesn't move.

Shaving the weights will reduce the amount of additional force they exert on the spring for a given increase in speed. This will result in a smaller change in throttle position for a given change in speed: a reduction in gain.

> Put in a new spring is about all that is
> needed.

Yes, a weaker spring will increase the gain.

Of course, we don't actually know what the OP means by "response". If he just wants the engine to speed up faster when he pushes the speed control to maximum he should add an accelerator pump[1]. If that does not suffice he should disconnect the governor and connect the speed control linkage directly to the throttle.

If he wants faster response to a step change in load, there isn't a lot to be done. Increasing the gain will give slightly better step response at the price of increased overshoot but to go beyond that would require fancy electronics.

[1] The accelerator pump should be operated only by the speed control, of course. Putting it inside the loop might produce interesting results, but only on someone else's machine.

Hi:
Where could I purchase either a governor spring for my pierce governor or a pierce governor # GC6912FR288 338505R91. I have looked all the places I can think of. Thanks
james