Hi 38,
By and large, agreed... but one thing that is generally overlooked is the length (number of coils) of the spring.... To give a rather oversimplified example, a little imagination is required, so here goes....
Imagine a spring of infinite length, ie the little bit of stretch that the governor linkage gives it, causes little to no increase in tension over the governor arm travel.... The motor starts and speeds up, the rack being held open by the spring... as the weights give enough force to overcome the spring, they fly outwards, but the spring tension doesn't increase noticeably as there is little increase in its length ratio....ie it is still resisting the pull of the governor with pretty much the same force as it started with.... now we need to look inside the governor at the weights for a moment... they started held close to the camshaft, but are now some distance from it as they have overcome the spring tension... As their displacement from center increases, so does their "pull" on the spring...but the spring has the same amount of force on it as when it started, so the governor weights fly out a little more, and continue doing so, until they max out their travel and as such, have closed the rack (hopefully) fully.... The engine starts to wind down but the governor weights will continue to overcome the spring, until it is well below the revs you are aiming at... The cycle then starts again, ad infinitum....
But, if the spring is unreasonably short (few to no coils), the increasing tension in the spring overcomes the governor weights before they can fly out and throttle back on the rack, causing overspeed.... To alleviate this, one would think that by simply giving the system a bit of slack on the spring would solve it....Not so. if there is no "residual" or "start" tension to pull the rack to a reasonable semblance of fully open to get maximum power...
I found, for best performance on the few units I have played with over the last few decades, stick with the longest springs possible to get the beast to your required level of governing needed...
800 RPM weights were probably made a bit lighter to allow for the same governor springs to be used. Would you be so kind as to check your books to see if the governor springs were of similar nature across the range, just for interests' sake....
With a bit of playing about to verify the above info, I have, in the past, been able to successfully govern the beasts way lower than their intended rpm, granted, due to low rpm they are a tad "lazy" to take up load, but this I ascribe more to the fact that when turning slowly at around 250 to 350 rpm, load can be applied a damn side quicker than the inertia of the flywheels can sustain, hence a rapid sag and a slow recovery...but hey, lets not get too deep in here!!
About the Amish unit... that could work, but its a crap shoot, constant force on the governor arm, relying on forces changing due to a "geometry change" as the weights on the governor fly outwards around their hinge pin...Whichever way you look at it, the weights would have to only work above the centerline of their hinge pins to give a reasonable semblance of regulation ...
Still though, the the biggest problems that I have noted so far, are binding and secondarily wear or slop on the linkage.... with too much slop, the pump wont respond snappily, and likewise with binding...
To overcome the crappy fit and finish of the Indian CS's I have put very weak springs on the racks of the IP's, effectively getting round the sloppy fit that is sometimes "required" to prevent the binding... One of my units has it on the "Pull to open" side, the other has it on the "Pull to close" side, they work the same performance wise, but one will survive a little better should a linkage fail... Incidentally, both were 1000rpm units that I have governed down to 750 and 650rpm respectively.... They both hold frequency to within about 1 to 1.5hz (If I remember correctly)....
Enough of my bs...
Cheers
Ed